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-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/AnimateSharedAsState.kt162
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/AnimateToScene.kt150
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/Element.kt449
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/Key.kt80
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/ObservableTransitionState.kt71
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/Scene.kt90
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SceneTransitionLayout.kt141
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SceneTransitionLayoutImpl.kt214
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SceneTransitionLayoutState.kt72
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SceneTransitions.kt176
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SwipeToScene.kt419
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/TransitionDsl.kt194
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/TransitionDslImpl.kt159
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/AnchoredSize.kt59
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/AnchoredTranslate.kt66
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/EdgeTranslate.kt74
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/Fade.kt41
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/PunchHole.kt91
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/ScaleSize.kt49
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/Transformation.kt138
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/Translate.kt49
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/modifiers/ConditionalModifiers.kt (renamed from packages/SystemUI/compose/features/src/com/android/systemui/compose/modifiers/ConditionalModifiers.kt)2
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/ui/util/ListUtils.kt55
-rw-r--r--packages/SystemUI/compose/core/src/com/android/compose/ui/util/MathHelpers.kt11
-rw-r--r--packages/SystemUI/compose/core/tests/Android.bp2
-rw-r--r--packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/ObservableTransitionStateTest.kt97
-rw-r--r--packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/SceneTransitionLayoutTest.kt323
-rw-r--r--packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/SwipeToSceneTest.kt241
-rw-r--r--packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/TestTransition.kt217
-rw-r--r--packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/TestValues.kt58
-rw-r--r--packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/AnchoredSizeTest.kt88
-rw-r--r--packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/AnchoredTranslateTest.kt86
-rw-r--r--packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/EdgeTranslateTest.kt153
-rw-r--r--packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/ScaleSizeTest.kt60
-rw-r--r--packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/TranslateTest.kt84
-rw-r--r--packages/SystemUI/compose/core/tests/src/com/android/compose/test/SizeAssertions.kt27
-rw-r--r--packages/SystemUI/compose/core/tests/src/com/android/compose/test/subjects/DpOffsetSubject.kt58
-rw-r--r--packages/SystemUI/compose/features/src/com/android/systemui/bouncer/ui/composable/PatternBouncer.kt2
-rw-r--r--packages/SystemUI/compose/features/src/com/android/systemui/bouncer/ui/composable/PinBouncer.kt3
39 files changed, 4505 insertions, 6 deletions
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/AnimateSharedAsState.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/AnimateSharedAsState.kt
new file mode 100644
index 000000000000..566967f920d3
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/AnimateSharedAsState.kt
@@ -0,0 +1,162 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.runtime.DisposableEffectResult
+import androidx.compose.runtime.DisposableEffectScope
+import androidx.compose.runtime.State
+import androidx.compose.runtime.derivedStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.lerp
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.lerp
+import com.android.compose.ui.util.lerp
+
+/**
+ * Animate a shared Int value.
+ *
+ * @see SceneScope.animateSharedValueAsState
+ */
+@Composable
+fun SceneScope.animateSharedIntAsState(
+ value: Int,
+ key: ValueKey,
+ element: ElementKey,
+ canOverflow: Boolean = true,
+): State<Int> {
+ return animateSharedValueAsState(value, key, element, ::lerp, canOverflow)
+}
+
+/**
+ * Animate a shared Float value.
+ *
+ * @see SceneScope.animateSharedValueAsState
+ */
+@Composable
+fun SceneScope.animateSharedFloatAsState(
+ value: Float,
+ key: ValueKey,
+ element: ElementKey,
+ canOverflow: Boolean = true,
+): State<Float> {
+ return animateSharedValueAsState(value, key, element, ::lerp, canOverflow)
+}
+
+/**
+ * Animate a shared Dp value.
+ *
+ * @see SceneScope.animateSharedValueAsState
+ */
+@Composable
+fun SceneScope.animateSharedDpAsState(
+ value: Dp,
+ key: ValueKey,
+ element: ElementKey,
+ canOverflow: Boolean = true,
+): State<Dp> {
+ return animateSharedValueAsState(value, key, element, ::lerp, canOverflow)
+}
+
+/**
+ * Animate a shared Color value.
+ *
+ * @see SceneScope.animateSharedValueAsState
+ */
+@Composable
+fun SceneScope.animateSharedColorAsState(
+ value: Color,
+ key: ValueKey,
+ element: ElementKey,
+): State<Color> {
+ return animateSharedValueAsState(value, key, element, ::lerp, canOverflow = false)
+}
+
+@Composable
+internal fun <T> animateSharedValueAsState(
+ layoutImpl: SceneTransitionLayoutImpl,
+ scene: Scene,
+ element: Element,
+ key: ValueKey,
+ value: T,
+ lerp: (T, T, Float) -> T,
+ canOverflow: Boolean,
+): State<T> {
+ val sharedValue = remember(key) { Element.SharedValue(key, value) }
+ if (value != sharedValue.value) {
+ sharedValue.value = value
+ }
+
+ DisposableEffect(element, scene, sharedValue) {
+ addSharedValueToElement(element, scene, sharedValue)
+ }
+
+ return remember(layoutImpl, element, sharedValue, lerp, canOverflow) {
+ derivedStateOf { computeValue(layoutImpl, element, sharedValue, lerp, canOverflow) }
+ }
+}
+
+private fun <T> DisposableEffectScope.addSharedValueToElement(
+ element: Element,
+ scene: Scene,
+ sharedValue: Element.SharedValue<T>,
+): DisposableEffectResult {
+ val sceneValues =
+ element.sceneValues[scene.key] ?: error("Element $element is not present in $scene")
+ val sharedValues = sceneValues.sharedValues
+
+ sharedValues[sharedValue.key] = sharedValue
+ return onDispose { sharedValues.remove(sharedValue.key) }
+}
+
+private fun <T> computeValue(
+ layoutImpl: SceneTransitionLayoutImpl,
+ element: Element,
+ sharedValue: Element.SharedValue<T>,
+ lerp: (T, T, Float) -> T,
+ canOverflow: Boolean,
+): T {
+ val state = layoutImpl.state.transitionState
+ if (
+ state !is TransitionState.Transition ||
+ state.fromScene == state.toScene ||
+ !layoutImpl.isTransitionReady(state)
+ ) {
+ return sharedValue.value
+ }
+
+ fun sceneValue(scene: SceneKey): Element.SharedValue<T>? {
+ val sceneValues = element.sceneValues[scene] ?: return null
+ val value = sceneValues.sharedValues[sharedValue.key] ?: return null
+ return value as Element.SharedValue<T>
+ }
+
+ val fromValue = sceneValue(state.fromScene)
+ val toValue = sceneValue(state.toScene)
+ return if (fromValue != null && toValue != null) {
+ val progress = if (canOverflow) state.progress else state.progress.coerceIn(0f, 1f)
+ lerp(fromValue.value, toValue.value, progress)
+ } else if (fromValue != null) {
+ fromValue.value
+ } else if (toValue != null) {
+ toValue.value
+ } else {
+ sharedValue.value
+ }
+}
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/AnimateToScene.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/AnimateToScene.kt
new file mode 100644
index 000000000000..753672820e28
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/AnimateToScene.kt
@@ -0,0 +1,150 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene
+
+import androidx.compose.animation.core.Animatable
+import androidx.compose.animation.core.AnimationVector1D
+import androidx.compose.animation.core.SpringSpec
+import kotlin.math.absoluteValue
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.launch
+
+/**
+ * Transition to [target] using a canned animation. This function will try to be smart and take over
+ * the currently running transition, if there is one.
+ */
+internal fun CoroutineScope.animateToScene(
+ layoutImpl: SceneTransitionLayoutImpl,
+ target: SceneKey,
+) {
+ val state = layoutImpl.state.transitionState
+ if (state.currentScene == target) {
+ // This can happen in 3 different situations, for which there isn't anything else to do:
+ // 1. There is no ongoing transition and [target] is already the current scene.
+ // 2. The user is swiping to [target] from another scene and released their pointer such
+ // that the gesture was committed and the transition is animating to [scene] already.
+ // 3. The user is swiping from [target] to another scene and either:
+ // a. didn't release their pointer yet.
+ // b. released their pointer such that the swipe gesture was cancelled and the
+ // transition is currently animating back to [target].
+ return
+ }
+
+ when (state) {
+ is TransitionState.Idle -> animate(layoutImpl, target)
+ is TransitionState.Transition -> {
+ if (state.toScene == state.fromScene) {
+ // Same as idle.
+ animate(layoutImpl, target)
+ return
+ }
+
+ // A transition is currently running: first check whether `transition.toScene` or
+ // `transition.fromScene` is the same as our target scene, in which case the transition
+ // can be accelerated or reversed to end up in the target state.
+
+ if (state.toScene == target) {
+ // The user is currently swiping to [target] but didn't release their pointer yet:
+ // animate the progress to `1`.
+
+ check(state.fromScene == state.currentScene)
+ val progress = state.progress
+ if ((1f - progress).absoluteValue < ProgressVisibilityThreshold) {
+ // The transition is already finished (progress ~= 1): no need to animate.
+ layoutImpl.state.transitionState = TransitionState.Idle(state.currentScene)
+ } else {
+ // The transition is in progress: start the canned animation at the same
+ // progress as it was in.
+ // TODO(b/290184746): Also take the current velocity into account.
+ animate(layoutImpl, target, startProgress = progress)
+ }
+
+ return
+ }
+
+ if (state.fromScene == target) {
+ // There is a transition from [target] to another scene: simply animate the same
+ // transition progress to `0`.
+
+ check(state.toScene == state.currentScene)
+ val progress = state.progress
+ if (progress.absoluteValue < ProgressVisibilityThreshold) {
+ // The transition is at progress ~= 0: no need to animate.
+ layoutImpl.state.transitionState = TransitionState.Idle(state.currentScene)
+ } else {
+ // TODO(b/290184746): Also take the current velocity into account.
+ animate(layoutImpl, target, startProgress = progress, reversed = true)
+ }
+
+ return
+ }
+
+ // Generic interruption; the current transition is neither from or to [target].
+ // TODO(b/290930950): Better handle interruptions here.
+ animate(layoutImpl, target)
+ }
+ }
+}
+
+private fun CoroutineScope.animate(
+ layoutImpl: SceneTransitionLayoutImpl,
+ target: SceneKey,
+ startProgress: Float = 0f,
+ reversed: Boolean = false,
+) {
+ val fromScene = layoutImpl.state.transitionState.currentScene
+
+ val animationSpec = layoutImpl.transitions.transitionSpec(fromScene, target).spec
+ val visibilityThreshold =
+ (animationSpec as? SpringSpec)?.visibilityThreshold ?: ProgressVisibilityThreshold
+ val animatable = Animatable(startProgress, visibilityThreshold = visibilityThreshold)
+
+ val targetProgress = if (reversed) 0f else 1f
+ val transition =
+ if (reversed) {
+ OneOffTransition(target, fromScene, currentScene = target, animatable)
+ } else {
+ OneOffTransition(fromScene, target, currentScene = target, animatable)
+ }
+
+ // Change the current layout state to use this new transition.
+ layoutImpl.state.transitionState = transition
+
+ // Animate the progress to its target value.
+ launch {
+ animatable.animateTo(targetProgress, animationSpec)
+
+ // Unless some other external state change happened, the state should now be idle.
+ if (layoutImpl.state.transitionState == transition) {
+ layoutImpl.state.transitionState = TransitionState.Idle(target)
+ }
+ }
+}
+
+private class OneOffTransition(
+ override val fromScene: SceneKey,
+ override val toScene: SceneKey,
+ override val currentScene: SceneKey,
+ private val animatable: Animatable<Float, AnimationVector1D>,
+) : TransitionState.Transition {
+ override val progress: Float
+ get() = animatable.value
+}
+
+// TODO(b/290184746): Compute a good default visibility threshold that depends on the layout size
+// and screen density.
+private const val ProgressVisibilityThreshold = 1e-3f
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/Element.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/Element.kt
new file mode 100644
index 000000000000..0cc259ab7015
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/Element.kt
@@ -0,0 +1,449 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.runtime.SideEffect
+import androidx.compose.runtime.derivedStateOf
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.runtime.snapshots.Snapshot
+import androidx.compose.runtime.snapshots.SnapshotStateMap
+import androidx.compose.ui.ExperimentalComposeUiApi
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.drawWithContent
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.geometry.isSpecified
+import androidx.compose.ui.geometry.lerp
+import androidx.compose.ui.graphics.graphicsLayer
+import androidx.compose.ui.layout.IntermediateMeasureScope
+import androidx.compose.ui.layout.Measurable
+import androidx.compose.ui.layout.Placeable
+import androidx.compose.ui.layout.intermediateLayout
+import androidx.compose.ui.platform.testTag
+import androidx.compose.ui.unit.Constraints
+import androidx.compose.ui.unit.IntSize
+import androidx.compose.ui.unit.round
+import com.android.compose.animation.scene.transformation.PropertyTransformation
+import com.android.compose.modifiers.thenIf
+import com.android.compose.ui.util.lerp
+
+/** An element on screen, that can be composed in one or more scenes. */
+internal class Element(val key: ElementKey) {
+ /**
+ * The last offset assigned to this element, relative to the SceneTransitionLayout containing
+ * it.
+ */
+ var lastOffset = Offset.Unspecified
+
+ /** The last size assigned to this element. */
+ var lastSize = SizeUnspecified
+
+ /** The last alpha assigned to this element. */
+ var lastAlpha = 1f
+
+ /** The mapping between a scene and the values/state this element has in that scene, if any. */
+ val sceneValues = SnapshotStateMap<SceneKey, SceneValues>()
+
+ override fun toString(): String {
+ return "Element(key=$key)"
+ }
+
+ /** The target values of this element in a given scene. */
+ class SceneValues {
+ var size by mutableStateOf(SizeUnspecified)
+ var offset by mutableStateOf(Offset.Unspecified)
+ val sharedValues = SnapshotStateMap<ValueKey, SharedValue<*>>()
+ }
+
+ /** A shared value of this element. */
+ class SharedValue<T>(val key: ValueKey, initialValue: T) {
+ var value by mutableStateOf(initialValue)
+ }
+
+ companion object {
+ val SizeUnspecified = IntSize(Int.MAX_VALUE, Int.MAX_VALUE)
+ }
+}
+
+/** The implementation of [SceneScope.element]. */
+@Composable
+@OptIn(ExperimentalComposeUiApi::class)
+internal fun Modifier.element(
+ layoutImpl: SceneTransitionLayoutImpl,
+ scene: Scene,
+ key: ElementKey,
+): Modifier {
+ val sceneValues = remember(scene, key) { Element.SceneValues() }
+ val element =
+ // Get the element associated to [key] if it was already composed in another scene,
+ // otherwise create it and add it to our Map<ElementKey, Element>. This is done inside a
+ // withoutReadObservation() because there is no need to recompose when that map is mutated.
+ Snapshot.withoutReadObservation {
+ val element =
+ layoutImpl.elements[key] ?: Element(key).also { layoutImpl.elements[key] = it }
+ val previousValues = element.sceneValues[scene.key]
+ if (previousValues == null) {
+ element.sceneValues[scene.key] = sceneValues
+ } else if (previousValues != sceneValues) {
+ error("$key was composed multiple times in $scene")
+ }
+
+ element
+ }
+
+ DisposableEffect(scene, sceneValues, element) {
+ onDispose {
+ element.sceneValues.remove(scene.key)
+
+ // This was the last scene this element was in, so remove it from the map.
+ if (element.sceneValues.isEmpty()) {
+ layoutImpl.elements.remove(element.key)
+ }
+ }
+ }
+
+ val alpha =
+ remember(layoutImpl, element, scene) {
+ derivedStateOf { elementAlpha(layoutImpl, element, scene) }
+ }
+ val isOpaque by remember(alpha) { derivedStateOf { alpha.value == 1f } }
+ SideEffect {
+ if (isOpaque && element.lastAlpha != 1f) {
+ element.lastAlpha = 1f
+ }
+ }
+
+ return drawWithContent {
+ if (shouldDrawElement(layoutImpl, scene, element)) {
+ drawContent()
+ }
+ }
+ .modifierTransformations(layoutImpl, scene, element, sceneValues)
+ .intermediateLayout { measurable, constraints ->
+ val placeable =
+ measure(layoutImpl, scene, element, sceneValues, measurable, constraints)
+ layout(placeable.width, placeable.height) {
+ place(layoutImpl, scene, element, sceneValues, placeable, placementScope = this)
+ }
+ }
+ .thenIf(!isOpaque) {
+ Modifier.graphicsLayer {
+ val alpha = alpha.value
+ this.alpha = alpha
+ element.lastAlpha = alpha
+ }
+ }
+ .testTag(key.name)
+}
+
+private fun shouldDrawElement(
+ layoutImpl: SceneTransitionLayoutImpl,
+ scene: Scene,
+ element: Element,
+): Boolean {
+ val state = layoutImpl.state.transitionState
+
+ // Always draw the element if there is no ongoing transition or if the element is not shared.
+ if (
+ state !is TransitionState.Transition ||
+ state.fromScene == state.toScene ||
+ !layoutImpl.isTransitionReady(state) ||
+ state.fromScene !in element.sceneValues ||
+ state.toScene !in element.sceneValues
+ ) {
+ return true
+ }
+
+ val otherScene =
+ layoutImpl.scenes.getValue(
+ if (scene.key == state.fromScene) {
+ state.toScene
+ } else {
+ state.fromScene
+ }
+ )
+
+ // When the element is shared, draw the one in the highest scene unless it is a background, i.e.
+ // it is usually drawn below everything else.
+ val isHighestScene = scene.zIndex > otherScene.zIndex
+ return if (element.key.isBackground) {
+ !isHighestScene
+ } else {
+ isHighestScene
+ }
+}
+
+/**
+ * Chain the [com.android.compose.animation.scene.transformation.ModifierTransformation] applied
+ * throughout the current transition, if any.
+ */
+private fun Modifier.modifierTransformations(
+ layoutImpl: SceneTransitionLayoutImpl,
+ scene: Scene,
+ element: Element,
+ sceneValues: Element.SceneValues,
+): Modifier {
+ when (val state = layoutImpl.state.transitionState) {
+ is TransitionState.Idle -> return this
+ is TransitionState.Transition -> {
+ val fromScene = state.fromScene
+ val toScene = state.toScene
+ if (fromScene == toScene) {
+ // Same as idle.
+ return this
+ }
+
+ return layoutImpl.transitions
+ .transitionSpec(fromScene, state.toScene)
+ .transformations(element.key)
+ .modifier
+ .fold(this) { modifier, transformation ->
+ with(transformation) {
+ modifier.transform(layoutImpl, scene, element, sceneValues)
+ }
+ }
+ }
+ }
+}
+
+private fun elementAlpha(
+ layoutImpl: SceneTransitionLayoutImpl,
+ element: Element,
+ scene: Scene
+): Float {
+ return computeValue(
+ layoutImpl,
+ scene,
+ element,
+ sceneValue = { 1f },
+ transformation = { it.alpha },
+ idleValue = 1f,
+ currentValue = { 1f },
+ lastValue = { element.lastAlpha },
+ ::lerp,
+ )
+ .coerceIn(0f, 1f)
+}
+
+@OptIn(ExperimentalComposeUiApi::class)
+private fun IntermediateMeasureScope.measure(
+ layoutImpl: SceneTransitionLayoutImpl,
+ scene: Scene,
+ element: Element,
+ sceneValues: Element.SceneValues,
+ measurable: Measurable,
+ constraints: Constraints,
+): Placeable {
+ // Update the size this element has in this scene when idle.
+ val targetSizeInScene = lookaheadSize
+ if (targetSizeInScene != sceneValues.size) {
+ // TODO(b/290930950): Better handle when this changes to avoid instant size jumps.
+ sceneValues.size = targetSizeInScene
+ }
+
+ // Some lambdas called (max once) by computeValue() will need to measure [measurable], in which
+ // case we store the resulting placeable here to make sure the element is not measured more than
+ // once.
+ var maybePlaceable: Placeable? = null
+
+ fun Placeable.size() = IntSize(width, height)
+
+ val targetSize =
+ computeValue(
+ layoutImpl,
+ scene,
+ element,
+ sceneValue = { it.size },
+ transformation = { it.size },
+ idleValue = lookaheadSize,
+ currentValue = { measurable.measure(constraints).also { maybePlaceable = it }.size() },
+ lastValue = {
+ val lastSize = element.lastSize
+ if (lastSize != Element.SizeUnspecified) {
+ lastSize
+ } else {
+ measurable.measure(constraints).also { maybePlaceable = it }.size()
+ }
+ },
+ ::lerp,
+ )
+
+ val placeable =
+ maybePlaceable
+ ?: measurable.measure(
+ Constraints.fixed(
+ targetSize.width.coerceAtLeast(0),
+ targetSize.height.coerceAtLeast(0),
+ )
+ )
+
+ element.lastSize = placeable.size()
+ return placeable
+}
+
+@OptIn(ExperimentalComposeUiApi::class)
+private fun IntermediateMeasureScope.place(
+ layoutImpl: SceneTransitionLayoutImpl,
+ scene: Scene,
+ element: Element,
+ sceneValues: Element.SceneValues,
+ placeable: Placeable,
+ placementScope: Placeable.PlacementScope,
+) {
+ with(placementScope) {
+ // Update the offset (relative to the SceneTransitionLayout) this element has in this scene
+ // when idle.
+ val coords = coordinates!!
+ val targetOffsetInScene = lookaheadScopeCoordinates.localLookaheadPositionOf(coords)
+ if (targetOffsetInScene != sceneValues.offset) {
+ // TODO(b/290930950): Better handle when this changes to avoid instant offset jumps.
+ sceneValues.offset = targetOffsetInScene
+ }
+
+ val currentOffset = lookaheadScopeCoordinates.localPositionOf(coords, Offset.Zero)
+ val targetOffset =
+ computeValue(
+ layoutImpl,
+ scene,
+ element,
+ sceneValue = { it.offset },
+ transformation = { it.offset },
+ idleValue = targetOffsetInScene,
+ currentValue = { currentOffset },
+ lastValue = {
+ val lastValue = element.lastOffset
+ if (lastValue.isSpecified) {
+ lastValue
+ } else {
+ currentOffset
+ }
+ },
+ ::lerp,
+ )
+
+ element.lastOffset = targetOffset
+ placeable.place((targetOffset - currentOffset).round())
+ }
+}
+
+/**
+ * Return the value that should be used depending on the current layout state and transition.
+ *
+ * Important: This function must remain inline because of all the lambda parameters. These lambdas
+ * are necessary because getting some of them might require some computation, like measuring a
+ * Measurable.
+ *
+ * @param layoutImpl the [SceneTransitionLayoutImpl] associated to [element].
+ * @param scene the scene containing [element].
+ * @param element the element being animated.
+ * @param sceneValue the value being animated.
+ * @param transformation the transformation associated to the value being animated.
+ * @param idleValue the value when idle, i.e. when there is no transition happening.
+ * @param currentValue the value that would be used if it is not transformed. Note that this is
+ * different than [idleValue] even if the value is not transformed directly because it could be
+ * impacted by the transformations on other elements, like a parent that is being translated or
+ * resized.
+ * @param lastValue the last value that was used. This should be equal to [currentValue] if this is
+ * the first time the value is set.
+ * @param lerp the linear interpolation function used to interpolate between two values of this
+ * value type.
+ */
+private inline fun <T> computeValue(
+ layoutImpl: SceneTransitionLayoutImpl,
+ scene: Scene,
+ element: Element,
+ sceneValue: (Element.SceneValues) -> T,
+ transformation: (ElementTransformations) -> PropertyTransformation<T>?,
+ idleValue: T,
+ currentValue: () -> T,
+ lastValue: () -> T,
+ lerp: (T, T, Float) -> T,
+): T {
+ val state = layoutImpl.state.transitionState
+
+ // There is no ongoing transition.
+ if (state !is TransitionState.Transition || state.fromScene == state.toScene) {
+ return idleValue
+ }
+
+ // A transition was started but it's not ready yet (not all elements have been composed/laid
+ // out yet). Use the last value that was set, to make sure elements don't unexpectedly jump.
+ if (!layoutImpl.isTransitionReady(state)) {
+ return lastValue()
+ }
+
+ val fromScene = state.fromScene
+ val toScene = state.toScene
+ val fromValues = element.sceneValues[fromScene]
+ val toValues = element.sceneValues[toScene]
+
+ if (fromValues == null && toValues == null) {
+ error("This should not happen, element $element is neither in $fromScene or $toScene")
+ }
+
+ // TODO(b/291053278): Handle overscroll correctly. We should probably coerce between [0f, 1f]
+ // here and consume overflows at drawing time, somehow reusing Compose OverflowEffect or some
+ // similar mechanism.
+ val transitionProgress = state.progress
+
+ // The element is shared: interpolate between the value in fromScene and the value in toScene.
+ // TODO(b/290184746): Support non linear shared paths as well as a way to make sure that shared
+ // elements follow the finger direction.
+ if (fromValues != null && toValues != null) {
+ return lerp(
+ sceneValue(fromValues),
+ sceneValue(toValues),
+ transitionProgress,
+ )
+ }
+
+ val transformation =
+ transformation(
+ layoutImpl.transitions.transitionSpec(fromScene, toScene).transformations(element.key)
+ )
+ // If there is no transformation explicitly associated to this element value, let's use
+ // the value given by the system (like the current position and size given by the layout
+ // pass).
+ ?: return currentValue()
+
+ // Get the transformed value, i.e. the target value at the beginning (for entering elements) or
+ // end (for leaving elements) of the transition.
+ val targetValue =
+ transformation.transform(
+ layoutImpl,
+ scene,
+ element,
+ fromValues ?: toValues!!,
+ state,
+ idleValue,
+ )
+
+ // TODO(b/290184746): Make sure that we don't overflow transformations associated to a range.
+ val rangeProgress = transformation.range?.progress(transitionProgress) ?: transitionProgress
+
+ // Interpolate between the value at rest and the value before entering/after leaving.
+ val isEntering = fromValues == null
+ return if (isEntering) {
+ lerp(targetValue, idleValue, rangeProgress)
+ } else {
+ lerp(idleValue, targetValue, rangeProgress)
+ }
+}
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/Key.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/Key.kt
new file mode 100644
index 000000000000..c3f44f8b1069
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/Key.kt
@@ -0,0 +1,80 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene
+
+/**
+ * A base class to create unique keys, associated to an [identity] that is used to check the
+ * equality of two key instances.
+ */
+sealed class Key(val name: String, val identity: Any) {
+ override fun equals(other: Any?): Boolean {
+ if (this === other) return true
+ if (this.javaClass != other?.javaClass) return false
+ return identity == (other as? Key)?.identity
+ }
+
+ override fun hashCode(): Int {
+ return identity.hashCode()
+ }
+
+ override fun toString(): String {
+ return "Key(name=$name)"
+ }
+}
+
+/** Key for a scene. */
+class SceneKey(name: String, identity: Any = Object()) : Key(name, identity) {
+ override fun toString(): String {
+ return "SceneKey(name=$name)"
+ }
+}
+
+/** Key for an element. */
+class ElementKey(
+ name: String,
+ identity: Any = Object(),
+
+ /**
+ * Whether this element is a background and usually drawn below other elements. This should be
+ * set to true to make sure that shared backgrounds are drawn below elements of other scenes.
+ */
+ val isBackground: Boolean = false,
+) : Key(name, identity), ElementMatcher {
+ override fun matches(key: ElementKey): Boolean {
+ return key == this
+ }
+
+ override fun toString(): String {
+ return "ElementKey(name=$name)"
+ }
+
+ companion object {
+ /** Matches any element whose [key identity][ElementKey.identity] matches [predicate]. */
+ fun withIdentity(predicate: (Any) -> Boolean): ElementMatcher {
+ return object : ElementMatcher {
+ override fun matches(key: ElementKey): Boolean = predicate(key.identity)
+ }
+ }
+ }
+}
+
+/** Key for a shared value of an element. */
+class ValueKey(name: String, identity: Any = Object()) : Key(name, identity) {
+ override fun toString(): String {
+ return "ValueKey(name=$name)"
+ }
+}
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/ObservableTransitionState.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/ObservableTransitionState.kt
new file mode 100644
index 000000000000..a625250d1e51
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/ObservableTransitionState.kt
@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene
+
+import androidx.compose.runtime.snapshotFlow
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.distinctUntilChanged
+
+/**
+ * A scene transition state.
+ *
+ * This models the same thing as [TransitionState], with the following distinctions:
+ * 1. [TransitionState] values are backed by the Snapshot system (Compose State objects) and can be
+ * used by callers tracking State reads, for instance in Compose code during the composition,
+ * layout or Compose drawing phases.
+ * 2. [ObservableTransitionState] values are backed by Kotlin [Flow]s and can be collected by
+ * non-Compose code to observe value changes.
+ * 3. [ObservableTransitionState.Transition.fromScene] and
+ * [ObservableTransitionState.Transition.toScene] will never be equal, while
+ * [TransitionState.Transition.fromScene] and [TransitionState.Transition.toScene] can be equal.
+ */
+sealed class ObservableTransitionState {
+ /** No transition/animation is currently running. */
+ data class Idle(val scene: SceneKey) : ObservableTransitionState()
+
+ /** There is a transition animating between two scenes. */
+ data class Transition(
+ val fromScene: SceneKey,
+ val toScene: SceneKey,
+ val progress: Flow<Float>,
+ ) : ObservableTransitionState()
+}
+
+/**
+ * The current [ObservableTransitionState]. This models the same thing as
+ * [SceneTransitionLayoutState.transitionState], except that it is backed by Flows and can be used
+ * by non-Compose code to observe state changes.
+ */
+fun SceneTransitionLayoutState.observableTransitionState(): Flow<ObservableTransitionState> {
+ return snapshotFlow {
+ when (val state = transitionState) {
+ is TransitionState.Idle -> ObservableTransitionState.Idle(state.currentScene)
+ is TransitionState.Transition -> {
+ if (state.fromScene == state.toScene) {
+ ObservableTransitionState.Idle(state.currentScene)
+ } else {
+ ObservableTransitionState.Transition(
+ fromScene = state.fromScene,
+ toScene = state.toScene,
+ progress = snapshotFlow { state.progress },
+ )
+ }
+ }
+ }
+ }
+ .distinctUntilChanged()
+}
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/Scene.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/Scene.kt
new file mode 100644
index 000000000000..b44c8efc7ee2
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/Scene.kt
@@ -0,0 +1,90 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene
+
+import androidx.compose.foundation.layout.Box
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.State
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableFloatStateOf
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.layout.onPlaced
+import androidx.compose.ui.unit.IntSize
+import androidx.compose.ui.zIndex
+
+/** A scene in a [SceneTransitionLayout]. */
+internal class Scene(
+ val key: SceneKey,
+ layoutImpl: SceneTransitionLayoutImpl,
+ content: @Composable SceneScope.() -> Unit,
+ actions: Map<UserAction, SceneKey>,
+ zIndex: Float,
+) {
+ private val scope = SceneScopeImpl(layoutImpl, this)
+
+ var content by mutableStateOf(content)
+ var userActions by mutableStateOf(actions)
+ var zIndex by mutableFloatStateOf(zIndex)
+ var size by mutableStateOf(IntSize.Zero)
+
+ @Composable
+ fun Content(modifier: Modifier = Modifier) {
+ Box(modifier.zIndex(zIndex).onPlaced { size = it.size }) { scope.content() }
+ }
+
+ override fun toString(): String {
+ return "Scene(key=$key)"
+ }
+}
+
+private class SceneScopeImpl(
+ private val layoutImpl: SceneTransitionLayoutImpl,
+ private val scene: Scene,
+) : SceneScope {
+ @Composable
+ override fun Modifier.element(key: ElementKey): Modifier {
+ return element(layoutImpl, scene, key)
+ }
+
+ @Composable
+ override fun <T> animateSharedValueAsState(
+ value: T,
+ key: ValueKey,
+ element: ElementKey,
+ lerp: (T, T, Float) -> T,
+ canOverflow: Boolean
+ ): State<T> {
+ val element =
+ layoutImpl.elements[element]
+ ?: error(
+ "Element $element is not composed. Make sure to call animateSharedXAsState " +
+ "*after* Modifier.element(key)."
+ )
+
+ return animateSharedValueAsState(
+ layoutImpl,
+ scene,
+ element,
+ key,
+ value,
+ lerp,
+ canOverflow,
+ )
+ }
+}
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SceneTransitionLayout.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SceneTransitionLayout.kt
new file mode 100644
index 000000000000..39173d98538f
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SceneTransitionLayout.kt
@@ -0,0 +1,141 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.State
+import androidx.compose.runtime.remember
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalDensity
+
+/**
+ * [SceneTransitionLayout] is a container that automatically animates its content whenever
+ * [currentScene] changes, using the transitions defined in [transitions].
+ *
+ * Note: You should use [androidx.compose.animation.AnimatedContent] instead of
+ * [SceneTransitionLayout] if it fits your need. Use [SceneTransitionLayout] over AnimatedContent if
+ * you need support for swipe gestures, shared elements or transitions defined declaratively outside
+ * UI code.
+ *
+ * @param currentScene the current scene
+ * @param onChangeScene a mutator that should set [currentScene] to the given scene when called.
+ * This is called when the user commits a transition to a new scene because of a [UserAction], for
+ * instance by triggering back navigation or by swiping to a new scene.
+ * @param transitions the definition of the transitions used to animate a change of scene.
+ * @param state the observable state of this layout.
+ * @param scenes the configuration of the different scenes of this layout.
+ */
+@Composable
+fun SceneTransitionLayout(
+ currentScene: SceneKey,
+ onChangeScene: (SceneKey) -> Unit,
+ transitions: SceneTransitions,
+ modifier: Modifier = Modifier,
+ state: SceneTransitionLayoutState = remember { SceneTransitionLayoutState(currentScene) },
+ scenes: SceneTransitionLayoutScope.() -> Unit,
+) {
+ val density = LocalDensity.current
+ val layoutImpl = remember {
+ SceneTransitionLayoutImpl(
+ onChangeScene,
+ scenes,
+ transitions,
+ state,
+ density,
+ )
+ }
+
+ layoutImpl.onChangeScene = onChangeScene
+ layoutImpl.transitions = transitions
+ layoutImpl.density = density
+ layoutImpl.setScenes(scenes)
+ layoutImpl.setCurrentScene(currentScene)
+
+ layoutImpl.Content(modifier)
+}
+
+interface SceneTransitionLayoutScope {
+ /**
+ * Add a scene to this layout, identified by [key].
+ *
+ * You can configure [userActions] so that swiping on this layout or navigating back will
+ * transition to a different scene.
+ *
+ * Important: scene order along the z-axis follows call order. Calling scene(A) followed by
+ * scene(B) will mean that scene B renders after/above scene A.
+ */
+ fun scene(
+ key: SceneKey,
+ userActions: Map<UserAction, SceneKey> = emptyMap(),
+ content: @Composable SceneScope.() -> Unit,
+ )
+}
+
+interface SceneScope {
+ /**
+ * Tag an element identified by [key].
+ *
+ * Tagging an element will allow you to reference that element when defining transitions, so
+ * that the element can be transformed and animated when the scene transitions in or out.
+ *
+ * Additionally, this [key] will be used to detect elements that are shared between scenes to
+ * automatically interpolate their size, offset and [shared values][animateSharedValueAsState].
+ *
+ * TODO(b/291566282): Migrate this to the new Modifier Node API and remove the @Composable
+ * constraint.
+ */
+ @Composable fun Modifier.element(key: ElementKey): Modifier
+
+ /**
+ * Animate some value of a shared element.
+ *
+ * @param value the value of this shared value in the current scene.
+ * @param key the key of this shared value.
+ * @param element the element associated with this value.
+ * @param lerp the *linear* interpolation function that should be used to interpolate between
+ * two different values. Note that it has to be linear because the [fraction] passed to this
+ * interpolator is already interpolated.
+ * @param canOverflow whether this value can overflow past the values it is interpolated
+ * between, for instance because the transition is animated using a bouncy spring.
+ * @see animateSharedIntAsState
+ * @see animateSharedFloatAsState
+ * @see animateSharedDpAsState
+ * @see animateSharedColorAsState
+ */
+ @Composable
+ fun <T> animateSharedValueAsState(
+ value: T,
+ key: ValueKey,
+ element: ElementKey,
+ lerp: (start: T, stop: T, fraction: Float) -> T,
+ canOverflow: Boolean,
+ ): State<T>
+}
+
+/** An action performed by the user. */
+sealed interface UserAction
+
+/** The user navigated back, either using a gesture or by triggering a KEYCODE_BACK event. */
+object Back : UserAction
+
+/** The user swiped on the container. */
+enum class Swipe : UserAction {
+ Up,
+ Down,
+ Left,
+ Right,
+}
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SceneTransitionLayoutImpl.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SceneTransitionLayoutImpl.kt
new file mode 100644
index 000000000000..350b9c2550c8
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SceneTransitionLayoutImpl.kt
@@ -0,0 +1,214 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene
+
+import androidx.activity.compose.BackHandler
+import androidx.compose.foundation.gestures.Orientation
+import androidx.compose.foundation.layout.Box
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.SideEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.key
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.runtime.snapshots.SnapshotStateMap
+import androidx.compose.ui.ExperimentalComposeUiApi
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.drawWithContent
+import androidx.compose.ui.layout.LookaheadScope
+import androidx.compose.ui.layout.onSizeChanged
+import androidx.compose.ui.unit.Density
+import androidx.compose.ui.unit.IntSize
+import com.android.compose.ui.util.fastForEach
+import kotlinx.coroutines.channels.Channel
+
+internal class SceneTransitionLayoutImpl(
+ onChangeScene: (SceneKey) -> Unit,
+ builder: SceneTransitionLayoutScope.() -> Unit,
+ transitions: SceneTransitions,
+ internal val state: SceneTransitionLayoutState,
+ density: Density,
+) {
+ internal val scenes = SnapshotStateMap<SceneKey, Scene>()
+ internal val elements = SnapshotStateMap<ElementKey, Element>()
+
+ /** The scenes that are "ready", i.e. they were composed and fully laid-out at least once. */
+ private val readyScenes = SnapshotStateMap<SceneKey, Boolean>()
+
+ internal var onChangeScene by mutableStateOf(onChangeScene)
+ internal var transitions by mutableStateOf(transitions)
+ internal var density: Density by mutableStateOf(density)
+
+ /**
+ * The size of this layout. Note that this could be [IntSize.Zero] if this layour does not have
+ * any scene configured or right before the first measure pass of the layout.
+ */
+ internal var size by mutableStateOf(IntSize.Zero)
+
+ init {
+ setScenes(builder)
+ }
+
+ internal fun scene(key: SceneKey): Scene {
+ return scenes[key] ?: error("Scene $key is not configured")
+ }
+
+ internal fun setScenes(builder: SceneTransitionLayoutScope.() -> Unit) {
+ // Keep a reference of the current scenes. After processing [builder], the scenes that were
+ // not configured will be removed.
+ val scenesToRemove = scenes.keys.toMutableSet()
+
+ // The incrementing zIndex of each scene.
+ var zIndex = 0f
+
+ object : SceneTransitionLayoutScope {
+ override fun scene(
+ key: SceneKey,
+ userActions: Map<UserAction, SceneKey>,
+ content: @Composable SceneScope.() -> Unit,
+ ) {
+ scenesToRemove.remove(key)
+
+ val scene = scenes[key]
+ if (scene != null) {
+ // Update an existing scene.
+ scene.content = content
+ scene.userActions = userActions
+ scene.zIndex = zIndex
+ } else {
+ // New scene.
+ scenes[key] =
+ Scene(
+ key,
+ this@SceneTransitionLayoutImpl,
+ content,
+ userActions,
+ zIndex,
+ )
+ }
+
+ zIndex++
+ }
+ }
+ .builder()
+
+ scenesToRemove.forEach { scenes.remove(it) }
+ }
+
+ @Composable
+ internal fun setCurrentScene(key: SceneKey) {
+ val channel = remember { Channel<SceneKey>(Channel.CONFLATED) }
+ SideEffect { channel.trySend(key) }
+ LaunchedEffect(channel) {
+ for (newKey in channel) {
+ // Inspired by AnimateAsState.kt: let's poll the last value to avoid being one frame
+ // late.
+ val newKey = channel.tryReceive().getOrNull() ?: newKey
+ animateToScene(this@SceneTransitionLayoutImpl, newKey)
+ }
+ }
+ }
+
+ @Composable
+ @OptIn(ExperimentalComposeUiApi::class)
+ internal fun Content(modifier: Modifier) {
+ Box(
+ modifier
+ // Handle horizontal and vertical swipes on this layout.
+ // Note: order here is important and will give a slight priority to the vertical
+ // swipes.
+ .swipeToScene(layoutImpl = this, Orientation.Horizontal)
+ .swipeToScene(layoutImpl = this, Orientation.Vertical)
+ .onSizeChanged { size = it }
+ ) {
+ LookaheadScope {
+ val scenesToCompose =
+ when (val state = state.transitionState) {
+ is TransitionState.Idle -> listOf(scene(state.currentScene))
+ is TransitionState.Transition -> {
+ if (state.toScene != state.fromScene) {
+ listOf(scene(state.toScene), scene(state.fromScene))
+ } else {
+ listOf(scene(state.fromScene))
+ }
+ }
+ }
+
+ // Handle back events.
+ // TODO(b/290184746): Make sure that this works with SystemUI once we use
+ // SceneTransitionLayout in Flexiglass.
+ scene(state.transitionState.currentScene).userActions[Back]?.let { backScene ->
+ BackHandler { onChangeScene(backScene) }
+ }
+
+ Box(
+ Modifier.drawWithContent {
+ drawContent()
+
+ // At this point, all scenes in scenesToCompose are fully laid out so they
+ // are marked as ready. This is necessary because the animation code needs
+ // to know the position and size of the elements in each scenes they are in,
+ // so [readyScenes] will be used to decide whether the transition is ready
+ // (see isTransitionReady() below).
+ //
+ // We can't do that in a DisposableEffect or SideEffect because those are
+ // run between composition and layout. LaunchedEffect could work and might
+ // be better, but it looks like launched effects run a frame later than this
+ // code so doing this here seems better for performance.
+ scenesToCompose.fastForEach { readyScenes[it.key] = true }
+ }
+ ) {
+ scenesToCompose.fastForEach { scene ->
+ val key = scene.key
+ key(key) {
+ DisposableEffect(key) { onDispose { readyScenes.remove(key) } }
+
+ scene.Content(
+ Modifier.drawWithContent {
+ when (val state = state.transitionState) {
+ is TransitionState.Idle -> drawContent()
+ is TransitionState.Transition -> {
+ // Don't draw scenes that are not ready yet.
+ if (
+ readyScenes.containsKey(key) ||
+ state.fromScene == state.toScene
+ ) {
+ drawContent()
+ }
+ }
+ }
+ }
+ )
+ }
+ }
+ }
+ }
+ }
+ }
+
+ /**
+ * Return whether [transition] is ready, i.e. the elements of both scenes of the transition were
+ * laid out at least once.
+ */
+ internal fun isTransitionReady(transition: TransitionState.Transition): Boolean {
+ return readyScenes.containsKey(transition.fromScene) &&
+ readyScenes.containsKey(transition.toScene)
+ }
+}
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SceneTransitionLayoutState.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SceneTransitionLayoutState.kt
new file mode 100644
index 000000000000..47e3d5add27b
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SceneTransitionLayoutState.kt
@@ -0,0 +1,72 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene
+
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+
+/** The state of a [SceneTransitionLayout]. */
+class SceneTransitionLayoutState(initialScene: SceneKey) {
+ /**
+ * The current [TransitionState]. All values read here are backed by the Snapshot system.
+ *
+ * To observe those values outside of Compose/the Snapshot system, use
+ * [SceneTransitionLayoutState.observableTransitionState] instead.
+ */
+ var transitionState: TransitionState by mutableStateOf(TransitionState.Idle(initialScene))
+ internal set
+}
+
+sealed interface TransitionState {
+ /**
+ * The current effective scene. If a new transition was triggered, it would start from this
+ * scene.
+ *
+ * For instance, when swiping from scene A to scene B, the [currentScene] is A when the swipe
+ * gesture starts, but then if the user flings their finger and commits the transition to scene
+ * B, then [currentScene] becomes scene B even if the transition is not finished yet and is
+ * still animating to settle to scene B.
+ */
+ val currentScene: SceneKey
+
+ /** No transition/animation is currently running. */
+ data class Idle(override val currentScene: SceneKey) : TransitionState
+
+ /**
+ * There is a transition animating between two scenes.
+ *
+ * Important note: [fromScene] and [toScene] might be the same, in which case this [Transition]
+ * should be treated the same as [Idle]. This is designed on purpose so that a [Transition] can
+ * be started without knowing in advance where it is transitioning to, making the logic of
+ * [swipeToScene] easier to reason about.
+ */
+ interface Transition : TransitionState {
+ /** The scene this transition is starting from. */
+ val fromScene: SceneKey
+
+ /** The scene this transition is going to. */
+ val toScene: SceneKey
+
+ /**
+ * The progress of the transition. This is usually in the `[0; 1]` range, but it can also be
+ * less than `0` or greater than `1` when using transitions with a spring AnimationSpec or
+ * when flinging quickly during a swipe gesture.
+ */
+ val progress: Float
+ }
+}
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SceneTransitions.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SceneTransitions.kt
new file mode 100644
index 000000000000..9752f53fbd49
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SceneTransitions.kt
@@ -0,0 +1,176 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene
+
+import androidx.compose.animation.core.AnimationSpec
+import androidx.compose.animation.core.snap
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.unit.IntSize
+import com.android.compose.animation.scene.transformation.AnchoredSize
+import com.android.compose.animation.scene.transformation.AnchoredTranslate
+import com.android.compose.animation.scene.transformation.EdgeTranslate
+import com.android.compose.animation.scene.transformation.Fade
+import com.android.compose.animation.scene.transformation.ModifierTransformation
+import com.android.compose.animation.scene.transformation.PropertyTransformation
+import com.android.compose.animation.scene.transformation.RangedPropertyTransformation
+import com.android.compose.animation.scene.transformation.ScaleSize
+import com.android.compose.animation.scene.transformation.Transformation
+import com.android.compose.animation.scene.transformation.Translate
+import com.android.compose.ui.util.fastForEach
+import com.android.compose.ui.util.fastMap
+
+/** The transitions configuration of a [SceneTransitionLayout]. */
+class SceneTransitions(
+ val transitionSpecs: List<TransitionSpec>,
+) {
+ private val cache = mutableMapOf<SceneKey, MutableMap<SceneKey, TransitionSpec>>()
+
+ internal fun transitionSpec(from: SceneKey, to: SceneKey): TransitionSpec {
+ return cache.getOrPut(from) { mutableMapOf() }.getOrPut(to) { findSpec(from, to) }
+ }
+
+ private fun findSpec(from: SceneKey, to: SceneKey): TransitionSpec {
+ val spec = transition(from, to) { it.from == from && it.to == to }
+ if (spec != null) {
+ return spec
+ }
+
+ val reversed = transition(from, to) { it.from == to && it.to == from }
+ if (reversed != null) {
+ return reversed.reverse()
+ }
+
+ val relaxedSpec =
+ transition(from, to) {
+ (it.from == from && it.to == null) || (it.to == to && it.from == null)
+ }
+ if (relaxedSpec != null) {
+ return relaxedSpec
+ }
+
+ return transition(from, to) {
+ (it.from == to && it.to == null) || (it.to == from && it.from == null)
+ }
+ ?.reverse()
+ ?: defaultTransition(from, to)
+ }
+
+ private fun transition(
+ from: SceneKey,
+ to: SceneKey,
+ filter: (TransitionSpec) -> Boolean,
+ ): TransitionSpec? {
+ var match: TransitionSpec? = null
+ transitionSpecs.fastForEach { spec ->
+ if (filter(spec)) {
+ if (match != null) {
+ error("Found multiple transition specs for transition $from => $to")
+ }
+ match = spec
+ }
+ }
+ return match
+ }
+
+ private fun defaultTransition(from: SceneKey, to: SceneKey) =
+ TransitionSpec(from, to, emptyList(), snap())
+}
+
+/** The definition of a transition between [from] and [to]. */
+data class TransitionSpec(
+ val from: SceneKey?,
+ val to: SceneKey?,
+ val transformations: List<Transformation>,
+ val spec: AnimationSpec<Float>,
+) {
+ private val cache = mutableMapOf<ElementKey, ElementTransformations>()
+
+ internal fun reverse(): TransitionSpec {
+ return copy(
+ from = to,
+ to = from,
+ transformations = transformations.fastMap { it.reverse() },
+ )
+ }
+
+ internal fun transformations(element: ElementKey): ElementTransformations {
+ return cache.getOrPut(element) { computeTransformations(element) }
+ }
+
+ /** Filter [transformations] to compute the [ElementTransformations] of [element]. */
+ private fun computeTransformations(element: ElementKey): ElementTransformations {
+ val modifier = mutableListOf<ModifierTransformation>()
+ var offset: PropertyTransformation<Offset>? = null
+ var size: PropertyTransformation<IntSize>? = null
+ var alpha: PropertyTransformation<Float>? = null
+
+ fun <T> onPropertyTransformation(
+ root: PropertyTransformation<T>,
+ current: PropertyTransformation<T> = root,
+ ) {
+ when (current) {
+ is Translate,
+ is EdgeTranslate,
+ is AnchoredTranslate -> {
+ throwIfNotNull(offset, element, property = "offset")
+ offset = root as PropertyTransformation<Offset>
+ }
+ is ScaleSize,
+ is AnchoredSize -> {
+ throwIfNotNull(size, element, property = "size")
+ size = root as PropertyTransformation<IntSize>
+ }
+ is Fade -> {
+ throwIfNotNull(alpha, element, property = "alpha")
+ alpha = root as PropertyTransformation<Float>
+ }
+ is RangedPropertyTransformation -> onPropertyTransformation(root, current.delegate)
+ }
+ }
+
+ transformations.fastForEach { transformation ->
+ if (!transformation.matcher.matches(element)) {
+ return@fastForEach
+ }
+
+ when (transformation) {
+ is ModifierTransformation -> modifier.add(transformation)
+ is PropertyTransformation<*> -> onPropertyTransformation(transformation)
+ }
+ }
+
+ return ElementTransformations(modifier, offset, size, alpha)
+ }
+
+ private fun throwIfNotNull(
+ previous: PropertyTransformation<*>?,
+ element: ElementKey,
+ property: String,
+ ) {
+ if (previous != null) {
+ error("$element has multiple transformations for its $property property")
+ }
+ }
+}
+
+/** The transformations of an element during a transition. */
+internal class ElementTransformations(
+ val modifier: List<ModifierTransformation>,
+ val offset: PropertyTransformation<Offset>?,
+ val size: PropertyTransformation<IntSize>?,
+ val alpha: PropertyTransformation<Float>?,
+)
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SwipeToScene.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SwipeToScene.kt
new file mode 100644
index 000000000000..d9a45cd663c2
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/SwipeToScene.kt
@@ -0,0 +1,419 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene
+
+import androidx.compose.animation.core.Animatable
+import androidx.compose.animation.core.Spring
+import androidx.compose.animation.core.spring
+import androidx.compose.foundation.gestures.Orientation
+import androidx.compose.foundation.gestures.draggable
+import androidx.compose.foundation.gestures.rememberDraggableState
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableFloatStateOf
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalDensity
+import androidx.compose.ui.unit.dp
+import kotlin.math.absoluteValue
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.launch
+
+/**
+ * Configures the swipeable behavior of a [SceneTransitionLayout] depending on the current state.
+ */
+@Composable
+internal fun Modifier.swipeToScene(
+ layoutImpl: SceneTransitionLayoutImpl,
+ orientation: Orientation,
+): Modifier {
+ val state = layoutImpl.state.transitionState
+ val currentScene = layoutImpl.scene(state.currentScene)
+ val transition = remember {
+ // Note that the currentScene here does not matter, it's only used for initializing the
+ // transition and will be replaced when a drag event starts.
+ SwipeTransition(initialScene = currentScene)
+ }
+
+ val enabled = state == transition || currentScene.shouldEnableSwipes(orientation)
+
+ // Immediately start the drag if this our [transition] is currently animating to a scene (i.e.
+ // the user released their input pointer after swiping in this orientation) and the user can't
+ // swipe in the other direction.
+ val startDragImmediately =
+ state == transition &&
+ transition.isAnimatingOffset &&
+ !currentScene.shouldEnableSwipes(orientation.opposite())
+
+ // The velocity threshold at which the intent of the user is to swipe up or down. It is the same
+ // as SwipeableV2Defaults.VelocityThreshold.
+ val velocityThreshold = with(LocalDensity.current) { 125.dp.toPx() }
+
+ // The positional threshold at which the intent of the user is to swipe to the next scene. It is
+ // the same as SwipeableV2Defaults.PositionalThreshold.
+ val positionalThreshold = with(LocalDensity.current) { 56.dp.toPx() }
+
+ return draggable(
+ orientation = orientation,
+ enabled = enabled,
+ startDragImmediately = startDragImmediately,
+ onDragStarted = { onDragStarted(layoutImpl, transition, orientation) },
+ state =
+ rememberDraggableState { delta -> onDrag(layoutImpl, transition, orientation, delta) },
+ onDragStopped = { velocity ->
+ onDragStopped(
+ layoutImpl,
+ transition,
+ velocity,
+ velocityThreshold,
+ positionalThreshold,
+ )
+ },
+ )
+}
+
+private class SwipeTransition(initialScene: Scene) : TransitionState.Transition {
+ var _currentScene by mutableStateOf(initialScene)
+ override val currentScene: SceneKey
+ get() = _currentScene.key
+
+ var _fromScene by mutableStateOf(initialScene)
+ override val fromScene: SceneKey
+ get() = _fromScene.key
+
+ var _toScene by mutableStateOf(initialScene)
+ override val toScene: SceneKey
+ get() = _toScene.key
+
+ override val progress: Float
+ get() {
+ val offset = if (isAnimatingOffset) offsetAnimatable.value else dragOffset
+ if (distance == 0f) {
+ // This can happen only if fromScene == toScene.
+ error(
+ "Transition.progress should be called only when Transition.fromScene != " +
+ "Transition.toScene"
+ )
+ }
+ return offset / distance
+ }
+
+ /** The current offset caused by the drag gesture. */
+ var dragOffset by mutableFloatStateOf(0f)
+
+ /**
+ * Whether the offset is animated (the user lifted their finger) or if it is driven by gesture.
+ */
+ var isAnimatingOffset by mutableStateOf(false)
+
+ /** The animatable used to animate the offset once the user lifted its finger. */
+ val offsetAnimatable = Animatable(0f, visibilityThreshold = OffsetVisibilityThreshold)
+
+ /**
+ * The job currently animating [offsetAnimatable], if it is animating. Note that setting this to
+ * a new job will automatically cancel the previous one.
+ */
+ var offsetAnimationJob: Job? = null
+ set(value) {
+ field?.cancel()
+ field = value
+ }
+
+ /** The absolute distance between [fromScene] and [toScene]. */
+ var absoluteDistance = 0f
+
+ /**
+ * The signed distance between [fromScene] and [toScene]. It is negative if [fromScene] is above
+ * or to the left of [toScene].
+ */
+ var _distance by mutableFloatStateOf(0f)
+ val distance: Float
+ get() = _distance
+}
+
+/** The destination scene when swiping up or left from [this@upOrLeft]. */
+private fun Scene.upOrLeft(orientation: Orientation): SceneKey? {
+ return when (orientation) {
+ Orientation.Vertical -> userActions[Swipe.Up]
+ Orientation.Horizontal -> userActions[Swipe.Left]
+ }
+}
+
+/** The destination scene when swiping down or right from [this@downOrRight]. */
+private fun Scene.downOrRight(orientation: Orientation): SceneKey? {
+ return when (orientation) {
+ Orientation.Vertical -> userActions[Swipe.Down]
+ Orientation.Horizontal -> userActions[Swipe.Right]
+ }
+}
+
+/** Whether swipe should be enabled in the given [orientation]. */
+private fun Scene.shouldEnableSwipes(orientation: Orientation): Boolean {
+ return upOrLeft(orientation) != null || downOrRight(orientation) != null
+}
+
+private fun Orientation.opposite(): Orientation {
+ return when (this) {
+ Orientation.Vertical -> Orientation.Horizontal
+ Orientation.Horizontal -> Orientation.Vertical
+ }
+}
+
+private fun onDragStarted(
+ layoutImpl: SceneTransitionLayoutImpl,
+ transition: SwipeTransition,
+ orientation: Orientation,
+) {
+ if (layoutImpl.state.transitionState == transition) {
+ // This [transition] was already driving the animation: simply take over it.
+ if (transition.isAnimatingOffset) {
+ // Stop animating and start from where the current offset. Setting the animation job to
+ // `null` will effectively cancel the animation.
+ transition.isAnimatingOffset = false
+ transition.offsetAnimationJob = null
+ transition.dragOffset = transition.offsetAnimatable.value
+ }
+
+ return
+ }
+
+ // TODO(b/290184746): Better handle interruptions here if state != idle.
+
+ val fromScene = layoutImpl.scene(layoutImpl.state.transitionState.currentScene)
+
+ transition._currentScene = fromScene
+ transition._fromScene = fromScene
+
+ // We don't know where we are transitioning to yet given that the drag just started, so set it
+ // to fromScene, which will effectively be treated the same as Idle(fromScene).
+ transition._toScene = fromScene
+
+ transition.dragOffset = 0f
+ transition.isAnimatingOffset = false
+ transition.offsetAnimationJob = null
+
+ // Use the layout size in the swipe orientation for swipe distance.
+ // TODO(b/290184746): Also handle custom distances for transitions. With smaller distances, we
+ // will also have to make sure that we correctly handle overscroll.
+ transition.absoluteDistance =
+ when (orientation) {
+ Orientation.Horizontal -> layoutImpl.size.width
+ Orientation.Vertical -> layoutImpl.size.height
+ }.toFloat()
+
+ if (transition.absoluteDistance > 0f) {
+ layoutImpl.state.transitionState = transition
+ }
+}
+
+private fun onDrag(
+ layoutImpl: SceneTransitionLayoutImpl,
+ transition: SwipeTransition,
+ orientation: Orientation,
+ delta: Float,
+) {
+ transition.dragOffset += delta
+
+ // First check transition.fromScene should be changed for the case where the user quickly swiped
+ // twice in a row to accelerate the transition and go from A => B then B => C really fast.
+ maybeHandleAcceleratedSwipe(transition, orientation)
+
+ val fromScene = transition._fromScene
+ val upOrLeft = fromScene.upOrLeft(orientation)
+ val downOrRight = fromScene.downOrRight(orientation)
+ val offset = transition.dragOffset
+
+ // Compute the target scene depending on the current offset.
+ val targetSceneKey: SceneKey
+ val signedDistance: Float
+ when {
+ offset < 0f && upOrLeft != null -> {
+ targetSceneKey = upOrLeft
+ signedDistance = -transition.absoluteDistance
+ }
+ offset > 0f && downOrRight != null -> {
+ targetSceneKey = downOrRight
+ signedDistance = transition.absoluteDistance
+ }
+ else -> {
+ targetSceneKey = fromScene.key
+ signedDistance = 0f
+ }
+ }
+
+ if (transition._toScene.key != targetSceneKey) {
+ transition._toScene = layoutImpl.scenes.getValue(targetSceneKey)
+ }
+
+ if (transition._distance != signedDistance) {
+ transition._distance = signedDistance
+ }
+}
+
+/**
+ * Change fromScene in the case where the user quickly swiped multiple times in the same direction
+ * to accelerate the transition from A => B then B => C.
+ */
+private fun maybeHandleAcceleratedSwipe(
+ transition: SwipeTransition,
+ orientation: Orientation,
+) {
+ val toScene = transition._toScene
+ val fromScene = transition._fromScene
+
+ // If the swipe was not committed, don't do anything.
+ if (fromScene == toScene || transition._currentScene != toScene) {
+ return
+ }
+
+ // If the offset is past the distance then let's change fromScene so that the user can swipe to
+ // the next screen or go back to the previous one.
+ val offset = transition.dragOffset
+ val absoluteDistance = transition.absoluteDistance
+ if (offset <= -absoluteDistance && fromScene.upOrLeft(orientation) == toScene.key) {
+ transition.dragOffset += absoluteDistance
+ transition._fromScene = toScene
+ } else if (offset >= absoluteDistance && fromScene.downOrRight(orientation) == toScene.key) {
+ transition.dragOffset -= absoluteDistance
+ transition._fromScene = toScene
+ }
+
+ // Important note: toScene and distance will be updated right after this function is called,
+ // using fromScene and dragOffset.
+}
+
+private fun CoroutineScope.onDragStopped(
+ layoutImpl: SceneTransitionLayoutImpl,
+ transition: SwipeTransition,
+ velocity: Float,
+ velocityThreshold: Float,
+ positionalThreshold: Float,
+) {
+ // The state was changed since the drag started; don't do anything.
+ if (layoutImpl.state.transitionState != transition) {
+ return
+ }
+
+ // We were not animating.
+ if (transition._fromScene == transition._toScene) {
+ layoutImpl.state.transitionState = TransitionState.Idle(transition._fromScene.key)
+ return
+ }
+
+ // Compute the destination scene (and therefore offset) to settle in.
+ val targetScene: Scene
+ val targetOffset: Float
+ val offset = transition.dragOffset
+ val distance = transition.distance
+ if (
+ shouldCommitSwipe(
+ offset,
+ distance,
+ velocity,
+ velocityThreshold,
+ positionalThreshold,
+ wasCommitted = transition._currentScene == transition._toScene,
+ )
+ ) {
+ targetOffset = distance
+ targetScene = transition._toScene
+ } else {
+ targetOffset = 0f
+ targetScene = transition._fromScene
+ }
+
+ // If the effective current scene changed, it should be reflected right now in the current scene
+ // state, even before the settle animation is ongoing. That way all the swipeables and back
+ // handlers will be refreshed and the user can for instance quickly swipe vertically from A => B
+ // then horizontally from B => C, or swipe from A => B then immediately go back B => A.
+ if (targetScene != transition._currentScene) {
+ transition._currentScene = targetScene
+ layoutImpl.onChangeScene(targetScene.key)
+ }
+
+ // Animate the offset.
+ transition.offsetAnimationJob = launch {
+ transition.offsetAnimatable.snapTo(offset)
+ transition.isAnimatingOffset = true
+
+ transition.offsetAnimatable.animateTo(
+ targetOffset,
+ // TODO(b/290184746): Make this spring spec configurable.
+ spring(
+ stiffness = Spring.StiffnessMediumLow,
+ visibilityThreshold = OffsetVisibilityThreshold
+ ),
+ initialVelocity = velocity,
+ )
+
+ // Now that the animation is done, the state should be idle. Note that if the state was
+ // changed since this animation started, some external code changed it and we shouldn't do
+ // anything here. Note also that this job will be cancelled in the case where the user
+ // intercepts this swipe.
+ if (layoutImpl.state.transitionState == transition) {
+ layoutImpl.state.transitionState = TransitionState.Idle(targetScene.key)
+ }
+
+ transition.offsetAnimationJob = null
+ }
+}
+
+/**
+ * Whether the swipe to the target scene should be committed or not. This is inspired by
+ * SwipeableV2.computeTarget().
+ */
+private fun shouldCommitSwipe(
+ offset: Float,
+ distance: Float,
+ velocity: Float,
+ velocityThreshold: Float,
+ positionalThreshold: Float,
+ wasCommitted: Boolean,
+): Boolean {
+ fun isCloserToTarget(): Boolean {
+ return (offset - distance).absoluteValue < offset.absoluteValue
+ }
+
+ // Swiping up or left.
+ if (distance < 0f) {
+ return if (offset > 0f || velocity >= velocityThreshold) {
+ false
+ } else {
+ velocity <= -velocityThreshold ||
+ (offset <= -positionalThreshold && !wasCommitted) ||
+ isCloserToTarget()
+ }
+ }
+
+ // Swiping down or right.
+ return if (offset < 0f || velocity <= -velocityThreshold) {
+ false
+ } else {
+ velocity >= velocityThreshold ||
+ (offset >= positionalThreshold && !wasCommitted) ||
+ isCloserToTarget()
+ }
+}
+
+/**
+ * The number of pixels below which there won't be a visible difference in the transition and from
+ * which the animation can stop.
+ */
+private const val OffsetVisibilityThreshold = 0.5f
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/TransitionDsl.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/TransitionDsl.kt
new file mode 100644
index 000000000000..fb12b90d7d3e
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/TransitionDsl.kt
@@ -0,0 +1,194 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene
+
+import androidx.compose.animation.core.AnimationSpec
+import androidx.compose.ui.graphics.RectangleShape
+import androidx.compose.ui.graphics.Shape
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.dp
+
+/** Define the [transitions][SceneTransitions] to be used with a [SceneTransitionLayout]. */
+fun transitions(builder: SceneTransitionsBuilder.() -> Unit): SceneTransitions {
+ return transitionsImpl(builder)
+}
+
+@DslMarker annotation class TransitionDsl
+
+@TransitionDsl
+interface SceneTransitionsBuilder {
+ /**
+ * Define the default animation to be played when transitioning [to] the specified scene, from
+ * any scene. For the animation specification to apply only when transitioning between two
+ * specific scenes, use [from] instead.
+ *
+ * @see from
+ */
+ fun to(
+ to: SceneKey,
+ builder: TransitionBuilder.() -> Unit = {},
+ ): TransitionSpec
+
+ /**
+ * Define the animation to be played when transitioning [from] the specified scene. For the
+ * animation specification to apply only when transitioning between two specific scenes, pass
+ * the destination scene via the [to] argument.
+ *
+ * When looking up which transition should be used when animating from scene A to scene B, we
+ * pick the single transition matching one of these predicates (in order of importance):
+ * 1. from == A && to == B
+ * 2. to == A && from == B, which is then treated in reverse.
+ * 3. (from == A && to == null) || (from == null && to == B)
+ * 4. (from == B && to == null) || (from == null && to == A), which is then treated in reverse.
+ */
+ fun from(
+ from: SceneKey,
+ to: SceneKey? = null,
+ builder: TransitionBuilder.() -> Unit = {},
+ ): TransitionSpec
+}
+
+@TransitionDsl
+interface TransitionBuilder : PropertyTransformationBuilder {
+ /**
+ * The [AnimationSpec] used to animate the progress of this transition from `0` to `1` when
+ * performing programmatic (not input pointer tracking) animations.
+ */
+ var spec: AnimationSpec<Float>
+
+ /**
+ * Define a progress-based range for the transformations inside [builder].
+ *
+ * For instance, the following will fade `Foo` during the first half of the transition then it
+ * will translate it by 100.dp during the second half.
+ *
+ * ```
+ * fractionRange(end = 0.5f) { fade(Foo) }
+ * fractionRange(start = 0.5f) { translate(Foo, x = 100.dp) }
+ * ```
+ *
+ * @param start the start of the range, in the [0; 1] range.
+ * @param end the end of the range, in the [0; 1] range.
+ */
+ fun fractionRange(
+ start: Float? = null,
+ end: Float? = null,
+ builder: PropertyTransformationBuilder.() -> Unit,
+ )
+
+ /**
+ * Define a timestamp-based range for the transformations inside [builder].
+ *
+ * For instance, the following will fade `Foo` during the first half of the transition then it
+ * will translate it by 100.dp during the second half.
+ *
+ * ```
+ * spec = tween(500)
+ * timestampRange(end = 250) { fade(Foo) }
+ * timestampRange(start = 250) { translate(Foo, x = 100.dp) }
+ * ```
+ *
+ * Important: [spec] must be a [androidx.compose.animation.core.DurationBasedAnimationSpec] if
+ * you call [timestampRange], otherwise this will throw. The spec duration will be used to
+ * transform this range into a [fractionRange].
+ *
+ * @param startMillis the start of the range, in the [0; spec.duration] range.
+ * @param endMillis the end of the range, in the [0; spec.duration] range.
+ */
+ fun timestampRange(
+ startMillis: Int? = null,
+ endMillis: Int? = null,
+ builder: PropertyTransformationBuilder.() -> Unit,
+ )
+
+ /**
+ * Punch a hole in the element(s) matching [matcher] that has the same bounds as [bounds] and
+ * using the given [shape].
+ *
+ * Punching a hole in an element will "remove" any pixel drawn by that element in the hole area.
+ * This can be used to make content drawn below an opaque element visible. For example, if we
+ * have [this lockscreen scene](http://shortn/_VYySFnJDhN) drawn below
+ * [this shade scene](http://shortn/_fpxGUk0Rg7) and punch a hole in the latter using the big
+ * clock time bounds and a RoundedCornerShape(10dp), [this](http://shortn/_qt80IvORFj) would be
+ * the result.
+ */
+ fun punchHole(matcher: ElementMatcher, bounds: ElementKey, shape: Shape = RectangleShape)
+}
+
+@TransitionDsl
+interface PropertyTransformationBuilder {
+ /**
+ * Fade the element(s) matching [matcher]. This will automatically fade in or fade out if the
+ * element is entering or leaving the scene, respectively.
+ */
+ fun fade(matcher: ElementMatcher)
+
+ /** Translate the element(s) matching [matcher] by ([x], [y]) dp. */
+ fun translate(matcher: ElementMatcher, x: Dp = 0.dp, y: Dp = 0.dp)
+
+ /**
+ * Translate the element(s) matching [matcher] from/to the [edge] of the [SceneTransitionLayout]
+ * animating it.
+ *
+ * If [startsOutsideLayoutBounds] is `true`, then the element will start completely outside of
+ * the layout bounds (i.e. none of it will be visible at progress = 0f if the layout clips its
+ * content). If it is `false`, then the element will start aligned with the edge of the layout
+ * (i.e. it will be completely visible at progress = 0f).
+ */
+ fun translate(matcher: ElementMatcher, edge: Edge, startsOutsideLayoutBounds: Boolean = true)
+
+ /**
+ * Translate the element(s) matching [matcher] by the same amount that [anchor] is translated
+ * during this transition.
+ *
+ * Note: This currently only works if [anchor] is a shared element of this transition.
+ *
+ * TODO(b/290184746): Also support anchors that are not shared but translated because of other
+ * transformations, like an edge translation.
+ */
+ fun anchoredTranslate(matcher: ElementMatcher, anchor: ElementKey)
+
+ /**
+ * Scale the [width] and [height] of the element(s) matching [matcher]. Note that this scaling
+ * is done during layout, so it will potentially impact the size and position of other elements.
+ *
+ * TODO(b/290184746): Also provide a scaleDrawing() to scale an element at drawing time.
+ */
+ fun scaleSize(matcher: ElementMatcher, width: Float = 1f, height: Float = 1f)
+
+ /**
+ * Scale the element(s) matching [matcher] so that it grows/shrinks to the same size as [anchor]
+ * .
+ *
+ * Note: This currently only works if [anchor] is a shared element of this transition.
+ */
+ fun anchoredSize(matcher: ElementMatcher, anchor: ElementKey)
+}
+
+/** An interface to match one or more elements. */
+interface ElementMatcher {
+ /** Whether the element with key [key] matches this matcher. */
+ fun matches(key: ElementKey): Boolean
+}
+
+/** The edge of a [SceneTransitionLayout]. */
+enum class Edge {
+ Left,
+ Right,
+ Top,
+ Bottom,
+}
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/TransitionDslImpl.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/TransitionDslImpl.kt
new file mode 100644
index 000000000000..afd49b4fde09
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/TransitionDslImpl.kt
@@ -0,0 +1,159 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene
+
+import androidx.compose.animation.core.AnimationSpec
+import androidx.compose.animation.core.DurationBasedAnimationSpec
+import androidx.compose.animation.core.Spring
+import androidx.compose.animation.core.VectorConverter
+import androidx.compose.animation.core.spring
+import androidx.compose.ui.graphics.Shape
+import androidx.compose.ui.unit.Dp
+import com.android.compose.animation.scene.transformation.AnchoredSize
+import com.android.compose.animation.scene.transformation.AnchoredTranslate
+import com.android.compose.animation.scene.transformation.EdgeTranslate
+import com.android.compose.animation.scene.transformation.Fade
+import com.android.compose.animation.scene.transformation.PropertyTransformation
+import com.android.compose.animation.scene.transformation.PunchHole
+import com.android.compose.animation.scene.transformation.RangedPropertyTransformation
+import com.android.compose.animation.scene.transformation.ScaleSize
+import com.android.compose.animation.scene.transformation.Transformation
+import com.android.compose.animation.scene.transformation.TransformationRange
+import com.android.compose.animation.scene.transformation.Translate
+
+internal fun transitionsImpl(
+ builder: SceneTransitionsBuilder.() -> Unit,
+): SceneTransitions {
+ val impl = SceneTransitionsBuilderImpl().apply(builder)
+ return SceneTransitions(impl.transitionSpecs)
+}
+
+private class SceneTransitionsBuilderImpl : SceneTransitionsBuilder {
+ val transitionSpecs = mutableListOf<TransitionSpec>()
+
+ override fun to(to: SceneKey, builder: TransitionBuilder.() -> Unit): TransitionSpec {
+ return transition(from = null, to = to, builder)
+ }
+
+ override fun from(
+ from: SceneKey,
+ to: SceneKey?,
+ builder: TransitionBuilder.() -> Unit
+ ): TransitionSpec {
+ return transition(from = from, to = to, builder)
+ }
+
+ private fun transition(
+ from: SceneKey?,
+ to: SceneKey?,
+ builder: TransitionBuilder.() -> Unit,
+ ): TransitionSpec {
+ val impl = TransitionBuilderImpl().apply(builder)
+ val spec =
+ TransitionSpec(
+ from,
+ to,
+ impl.transformations,
+ impl.spec,
+ )
+ transitionSpecs.add(spec)
+ return spec
+ }
+}
+
+private class TransitionBuilderImpl : TransitionBuilder {
+ val transformations = mutableListOf<Transformation>()
+ override var spec: AnimationSpec<Float> = spring(stiffness = Spring.StiffnessLow)
+
+ private var range: TransformationRange? = null
+ private val durationMillis: Int by lazy {
+ val spec = spec
+ if (spec !is DurationBasedAnimationSpec) {
+ error("timestampRange {} can only be used with a DurationBasedAnimationSpec")
+ }
+
+ spec.vectorize(Float.VectorConverter).durationMillis
+ }
+
+ override fun punchHole(matcher: ElementMatcher, bounds: ElementKey, shape: Shape) {
+ transformations.add(PunchHole(matcher, bounds, shape))
+ }
+
+ override fun fractionRange(
+ start: Float?,
+ end: Float?,
+ builder: PropertyTransformationBuilder.() -> Unit
+ ) {
+ range = TransformationRange(start, end)
+ builder()
+ range = null
+ }
+
+ override fun timestampRange(
+ startMillis: Int?,
+ endMillis: Int?,
+ builder: PropertyTransformationBuilder.() -> Unit
+ ) {
+ if (startMillis != null && (startMillis < 0 || startMillis > durationMillis)) {
+ error("invalid start value: startMillis=$startMillis durationMillis=$durationMillis")
+ }
+
+ if (endMillis != null && (endMillis < 0 || endMillis > durationMillis)) {
+ error("invalid end value: endMillis=$startMillis durationMillis=$durationMillis")
+ }
+
+ val start = startMillis?.let { it.toFloat() / durationMillis }
+ val end = endMillis?.let { it.toFloat() / durationMillis }
+ fractionRange(start, end, builder)
+ }
+
+ private fun transformation(transformation: PropertyTransformation<*>) {
+ if (range != null) {
+ transformations.add(RangedPropertyTransformation(transformation, range!!))
+ } else {
+ transformations.add(transformation)
+ }
+ }
+
+ override fun fade(matcher: ElementMatcher) {
+ transformation(Fade(matcher))
+ }
+
+ override fun translate(matcher: ElementMatcher, x: Dp, y: Dp) {
+ transformation(Translate(matcher, x, y))
+ }
+
+ override fun translate(
+ matcher: ElementMatcher,
+ edge: Edge,
+ startsOutsideLayoutBounds: Boolean
+ ) {
+ transformation(EdgeTranslate(matcher, edge, startsOutsideLayoutBounds))
+ }
+
+ override fun anchoredTranslate(matcher: ElementMatcher, anchor: ElementKey) {
+ transformation(AnchoredTranslate(matcher, anchor))
+ }
+
+ override fun scaleSize(matcher: ElementMatcher, width: Float, height: Float) {
+ transformation(ScaleSize(matcher, width, height))
+ }
+
+ override fun anchoredSize(matcher: ElementMatcher, anchor: ElementKey) {
+ transformation(AnchoredSize(matcher, anchor))
+ }
+}
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/AnchoredSize.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/AnchoredSize.kt
new file mode 100644
index 000000000000..d4ed697f1757
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/AnchoredSize.kt
@@ -0,0 +1,59 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene.transformation
+
+import androidx.compose.ui.unit.IntSize
+import com.android.compose.animation.scene.Element
+import com.android.compose.animation.scene.ElementKey
+import com.android.compose.animation.scene.ElementMatcher
+import com.android.compose.animation.scene.Scene
+import com.android.compose.animation.scene.SceneKey
+import com.android.compose.animation.scene.SceneTransitionLayoutImpl
+import com.android.compose.animation.scene.TransitionState
+
+/** Anchor the size of an element to the size of another element. */
+internal class AnchoredSize(
+ override val matcher: ElementMatcher,
+ private val anchor: ElementKey,
+) : PropertyTransformation<IntSize> {
+ override fun transform(
+ layoutImpl: SceneTransitionLayoutImpl,
+ scene: Scene,
+ element: Element,
+ sceneValues: Element.SceneValues,
+ transition: TransitionState.Transition,
+ value: IntSize,
+ ): IntSize {
+ fun anchorSizeIn(scene: SceneKey): IntSize {
+ val size = layoutImpl.elements[anchor]?.sceneValues?.get(scene)?.size
+ return if (size != null && size != Element.SizeUnspecified) {
+ size
+ } else {
+ value
+ }
+ }
+
+ // This simple implementation assumes that the size of [element] is the same as the size of
+ // the [anchor] in [scene], so simply transform to the size of the anchor in the other
+ // scene.
+ return if (scene.key == transition.fromScene) {
+ anchorSizeIn(transition.toScene)
+ } else {
+ anchorSizeIn(transition.fromScene)
+ }
+ }
+}
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/AnchoredTranslate.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/AnchoredTranslate.kt
new file mode 100644
index 000000000000..8a5bd746dced
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/AnchoredTranslate.kt
@@ -0,0 +1,66 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene.transformation
+
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.geometry.isSpecified
+import com.android.compose.animation.scene.Element
+import com.android.compose.animation.scene.ElementKey
+import com.android.compose.animation.scene.ElementMatcher
+import com.android.compose.animation.scene.Scene
+import com.android.compose.animation.scene.SceneKey
+import com.android.compose.animation.scene.SceneTransitionLayoutImpl
+import com.android.compose.animation.scene.TransitionState
+
+/** Anchor the translation of an element to another element. */
+internal class AnchoredTranslate(
+ override val matcher: ElementMatcher,
+ private val anchor: ElementKey,
+) : PropertyTransformation<Offset> {
+ override fun transform(
+ layoutImpl: SceneTransitionLayoutImpl,
+ scene: Scene,
+ element: Element,
+ sceneValues: Element.SceneValues,
+ transition: TransitionState.Transition,
+ value: Offset,
+ ): Offset {
+ val anchor = layoutImpl.elements[anchor] ?: return value
+ fun anchorOffsetIn(scene: SceneKey): Offset? {
+ return anchor.sceneValues[scene]?.offset?.takeIf { it.isSpecified }
+ }
+
+ // [element] will move the same amount as [anchor] does.
+ // TODO(b/290184746): Also support anchors that are not shared but translated because of
+ // other transformations, like an edge translation.
+ val anchorFromOffset = anchorOffsetIn(transition.fromScene) ?: return value
+ val anchorToOffset = anchorOffsetIn(transition.toScene) ?: return value
+ val offset = anchorToOffset - anchorFromOffset
+
+ return if (scene.key == transition.toScene) {
+ Offset(
+ value.x - offset.x,
+ value.y - offset.y,
+ )
+ } else {
+ Offset(
+ value.x + offset.x,
+ value.y + offset.y,
+ )
+ }
+ }
+}
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/EdgeTranslate.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/EdgeTranslate.kt
new file mode 100644
index 000000000000..5cdce9489772
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/EdgeTranslate.kt
@@ -0,0 +1,74 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene.transformation
+
+import androidx.compose.ui.geometry.Offset
+import com.android.compose.animation.scene.Edge
+import com.android.compose.animation.scene.Element
+import com.android.compose.animation.scene.ElementMatcher
+import com.android.compose.animation.scene.Scene
+import com.android.compose.animation.scene.SceneTransitionLayoutImpl
+import com.android.compose.animation.scene.TransitionState
+
+/** Translate an element from an edge of the layout. */
+internal class EdgeTranslate(
+ override val matcher: ElementMatcher,
+ private val edge: Edge,
+ private val startsOutsideLayoutBounds: Boolean = true,
+) : PropertyTransformation<Offset> {
+ override fun transform(
+ layoutImpl: SceneTransitionLayoutImpl,
+ scene: Scene,
+ element: Element,
+ sceneValues: Element.SceneValues,
+ transition: TransitionState.Transition,
+ value: Offset
+ ): Offset {
+ val sceneSize = scene.size
+ val elementSize = sceneValues.size
+ if (elementSize == Element.SizeUnspecified) {
+ return value
+ }
+
+ return when (edge) {
+ Edge.Top ->
+ if (startsOutsideLayoutBounds) {
+ Offset(value.x, -elementSize.height.toFloat())
+ } else {
+ Offset(value.x, 0f)
+ }
+ Edge.Left ->
+ if (startsOutsideLayoutBounds) {
+ Offset(-elementSize.width.toFloat(), value.y)
+ } else {
+ Offset(0f, value.y)
+ }
+ Edge.Bottom ->
+ if (startsOutsideLayoutBounds) {
+ Offset(value.x, sceneSize.height.toFloat())
+ } else {
+ Offset(value.x, (sceneSize.height - elementSize.height).toFloat())
+ }
+ Edge.Right ->
+ if (startsOutsideLayoutBounds) {
+ Offset(sceneSize.width.toFloat(), value.y)
+ } else {
+ Offset((sceneSize.width - elementSize.width).toFloat(), value.y)
+ }
+ }
+ }
+}
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/Fade.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/Fade.kt
new file mode 100644
index 000000000000..0a5ac5413b38
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/Fade.kt
@@ -0,0 +1,41 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene.transformation
+
+import com.android.compose.animation.scene.Element
+import com.android.compose.animation.scene.ElementMatcher
+import com.android.compose.animation.scene.Scene
+import com.android.compose.animation.scene.SceneTransitionLayoutImpl
+import com.android.compose.animation.scene.TransitionState
+
+/** Fade an element in or out. */
+internal class Fade(
+ override val matcher: ElementMatcher,
+) : PropertyTransformation<Float> {
+ override fun transform(
+ layoutImpl: SceneTransitionLayoutImpl,
+ scene: Scene,
+ element: Element,
+ sceneValues: Element.SceneValues,
+ transition: TransitionState.Transition,
+ value: Float
+ ): Float {
+ // Return the alpha value of [element] either when it starts fading in or when it finished
+ // fading out, which is `0` in both cases.
+ return 0f
+ }
+}
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/PunchHole.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/PunchHole.kt
new file mode 100644
index 000000000000..31e7d7c7c6ba
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/PunchHole.kt
@@ -0,0 +1,91 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene.transformation
+
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.drawWithContent
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.geometry.toRect
+import androidx.compose.ui.graphics.BlendMode
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.Paint
+import androidx.compose.ui.graphics.RectangleShape
+import androidx.compose.ui.graphics.Shape
+import androidx.compose.ui.graphics.drawOutline
+import androidx.compose.ui.graphics.drawscope.DrawScope
+import androidx.compose.ui.graphics.drawscope.drawIntoCanvas
+import androidx.compose.ui.graphics.drawscope.translate
+import androidx.compose.ui.graphics.withSaveLayer
+import androidx.compose.ui.unit.toSize
+import com.android.compose.animation.scene.Element
+import com.android.compose.animation.scene.ElementKey
+import com.android.compose.animation.scene.ElementMatcher
+import com.android.compose.animation.scene.Scene
+import com.android.compose.animation.scene.SceneTransitionLayoutImpl
+
+/** Punch a hole in an element using the bounds of another element and a given [shape]. */
+internal class PunchHole(
+ override val matcher: ElementMatcher,
+ private val bounds: ElementKey,
+ private val shape: Shape,
+) : ModifierTransformation {
+ override fun Modifier.transform(
+ layoutImpl: SceneTransitionLayoutImpl,
+ scene: Scene,
+ element: Element,
+ sceneValues: Element.SceneValues,
+ ): Modifier {
+ return drawWithContent {
+ val bounds = layoutImpl.elements[bounds]
+ if (
+ bounds == null ||
+ bounds.lastSize == Element.SizeUnspecified ||
+ bounds.lastOffset == Offset.Unspecified
+ ) {
+ drawContent()
+ return@drawWithContent
+ }
+
+ drawIntoCanvas { canvas ->
+ canvas.withSaveLayer(size.toRect(), Paint()) {
+ drawContent()
+
+ val offset = bounds.lastOffset - element.lastOffset
+ translate(offset.x, offset.y) { drawHole(bounds) }
+ }
+ }
+ }
+ }
+
+ private fun DrawScope.drawHole(bounds: Element) {
+ if (shape == RectangleShape) {
+ drawRect(Color.Black, blendMode = BlendMode.DstOut)
+ return
+ }
+
+ // TODO(b/290184746): Cache outline if the size of bounds does not change.
+ drawOutline(
+ shape.createOutline(
+ bounds.lastSize.toSize(),
+ layoutDirection,
+ this,
+ ),
+ Color.Black,
+ blendMode = BlendMode.DstOut,
+ )
+ }
+}
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/ScaleSize.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/ScaleSize.kt
new file mode 100644
index 000000000000..ce754dc76adc
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/ScaleSize.kt
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene.transformation
+
+import androidx.compose.ui.unit.IntSize
+import com.android.compose.animation.scene.Element
+import com.android.compose.animation.scene.ElementMatcher
+import com.android.compose.animation.scene.Scene
+import com.android.compose.animation.scene.SceneTransitionLayoutImpl
+import com.android.compose.animation.scene.TransitionState
+import kotlin.math.roundToInt
+
+/**
+ * Scales the size of an element. Note that this makes the element resize every frame and will
+ * therefore impact the layout of other elements.
+ */
+internal class ScaleSize(
+ override val matcher: ElementMatcher,
+ private val width: Float = 1f,
+ private val height: Float = 1f,
+) : PropertyTransformation<IntSize> {
+ override fun transform(
+ layoutImpl: SceneTransitionLayoutImpl,
+ scene: Scene,
+ element: Element,
+ sceneValues: Element.SceneValues,
+ transition: TransitionState.Transition,
+ value: IntSize,
+ ): IntSize {
+ return IntSize(
+ width = (value.width * width).roundToInt(),
+ height = (value.height * height).roundToInt(),
+ )
+ }
+}
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/Transformation.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/Transformation.kt
new file mode 100644
index 000000000000..ce6749da2711
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/Transformation.kt
@@ -0,0 +1,138 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene.transformation
+
+import androidx.compose.ui.Modifier
+import com.android.compose.animation.scene.Element
+import com.android.compose.animation.scene.ElementMatcher
+import com.android.compose.animation.scene.Scene
+import com.android.compose.animation.scene.SceneTransitionLayoutImpl
+import com.android.compose.animation.scene.TransitionState
+
+/** A transformation applied to one or more elements during a transition. */
+sealed interface Transformation {
+ /**
+ * The matcher that should match the element(s) to which this transformation should be applied.
+ */
+ val matcher: ElementMatcher
+
+ /*
+ * Reverse this transformation. This is called when we use Transition(from = A, to = B) when
+ * animating from B to A and there is no Transition(from = B, to = A) defined.
+ */
+ fun reverse(): Transformation = this
+}
+
+/** A transformation that is applied on the element during the whole transition. */
+internal interface ModifierTransformation : Transformation {
+ /** Apply the transformation to [element]. */
+ // TODO(b/290184746): Figure out a public API for custom transformations that don't have access
+ // to these internal classes.
+ fun Modifier.transform(
+ layoutImpl: SceneTransitionLayoutImpl,
+ scene: Scene,
+ element: Element,
+ sceneValues: Element.SceneValues,
+ ): Modifier
+}
+
+/** A transformation that changes the value of an element property, like its size or offset. */
+internal sealed interface PropertyTransformation<T> : Transformation {
+ /**
+ * The range during which the transformation is applied. If it is `null`, then the
+ * transformation will be applied throughout the whole scene transition.
+ */
+ val range: TransformationRange?
+ get() = null
+
+ /**
+ * Transform [value], i.e. the value of the transformed property without this transformation.
+ */
+ // TODO(b/290184746): Figure out a public API for custom transformations that don't have access
+ // to these internal classes.
+ fun transform(
+ layoutImpl: SceneTransitionLayoutImpl,
+ scene: Scene,
+ element: Element,
+ sceneValues: Element.SceneValues,
+ transition: TransitionState.Transition,
+ value: T,
+ ): T
+}
+
+/**
+ * A [PropertyTransformation] associated to a range. This is a helper class so that normal
+ * implementations of [PropertyTransformation] don't have to take care of reversing their range when
+ * they are reversed.
+ */
+internal class RangedPropertyTransformation<T>(
+ val delegate: PropertyTransformation<T>,
+ override val range: TransformationRange,
+) : PropertyTransformation<T> by delegate {
+ override fun reverse(): Transformation {
+ return RangedPropertyTransformation(
+ delegate.reverse() as PropertyTransformation<T>,
+ range.reverse()
+ )
+ }
+}
+
+/** The progress-based range of a [PropertyTransformation]. */
+data class TransformationRange
+private constructor(
+ val start: Float,
+ val end: Float,
+) {
+ constructor(
+ start: Float? = null,
+ end: Float? = null
+ ) : this(start ?: BoundUnspecified, end ?: BoundUnspecified)
+
+ init {
+ require(!start.isSpecified() || (start in 0f..1f))
+ require(!end.isSpecified() || (end in 0f..1f))
+ require(!start.isSpecified() || !end.isSpecified() || start <= end)
+ }
+
+ /** Reverse this range. */
+ fun reverse() = TransformationRange(start = reverseBound(end), end = reverseBound(start))
+
+ /** Get the progress of this range given the global [transitionProgress]. */
+ fun progress(transitionProgress: Float): Float {
+ return when {
+ start.isSpecified() && end.isSpecified() ->
+ ((transitionProgress - start) / (end - start)).coerceIn(0f, 1f)
+ !start.isSpecified() && !end.isSpecified() -> transitionProgress
+ end.isSpecified() -> (transitionProgress / end).coerceAtMost(1f)
+ else -> ((transitionProgress - start) / (1f - start)).coerceAtLeast(0f)
+ }
+ }
+
+ private fun Float.isSpecified() = this != BoundUnspecified
+
+ private fun reverseBound(bound: Float): Float {
+ return if (bound.isSpecified()) {
+ 1f - bound
+ } else {
+ BoundUnspecified
+ }
+ }
+
+ companion object {
+ private const val BoundUnspecified = Float.MIN_VALUE
+ }
+}
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/Translate.kt b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/Translate.kt
new file mode 100644
index 000000000000..8abca61bab20
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/animation/scene/transformation/Translate.kt
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene.transformation
+
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.dp
+import com.android.compose.animation.scene.Element
+import com.android.compose.animation.scene.ElementMatcher
+import com.android.compose.animation.scene.Scene
+import com.android.compose.animation.scene.SceneTransitionLayoutImpl
+import com.android.compose.animation.scene.TransitionState
+
+/** Translate an element by a fixed amount of density-independent pixels. */
+internal class Translate(
+ override val matcher: ElementMatcher,
+ private val x: Dp = 0.dp,
+ private val y: Dp = 0.dp,
+) : PropertyTransformation<Offset> {
+ override fun transform(
+ layoutImpl: SceneTransitionLayoutImpl,
+ scene: Scene,
+ element: Element,
+ sceneValues: Element.SceneValues,
+ transition: TransitionState.Transition,
+ value: Offset,
+ ): Offset {
+ return with(layoutImpl.density) {
+ Offset(
+ value.x + x.toPx(),
+ value.y + y.toPx(),
+ )
+ }
+ }
+}
diff --git a/packages/SystemUI/compose/features/src/com/android/systemui/compose/modifiers/ConditionalModifiers.kt b/packages/SystemUI/compose/core/src/com/android/compose/modifiers/ConditionalModifiers.kt
index 83071d78c64d..135a6e4ec4e4 100644
--- a/packages/SystemUI/compose/features/src/com/android/systemui/compose/modifiers/ConditionalModifiers.kt
+++ b/packages/SystemUI/compose/core/src/com/android/compose/modifiers/ConditionalModifiers.kt
@@ -14,7 +14,7 @@
* limitations under the License.
*/
-package com.android.systemui.compose.modifiers
+package com.android.compose.modifiers
import androidx.compose.ui.Modifier
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/ui/util/ListUtils.kt b/packages/SystemUI/compose/core/src/com/android/compose/ui/util/ListUtils.kt
new file mode 100644
index 000000000000..741f00d9f19b
--- /dev/null
+++ b/packages/SystemUI/compose/core/src/com/android/compose/ui/util/ListUtils.kt
@@ -0,0 +1,55 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.ui.util
+
+import kotlin.contracts.ExperimentalContracts
+import kotlin.contracts.contract
+
+/**
+ * Iterates through a [List] using the index and calls [action] for each item. This does not
+ * allocate an iterator like [Iterable.forEach].
+ *
+ * **Do not use for collections that come from public APIs**, since they may not support random
+ * access in an efficient way, and this method may actually be a lot slower. Only use for
+ * collections that are created by code we control and are known to support random access.
+ */
+@Suppress("BanInlineOptIn")
+@OptIn(ExperimentalContracts::class)
+internal inline fun <T> List<T>.fastForEach(action: (T) -> Unit) {
+ contract { callsInPlace(action) }
+ for (index in indices) {
+ val item = get(index)
+ action(item)
+ }
+}
+
+/**
+ * Returns a list containing the results of applying the given [transform] function to each element
+ * in the original collection.
+ *
+ * **Do not use for collections that come from public APIs**, since they may not support random
+ * access in an efficient way, and this method may actually be a lot slower. Only use for
+ * collections that are created by code we control and are known to support random access.
+ */
+@Suppress("BanInlineOptIn")
+@OptIn(ExperimentalContracts::class)
+internal inline fun <T, R> List<T>.fastMap(transform: (T) -> R): List<R> {
+ contract { callsInPlace(transform) }
+ val target = ArrayList<R>(size)
+ fastForEach { target += transform(it) }
+ return target
+}
diff --git a/packages/SystemUI/compose/core/src/com/android/compose/ui/util/MathHelpers.kt b/packages/SystemUI/compose/core/src/com/android/compose/ui/util/MathHelpers.kt
index c1defb722077..eb1a634ff491 100644
--- a/packages/SystemUI/compose/core/src/com/android/compose/ui/util/MathHelpers.kt
+++ b/packages/SystemUI/compose/core/src/com/android/compose/ui/util/MathHelpers.kt
@@ -17,11 +17,10 @@
package com.android.compose.ui.util
+import androidx.compose.ui.unit.IntSize
import kotlin.math.roundToInt
import kotlin.math.roundToLong
-// TODO(b/272311106): this is a fork from material. Unfork it when MathHelpers.kt reaches material3.
-
/** Linearly interpolate between [start] and [stop] with [fraction] fraction between them. */
fun lerp(start: Float, stop: Float, fraction: Float): Float {
return (1 - fraction) * start + fraction * stop
@@ -36,3 +35,11 @@ fun lerp(start: Int, stop: Int, fraction: Float): Int {
fun lerp(start: Long, stop: Long, fraction: Float): Long {
return start + ((stop - start) * fraction.toDouble()).roundToLong()
}
+
+/** Linearly interpolate between [start] and [stop] with [fraction] fraction between them. */
+fun lerp(start: IntSize, stop: IntSize, fraction: Float): IntSize {
+ return IntSize(
+ lerp(start.width, stop.width, fraction),
+ lerp(start.height, stop.height, fraction)
+ )
+}
diff --git a/packages/SystemUI/compose/core/tests/Android.bp b/packages/SystemUI/compose/core/tests/Android.bp
index 06d94ac5400e..5a8a374b4b7f 100644
--- a/packages/SystemUI/compose/core/tests/Android.bp
+++ b/packages/SystemUI/compose/core/tests/Android.bp
@@ -42,6 +42,8 @@ android_test {
"androidx.compose.runtime_runtime",
"androidx.compose.ui_ui-test-junit4",
"androidx.compose.ui_ui-test-manifest",
+
+ "truth-prebuilt",
],
kotlincflags: ["-Xjvm-default=all"],
diff --git a/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/ObservableTransitionStateTest.kt b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/ObservableTransitionStateTest.kt
new file mode 100644
index 000000000000..04b3f8a1dfe7
--- /dev/null
+++ b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/ObservableTransitionStateTest.kt
@@ -0,0 +1,97 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene
+
+import androidx.compose.ui.test.junit4.createComposeRule
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.google.common.truth.Truth.assertThat
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.runCurrent
+import kotlinx.coroutines.test.runTest
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class ObservableTransitionStateTest {
+ @get:Rule val rule = createComposeRule()
+
+ @Test
+ fun testObservableTransitionState() = runTest {
+ val state = SceneTransitionLayoutState(TestScenes.SceneA)
+
+ // Collect the current observable state into [observableState].
+ // TODO(b/290184746): Use collectValues {} once it is extracted into a library that can be
+ // reused by non-SystemUI testing code.
+ var observableState: ObservableTransitionState? = null
+ backgroundScope.launch {
+ state.observableTransitionState().collect { observableState = it }
+ }
+
+ fun observableState(): ObservableTransitionState {
+ runCurrent()
+ return observableState!!
+ }
+
+ fun ObservableTransitionState.Transition.progress(): Float {
+ var lastProgress = -1f
+ backgroundScope.launch { progress.collect { lastProgress = it } }
+ runCurrent()
+ return lastProgress
+ }
+
+ rule.testTransition(
+ from = TestScenes.SceneA,
+ to = TestScenes.SceneB,
+ transitionLayout = { currentScene, onChangeScene ->
+ SceneTransitionLayout(
+ currentScene,
+ onChangeScene,
+ EmptyTestTransitions,
+ state = state,
+ ) {
+ scene(TestScenes.SceneA) {}
+ scene(TestScenes.SceneB) {}
+ }
+ }
+ ) {
+ before {
+ assertThat(observableState())
+ .isEqualTo(ObservableTransitionState.Idle(TestScenes.SceneA))
+ }
+ at(0) {
+ val state = observableState()
+ assertThat(state).isInstanceOf(ObservableTransitionState.Transition::class.java)
+ assertThat((state as ObservableTransitionState.Transition).fromScene)
+ .isEqualTo(TestScenes.SceneA)
+ assertThat(state.toScene).isEqualTo(TestScenes.SceneB)
+ assertThat(state.progress()).isEqualTo(0f)
+ }
+ at(TestTransitionDuration / 2) {
+ val state = observableState()
+ assertThat((state as ObservableTransitionState.Transition).fromScene)
+ .isEqualTo(TestScenes.SceneA)
+ assertThat(state.toScene).isEqualTo(TestScenes.SceneB)
+ assertThat(state.progress()).isEqualTo(0.5f)
+ }
+ after {
+ assertThat(observableState())
+ .isEqualTo(ObservableTransitionState.Idle(TestScenes.SceneB))
+ }
+ }
+ }
+}
diff --git a/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/SceneTransitionLayoutTest.kt b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/SceneTransitionLayoutTest.kt
new file mode 100644
index 000000000000..8bd654585f29
--- /dev/null
+++ b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/SceneTransitionLayoutTest.kt
@@ -0,0 +1,323 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene
+
+import androidx.activity.ComponentActivity
+import androidx.compose.animation.core.FastOutSlowInEasing
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.offset
+import androidx.compose.foundation.layout.size
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.platform.testTag
+import androidx.compose.ui.test.SemanticsNodeInteraction
+import androidx.compose.ui.test.assertHeightIsEqualTo
+import androidx.compose.ui.test.assertIsDisplayed
+import androidx.compose.ui.test.assertPositionInRootIsEqualTo
+import androidx.compose.ui.test.assertWidthIsEqualTo
+import androidx.compose.ui.test.junit4.createAndroidComposeRule
+import androidx.compose.ui.test.onAllNodesWithTag
+import androidx.compose.ui.test.onChild
+import androidx.compose.ui.test.onFirst
+import androidx.compose.ui.test.onNodeWithTag
+import androidx.compose.ui.test.onNodeWithText
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.DpOffset
+import androidx.compose.ui.unit.IntOffset
+import androidx.compose.ui.unit.dp
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.android.compose.test.subjects.DpOffsetSubject
+import com.android.compose.test.subjects.assertThat
+import com.google.common.truth.Truth.assertThat
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class SceneTransitionLayoutTest {
+ companion object {
+ private val LayoutSize = 300.dp
+ }
+
+ private var currentScene by mutableStateOf(TestScenes.SceneA)
+ private val layoutState = SceneTransitionLayoutState(currentScene)
+
+ // We use createAndroidComposeRule() here and not createComposeRule() because we need an
+ // activity for testBack().
+ @get:Rule val rule = createAndroidComposeRule<ComponentActivity>()
+
+ /** The content under test. */
+ @Composable
+ private fun TestContent() {
+ SceneTransitionLayout(
+ currentScene,
+ { currentScene = it },
+ EmptyTestTransitions,
+ state = layoutState,
+ modifier = Modifier.size(LayoutSize),
+ ) {
+ scene(
+ TestScenes.SceneA,
+ userActions = mapOf(Back to TestScenes.SceneB),
+ ) {
+ Box(Modifier.fillMaxSize()) {
+ SharedFoo(size = 50.dp, childOffset = 0.dp, Modifier.align(Alignment.TopEnd))
+ Text("SceneA")
+ }
+ }
+ scene(TestScenes.SceneB) {
+ Box(Modifier.fillMaxSize()) {
+ SharedFoo(
+ size = 100.dp,
+ childOffset = 50.dp,
+ Modifier.align(Alignment.TopStart),
+ )
+ Text("SceneB")
+ }
+ }
+ scene(TestScenes.SceneC) {
+ Box(Modifier.fillMaxSize()) {
+ SharedFoo(
+ size = 150.dp,
+ childOffset = 100.dp,
+ Modifier.align(Alignment.BottomStart),
+ )
+ Text("SceneC")
+ }
+ }
+ }
+ }
+
+ @Composable
+ private fun SceneScope.SharedFoo(size: Dp, childOffset: Dp, modifier: Modifier = Modifier) {
+ Box(
+ modifier
+ .size(size)
+ .background(Color.Red)
+ .element(TestElements.Foo)
+ .testTag(TestElements.Foo.name)
+ ) {
+ // Offset the single child of Foo by some animated shared offset.
+ val offset by animateSharedDpAsState(childOffset, TestValues.Value1, TestElements.Foo)
+
+ Box(
+ Modifier.offset {
+ val pxOffset = offset.roundToPx()
+ IntOffset(pxOffset, pxOffset)
+ }
+ .size(30.dp)
+ .background(Color.Blue)
+ .testTag(TestElements.Bar.name)
+ )
+ }
+ }
+
+ @Test
+ fun testOnlyCurrentSceneIsDisplayed() {
+ rule.setContent { TestContent() }
+
+ // Only scene A is displayed.
+ rule.onNodeWithText("SceneA").assertIsDisplayed()
+ rule.onNodeWithText("SceneB").assertDoesNotExist()
+ rule.onNodeWithText("SceneC").assertDoesNotExist()
+ assertThat(layoutState.transitionState).isInstanceOf(TransitionState.Idle::class.java)
+ assertThat(layoutState.transitionState.currentScene).isEqualTo(TestScenes.SceneA)
+
+ // Change to scene B. Only that scene is displayed.
+ currentScene = TestScenes.SceneB
+ rule.onNodeWithText("SceneA").assertDoesNotExist()
+ rule.onNodeWithText("SceneB").assertIsDisplayed()
+ rule.onNodeWithText("SceneC").assertDoesNotExist()
+ assertThat(layoutState.transitionState).isInstanceOf(TransitionState.Idle::class.java)
+ assertThat(layoutState.transitionState.currentScene).isEqualTo(TestScenes.SceneB)
+ }
+
+ @Test
+ fun testBack() {
+ rule.setContent { TestContent() }
+
+ assertThat(layoutState.transitionState.currentScene).isEqualTo(TestScenes.SceneA)
+
+ rule.activity.onBackPressed()
+ rule.waitForIdle()
+ assertThat(layoutState.transitionState.currentScene).isEqualTo(TestScenes.SceneB)
+ }
+
+ @Test
+ fun testTransitionState() {
+ rule.setContent { TestContent() }
+ assertThat(layoutState.transitionState).isInstanceOf(TransitionState.Idle::class.java)
+ assertThat(layoutState.transitionState.currentScene).isEqualTo(TestScenes.SceneA)
+
+ // We will advance the clock manually.
+ rule.mainClock.autoAdvance = false
+
+ // Change the current scene. Until composition is triggered, this won't change the layout
+ // state.
+ currentScene = TestScenes.SceneB
+ assertThat(layoutState.transitionState).isInstanceOf(TransitionState.Idle::class.java)
+ assertThat(layoutState.transitionState.currentScene).isEqualTo(TestScenes.SceneA)
+
+ // On the next frame, we will recompose because currentScene changed, which will start the
+ // transition (i.e. it will change the transitionState to be a Transition) in a
+ // LaunchedEffect.
+ rule.mainClock.advanceTimeByFrame()
+ assertThat(layoutState.transitionState).isInstanceOf(TransitionState.Transition::class.java)
+ val transition = layoutState.transitionState as TransitionState.Transition
+ assertThat(transition.fromScene).isEqualTo(TestScenes.SceneA)
+ assertThat(transition.toScene).isEqualTo(TestScenes.SceneB)
+ assertThat(transition.progress).isEqualTo(0f)
+
+ // Then, on the next frame, the animator we started gets its initial value and clock
+ // starting time. We are now at progress = 0f.
+ rule.mainClock.advanceTimeByFrame()
+ assertThat(layoutState.transitionState).isInstanceOf(TransitionState.Transition::class.java)
+ assertThat((layoutState.transitionState as TransitionState.Transition).progress)
+ .isEqualTo(0f)
+
+ // The test transition lasts 480ms. 240ms after the start of the transition, we are at
+ // progress = 0.5f.
+ rule.mainClock.advanceTimeBy(TestTransitionDuration / 2)
+ assertThat(layoutState.transitionState).isInstanceOf(TransitionState.Transition::class.java)
+ assertThat((layoutState.transitionState as TransitionState.Transition).progress)
+ .isEqualTo(0.5f)
+
+ // (240-16) ms later, i.e. one frame before the transition is finished, we are at
+ // progress=(480-16)/480.
+ rule.mainClock.advanceTimeBy(TestTransitionDuration / 2 - 16)
+ assertThat(layoutState.transitionState).isInstanceOf(TransitionState.Transition::class.java)
+ assertThat((layoutState.transitionState as TransitionState.Transition).progress)
+ .isEqualTo((TestTransitionDuration - 16) / 480f)
+
+ // one frame (16ms) later, the transition is finished and we are in the idle state in scene
+ // B.
+ rule.mainClock.advanceTimeByFrame()
+ assertThat(layoutState.transitionState).isInstanceOf(TransitionState.Idle::class.java)
+ assertThat(layoutState.transitionState.currentScene).isEqualTo(TestScenes.SceneB)
+ }
+
+ @Test
+ fun testSharedElement() {
+ rule.setContent { TestContent() }
+
+ // In scene A, the shared element SharedFoo() is at the top end of the layout and has a size
+ // of 50.dp.
+ var sharedFoo = rule.onNodeWithTag(TestElements.Foo.name, useUnmergedTree = true)
+ sharedFoo.assertWidthIsEqualTo(50.dp)
+ sharedFoo.assertHeightIsEqualTo(50.dp)
+ sharedFoo.assertPositionInRootIsEqualTo(
+ expectedTop = 0.dp,
+ expectedLeft = LayoutSize - 50.dp,
+ )
+
+ // The shared offset of the single child of SharedFoo() is 0dp in scene A.
+ assertThat(sharedFoo.onChild().offsetRelativeTo(sharedFoo)).isEqualTo(DpOffset(0.dp, 0.dp))
+
+ // Pause animations to test the state mid-transition.
+ rule.mainClock.autoAdvance = false
+
+ // Go to scene B and let the animation start. See [testLayoutState()] and
+ // [androidx.compose.ui.test.MainTestClock] to understand why we need to advance the clock
+ // by 2 frames to be at the start of the animation.
+ currentScene = TestScenes.SceneB
+ rule.mainClock.advanceTimeByFrame()
+ rule.mainClock.advanceTimeByFrame()
+
+ // Advance to the middle of the animation.
+ rule.mainClock.advanceTimeBy(TestTransitionDuration / 2)
+
+ // We need to use onAllNodesWithTag().onFirst() here given that shared elements are
+ // composed and laid out in both scenes (but drawn only in one).
+ sharedFoo = rule.onAllNodesWithTag(TestElements.Foo.name).onFirst()
+
+ // In scene B, foo is at the top start (x = 0, y = 0) of the layout and has a size of
+ // 100.dp. We pause at the middle of the transition, so it should now be 75.dp given that we
+ // use a linear interpolator. Foo was at (x = layoutSize - 50dp, y = 0) in SceneA and is
+ // going to (x = 0, y = 0), so the offset should now be half what it was.
+ assertThat((layoutState.transitionState as TransitionState.Transition).progress)
+ .isEqualTo(0.5f)
+ sharedFoo.assertWidthIsEqualTo(75.dp)
+ sharedFoo.assertHeightIsEqualTo(75.dp)
+ sharedFoo.assertPositionInRootIsEqualTo(
+ expectedTop = 0.dp,
+ expectedLeft = (LayoutSize - 50.dp) / 2
+ )
+
+ // The shared offset of the single child of SharedFoo() is 50dp in scene B and 0dp in Scene
+ // A, so it should be 25dp now.
+ assertThat(sharedFoo.onChild().offsetRelativeTo(sharedFoo))
+ .isWithin(DpOffsetSubject.DefaultTolerance)
+ .of(DpOffset(25.dp, 25.dp))
+
+ // Animate to scene C, let the animation start then go to the middle of the transition.
+ currentScene = TestScenes.SceneC
+ rule.mainClock.advanceTimeByFrame()
+ rule.mainClock.advanceTimeByFrame()
+ rule.mainClock.advanceTimeBy(TestTransitionDuration / 2)
+
+ // In Scene C, foo is at the bottom start of the layout and has a size of 150.dp. The
+ // transition scene B => scene C is using a FastOutSlowIn interpolator.
+ val interpolatedProgress = FastOutSlowInEasing.transform(0.5f)
+ val expectedTop = (LayoutSize - 150.dp) * interpolatedProgress
+ val expectedLeft = 0.dp
+ val expectedSize = 100.dp + (150.dp - 100.dp) * interpolatedProgress
+
+ sharedFoo = rule.onAllNodesWithTag(TestElements.Foo.name).onFirst()
+ assertThat((layoutState.transitionState as TransitionState.Transition).progress)
+ .isEqualTo(interpolatedProgress)
+ sharedFoo.assertWidthIsEqualTo(expectedSize)
+ sharedFoo.assertHeightIsEqualTo(expectedSize)
+ sharedFoo.assertPositionInRootIsEqualTo(expectedLeft, expectedTop)
+
+ // The shared offset of the single child of SharedFoo() is 50dp in scene B and 100dp in
+ // Scene C.
+ val expectedOffset = 50.dp + (100.dp - 50.dp) * interpolatedProgress
+ assertThat(sharedFoo.onChild().offsetRelativeTo(sharedFoo))
+ .isWithin(DpOffsetSubject.DefaultTolerance)
+ .of(DpOffset(expectedOffset, expectedOffset))
+
+ // Go back to scene A. This should happen instantly (once the animation started, i.e. after
+ // 2 frames) given that we use a snap() animation spec.
+ currentScene = TestScenes.SceneA
+ rule.mainClock.advanceTimeByFrame()
+ rule.mainClock.advanceTimeByFrame()
+ assertThat(layoutState.transitionState).isInstanceOf(TransitionState.Idle::class.java)
+ assertThat(layoutState.transitionState.currentScene).isEqualTo(TestScenes.SceneA)
+ }
+
+ private fun SemanticsNodeInteraction.offsetRelativeTo(
+ other: SemanticsNodeInteraction,
+ ): DpOffset {
+ val node = fetchSemanticsNode()
+ val bounds = node.boundsInRoot
+ val otherBounds = other.fetchSemanticsNode().boundsInRoot
+ return with(node.layoutInfo.density) {
+ DpOffset(
+ x = (bounds.left - otherBounds.left).toDp(),
+ y = (bounds.top - otherBounds.top).toDp(),
+ )
+ }
+ }
+}
diff --git a/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/SwipeToSceneTest.kt b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/SwipeToSceneTest.kt
new file mode 100644
index 000000000000..cb2607a2845e
--- /dev/null
+++ b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/SwipeToSceneTest.kt
@@ -0,0 +1,241 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene
+
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.size
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.platform.LocalViewConfiguration
+import androidx.compose.ui.platform.testTag
+import androidx.compose.ui.test.junit4.createComposeRule
+import androidx.compose.ui.test.onRoot
+import androidx.compose.ui.test.performTouchInput
+import androidx.compose.ui.test.swipeWithVelocity
+import androidx.compose.ui.unit.Density
+import androidx.compose.ui.unit.dp
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.google.common.truth.Truth.assertThat
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class SwipeToSceneTest {
+ companion object {
+ private val LayoutWidth = 200.dp
+ private val LayoutHeight = 400.dp
+
+ /** The middle of the layout, in pixels. */
+ private val Density.middle: Offset
+ get() = Offset((LayoutWidth / 2).toPx(), (LayoutHeight / 2).toPx())
+ }
+
+ private var currentScene by mutableStateOf(TestScenes.SceneA)
+ private val layoutState = SceneTransitionLayoutState(currentScene)
+
+ @get:Rule val rule = createComposeRule()
+
+ /** The content under test. */
+ @Composable
+ private fun TestContent() {
+ SceneTransitionLayout(
+ currentScene,
+ { currentScene = it },
+ EmptyTestTransitions,
+ state = layoutState,
+ modifier = Modifier.size(LayoutWidth, LayoutHeight).testTag(TestElements.Foo.name),
+ ) {
+ scene(
+ TestScenes.SceneA,
+ userActions =
+ mapOf(
+ Swipe.Left to TestScenes.SceneB,
+ Swipe.Down to TestScenes.SceneC,
+ ),
+ ) {
+ Box(Modifier.fillMaxSize())
+ }
+ scene(
+ TestScenes.SceneB,
+ userActions = mapOf(Swipe.Right to TestScenes.SceneA),
+ ) {
+ Box(Modifier.fillMaxSize())
+ }
+ scene(
+ TestScenes.SceneC,
+ userActions = mapOf(Swipe.Down to TestScenes.SceneA),
+ ) {
+ Box(Modifier.fillMaxSize())
+ }
+ }
+ }
+
+ @Test
+ fun testDragWithPositionalThreshold() {
+ // The draggable touch slop, i.e. the min px distance a touch pointer must move before it is
+ // detected as a drag event.
+ var touchSlop = 0f
+ rule.setContent {
+ touchSlop = LocalViewConfiguration.current.touchSlop
+ TestContent()
+ }
+
+ assertThat(layoutState.transitionState).isInstanceOf(TransitionState.Idle::class.java)
+ assertThat(layoutState.transitionState.currentScene).isEqualTo(TestScenes.SceneA)
+
+ // Drag left (i.e. from right to left) by 55dp. We pick 55dp here because 56dp is the
+ // positional threshold from which we commit the gesture.
+ rule.onRoot().performTouchInput {
+ down(middle)
+
+ // We use a high delay so that the velocity of the gesture is slow (otherwise it would
+ // commit the gesture, even if we are below the positional threshold).
+ moveBy(Offset(-55.dp.toPx() - touchSlop, 0f), delayMillis = 1_000)
+ }
+
+ // We should be at a progress = 55dp / LayoutWidth given that we use the layout size in
+ // the gesture axis as swipe distance.
+ var transition = layoutState.transitionState
+ assertThat(transition).isInstanceOf(TransitionState.Transition::class.java)
+ assertThat((transition as TransitionState.Transition).fromScene)
+ .isEqualTo(TestScenes.SceneA)
+ assertThat(transition.toScene).isEqualTo(TestScenes.SceneB)
+ assertThat(transition.currentScene).isEqualTo(TestScenes.SceneA)
+ assertThat(transition.progress).isEqualTo(55.dp / LayoutWidth)
+
+ // Release the finger. We should now be animating back to A (currentScene = SceneA) given
+ // that 55dp < positional threshold.
+ rule.onRoot().performTouchInput { up() }
+ transition = layoutState.transitionState
+ assertThat(transition).isInstanceOf(TransitionState.Transition::class.java)
+ assertThat((transition as TransitionState.Transition).fromScene)
+ .isEqualTo(TestScenes.SceneA)
+ assertThat(transition.toScene).isEqualTo(TestScenes.SceneB)
+ assertThat(transition.currentScene).isEqualTo(TestScenes.SceneA)
+ assertThat(transition.progress).isEqualTo(55.dp / LayoutWidth)
+
+ // Wait for the animation to finish. We should now be in scene A.
+ rule.waitForIdle()
+ assertThat(layoutState.transitionState).isInstanceOf(TransitionState.Idle::class.java)
+ assertThat(layoutState.transitionState.currentScene).isEqualTo(TestScenes.SceneA)
+
+ // Now we do the same but vertically and with a drag distance of 56dp, which is >=
+ // positional threshold.
+ rule.onRoot().performTouchInput {
+ down(middle)
+ moveBy(Offset(0f, 56.dp.toPx() + touchSlop), delayMillis = 1_000)
+ }
+
+ // Drag is in progress, so currentScene = SceneA and progress = 56dp / LayoutHeight
+ transition = layoutState.transitionState
+ assertThat(transition).isInstanceOf(TransitionState.Transition::class.java)
+ assertThat((transition as TransitionState.Transition).fromScene)
+ .isEqualTo(TestScenes.SceneA)
+ assertThat(transition.toScene).isEqualTo(TestScenes.SceneC)
+ assertThat(transition.currentScene).isEqualTo(TestScenes.SceneA)
+ assertThat(transition.progress).isEqualTo(56.dp / LayoutHeight)
+
+ // Release the finger. We should now be animating to C (currentScene = SceneC) given
+ // that 56dp >= positional threshold.
+ rule.onRoot().performTouchInput { up() }
+ transition = layoutState.transitionState
+ assertThat(transition).isInstanceOf(TransitionState.Transition::class.java)
+ assertThat((transition as TransitionState.Transition).fromScene)
+ .isEqualTo(TestScenes.SceneA)
+ assertThat(transition.toScene).isEqualTo(TestScenes.SceneC)
+ assertThat(transition.currentScene).isEqualTo(TestScenes.SceneC)
+ assertThat(transition.progress).isEqualTo(56.dp / LayoutHeight)
+
+ // Wait for the animation to finish. We should now be in scene C.
+ rule.waitForIdle()
+ assertThat(layoutState.transitionState).isInstanceOf(TransitionState.Idle::class.java)
+ assertThat(layoutState.transitionState.currentScene).isEqualTo(TestScenes.SceneC)
+ }
+
+ @Test
+ fun testSwipeWithVelocityThreshold() {
+ // The draggable touch slop, i.e. the min px distance a touch pointer must move before it is
+ // detected as a drag event.
+ var touchSlop = 0f
+ rule.setContent {
+ touchSlop = LocalViewConfiguration.current.touchSlop
+ TestContent()
+ }
+
+ assertThat(layoutState.transitionState).isInstanceOf(TransitionState.Idle::class.java)
+ assertThat(layoutState.transitionState.currentScene).isEqualTo(TestScenes.SceneA)
+
+ // Swipe left (i.e. from right to left) using a velocity of 124 dp/s. We pick 124 dp/s here
+ // because 125 dp/s is the velocity threshold from which we commit the gesture. We also use
+ // a swipe distance < 56dp, the positional threshold, to make sure that we don't commit
+ // the gesture because of a large enough swipe distance.
+ rule.onRoot().performTouchInput {
+ swipeWithVelocity(
+ start = middle,
+ end = middle - Offset(55.dp.toPx() + touchSlop, 0f),
+ endVelocity = 124.dp.toPx(),
+ )
+ }
+
+ // We should be animating back to A (currentScene = SceneA) given that 124 dp/s < velocity
+ // threshold.
+ var transition = layoutState.transitionState
+ assertThat(transition).isInstanceOf(TransitionState.Transition::class.java)
+ assertThat((transition as TransitionState.Transition).fromScene)
+ .isEqualTo(TestScenes.SceneA)
+ assertThat(transition.toScene).isEqualTo(TestScenes.SceneB)
+ assertThat(transition.currentScene).isEqualTo(TestScenes.SceneA)
+ assertThat(transition.progress).isEqualTo(55.dp / LayoutWidth)
+
+ // Wait for the animation to finish. We should now be in scene A.
+ rule.waitForIdle()
+ assertThat(layoutState.transitionState).isInstanceOf(TransitionState.Idle::class.java)
+ assertThat(layoutState.transitionState.currentScene).isEqualTo(TestScenes.SceneA)
+
+ // Now we do the same but vertically and with a swipe velocity of 126dp, which is >
+ // velocity threshold. Note that in theory we could have used 125 dp (= velocity threshold)
+ // but it doesn't work reliably with how swipeWithVelocity() computes move events to get to
+ // the target velocity, probably because of float rounding errors.
+ rule.onRoot().performTouchInput {
+ swipeWithVelocity(
+ start = middle,
+ end = middle + Offset(0f, 55.dp.toPx() + touchSlop),
+ endVelocity = 126.dp.toPx(),
+ )
+ }
+
+ // We should be animating to C (currentScene = SceneC).
+ transition = layoutState.transitionState
+ assertThat(transition).isInstanceOf(TransitionState.Transition::class.java)
+ assertThat((transition as TransitionState.Transition).fromScene)
+ .isEqualTo(TestScenes.SceneA)
+ assertThat(transition.toScene).isEqualTo(TestScenes.SceneC)
+ assertThat(transition.currentScene).isEqualTo(TestScenes.SceneC)
+ assertThat(transition.progress).isEqualTo(55.dp / LayoutHeight)
+
+ // Wait for the animation to finish. We should now be in scene C.
+ rule.waitForIdle()
+ assertThat(layoutState.transitionState).isInstanceOf(TransitionState.Idle::class.java)
+ assertThat(layoutState.transitionState.currentScene).isEqualTo(TestScenes.SceneC)
+ }
+}
diff --git a/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/TestTransition.kt b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/TestTransition.kt
new file mode 100644
index 000000000000..275149a05abf
--- /dev/null
+++ b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/TestTransition.kt
@@ -0,0 +1,217 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene
+
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.test.SemanticsNodeInteraction
+import androidx.compose.ui.test.junit4.ComposeContentTestRule
+import androidx.compose.ui.test.onNodeWithTag
+
+@DslMarker annotation class TransitionTestDsl
+
+@TransitionTestDsl
+interface TransitionTestBuilder {
+ /**
+ * Assert on the state of the layout before the transition starts.
+ *
+ * This should be called maximum once, before [at] or [after] is called.
+ */
+ fun before(builder: TransitionTestAssertionScope.() -> Unit)
+
+ /**
+ * Assert on the state of the layout during the transition at [timestamp].
+ *
+ * This should be called after [before] is called and before [after] is called. Successive calls
+ * to [at] must be called with increasing [timestamp].
+ *
+ * Important: [timestamp] must be a multiple of 16 (the duration of a frame on the JVM/Android).
+ * There is no intermediary state between `t` and `t + 16` , so testing transitions outside of
+ * `t = 0`, `t = 16`, `t = 32`, etc does not make sense.
+ */
+ fun at(timestamp: Long, builder: TransitionTestAssertionScope.() -> Unit)
+
+ /**
+ * Assert on the state of the layout after the transition finished.
+ *
+ * This should be called maximum once, after [before] or [at] is called.
+ */
+ fun after(builder: TransitionTestAssertionScope.() -> Unit)
+}
+
+@TransitionTestDsl
+interface TransitionTestAssertionScope {
+ /** Assert on [element]. */
+ fun onElement(element: ElementKey): SemanticsNodeInteraction
+}
+
+/**
+ * Test the transition between [fromSceneContent] and [toSceneContent] at different points in time.
+ *
+ * @sample com.android.compose.animation.scene.transformation.TranslateTest
+ */
+fun ComposeContentTestRule.testTransition(
+ fromSceneContent: @Composable SceneScope.() -> Unit,
+ toSceneContent: @Composable SceneScope.() -> Unit,
+ transition: TransitionBuilder.() -> Unit,
+ layoutModifier: Modifier = Modifier,
+ builder: TransitionTestBuilder.() -> Unit,
+) {
+ testTransition(
+ from = TestScenes.SceneA,
+ to = TestScenes.SceneB,
+ transitionLayout = { currentScene, onChangeScene ->
+ SceneTransitionLayout(
+ currentScene,
+ onChangeScene,
+ transitions { from(TestScenes.SceneA, to = TestScenes.SceneB, transition) },
+ layoutModifier.fillMaxSize(),
+ ) {
+ scene(TestScenes.SceneA, content = fromSceneContent)
+ scene(TestScenes.SceneB, content = toSceneContent)
+ }
+ },
+ builder,
+ )
+}
+
+/**
+ * Test the transition between two scenes of [transitionLayout][SceneTransitionLayout] at different
+ * points in time.
+ */
+fun ComposeContentTestRule.testTransition(
+ from: SceneKey,
+ to: SceneKey,
+ transitionLayout:
+ @Composable
+ (
+ currentScene: SceneKey,
+ onChangeScene: (SceneKey) -> Unit,
+ ) -> Unit,
+ builder: TransitionTestBuilder.() -> Unit,
+) {
+ val test = transitionTest(builder)
+ val assertionScope =
+ object : TransitionTestAssertionScope {
+ override fun onElement(element: ElementKey): SemanticsNodeInteraction {
+ return this@testTransition.onNodeWithTag(element.name)
+ }
+ }
+
+ var currentScene by mutableStateOf(from)
+ setContent { transitionLayout(currentScene, { currentScene = it }) }
+
+ // Wait for the UI to be idle then test the before state.
+ waitForIdle()
+ test.before(assertionScope)
+
+ // Manually advance the clock to the start of the animation.
+ mainClock.autoAdvance = false
+
+ // Change the current scene.
+ currentScene = to
+
+ // Advance by a frame to trigger recomposition, which will start the transition (i.e. it will
+ // change the transitionState to be a Transition) in a LaunchedEffect.
+ mainClock.advanceTimeByFrame()
+
+ // Advance by another frame so that the animator we started gets its initial value and clock
+ // starting time. We are now at progress = 0f.
+ mainClock.advanceTimeByFrame()
+ waitForIdle()
+
+ // Test the assertions at specific points in time.
+ test.timestamps.forEach { tsAssertion ->
+ if (tsAssertion.timestampDelta > 0L) {
+ mainClock.advanceTimeBy(tsAssertion.timestampDelta)
+ waitForIdle()
+ }
+
+ tsAssertion.assertion(assertionScope)
+ }
+
+ // Go to the end state and test it.
+ mainClock.autoAdvance = true
+ waitForIdle()
+ test.after(assertionScope)
+}
+
+private fun transitionTest(builder: TransitionTestBuilder.() -> Unit): TransitionTest {
+ // Collect the assertion lambdas in [TransitionTest]. Note that the ordering is forced by the
+ // builder, e.g. `before {}` must be called before everything else, then `at {}` (in increasing
+ // order of timestamp), then `after {}`. That way the test code is run with the same order as it
+ // is written, to avoid confusion.
+
+ val impl =
+ object : TransitionTestBuilder {
+ var before: (TransitionTestAssertionScope.() -> Unit)? = null
+ var after: (TransitionTestAssertionScope.() -> Unit)? = null
+ val timestamps = mutableListOf<TimestampAssertion>()
+
+ private var currentTimestamp = 0L
+
+ override fun before(builder: TransitionTestAssertionScope.() -> Unit) {
+ check(before == null) { "before {} must be called maximum once" }
+ check(after == null) { "before {} must be called before after {}" }
+ check(timestamps.isEmpty()) { "before {} must be called before at(...) {}" }
+
+ before = builder
+ }
+
+ override fun at(timestamp: Long, builder: TransitionTestAssertionScope.() -> Unit) {
+ check(after == null) { "at(...) {} must be called before after {}" }
+ check(timestamp >= currentTimestamp) {
+ "at(...) must be called with timestamps in increasing order"
+ }
+ check(timestamp % 16 == 0L) {
+ "timestamp must be a multiple of the frame time (16ms)"
+ }
+
+ val delta = timestamp - currentTimestamp
+ currentTimestamp = timestamp
+
+ timestamps.add(TimestampAssertion(delta, builder))
+ }
+
+ override fun after(builder: TransitionTestAssertionScope.() -> Unit) {
+ check(after == null) { "after {} must be called maximum once" }
+ after = builder
+ }
+ }
+ .apply(builder)
+
+ return TransitionTest(
+ before = impl.before ?: {},
+ timestamps = impl.timestamps,
+ after = impl.after ?: {},
+ )
+}
+
+private class TransitionTest(
+ val before: TransitionTestAssertionScope.() -> Unit,
+ val after: TransitionTestAssertionScope.() -> Unit,
+ val timestamps: List<TimestampAssertion>,
+)
+
+private class TimestampAssertion(
+ val timestampDelta: Long,
+ val assertion: TransitionTestAssertionScope.() -> Unit,
+)
diff --git a/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/TestValues.kt b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/TestValues.kt
new file mode 100644
index 000000000000..83572620c88a
--- /dev/null
+++ b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/TestValues.kt
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene
+
+import androidx.compose.animation.core.FastOutSlowInEasing
+import androidx.compose.animation.core.LinearEasing
+import androidx.compose.animation.core.snap
+import androidx.compose.animation.core.tween
+
+/** Scenes keys that can be reused by tests. */
+object TestScenes {
+ val SceneA = SceneKey("SceneA")
+ val SceneB = SceneKey("SceneB")
+ val SceneC = SceneKey("SceneC")
+}
+
+/** Element keys that can be reused by tests. */
+object TestElements {
+ val Foo = ElementKey("Foo")
+ val Bar = ElementKey("Bar")
+}
+
+/** Value keys that can be reused by tests. */
+object TestValues {
+ val Value1 = ValueKey("Value1")
+}
+
+// We use a transition duration of 480ms here because it is a multiple of 16, the time of a frame in
+// C JVM/Android. Doing so allows us for instance to test the state at progress = 0.5f given that t
+// = 240ms is also a multiple of 16.
+val TestTransitionDuration = 480L
+
+/** A definition of empty transitions between [TestScenes], using different animation specs. */
+val EmptyTestTransitions = transitions {
+ from(TestScenes.SceneA, to = TestScenes.SceneB) {
+ spec = tween(durationMillis = TestTransitionDuration.toInt(), easing = LinearEasing)
+ }
+
+ from(TestScenes.SceneB, to = TestScenes.SceneC) {
+ spec = tween(durationMillis = TestTransitionDuration.toInt(), easing = FastOutSlowInEasing)
+ }
+
+ from(TestScenes.SceneC, to = TestScenes.SceneA) { spec = snap() }
+}
diff --git a/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/AnchoredSizeTest.kt b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/AnchoredSizeTest.kt
new file mode 100644
index 000000000000..8ef6757d33bd
--- /dev/null
+++ b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/AnchoredSizeTest.kt
@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene.transformation
+
+import androidx.compose.animation.core.LinearEasing
+import androidx.compose.animation.core.tween
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.size
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.test.junit4.createComposeRule
+import androidx.compose.ui.unit.dp
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.android.compose.animation.scene.TestElements
+import com.android.compose.animation.scene.testTransition
+import com.android.compose.test.assertSizeIsEqualTo
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class AnchoredSizeTest {
+ @get:Rule val rule = createComposeRule()
+
+ @Test
+ fun testAnchoredSizeEnter() {
+ rule.testTransition(
+ fromSceneContent = { Box(Modifier.size(100.dp, 100.dp).element(TestElements.Foo)) },
+ toSceneContent = {
+ Box(Modifier.size(50.dp, 50.dp).element(TestElements.Foo))
+ Box(Modifier.size(200.dp, 60.dp).element(TestElements.Bar))
+ },
+ transition = {
+ // Scale during 4 frames.
+ spec = tween(16 * 4, easing = LinearEasing)
+ anchoredSize(TestElements.Bar, TestElements.Foo)
+ },
+ ) {
+ // Bar is entering. It starts at the same size as Foo in scene A in and scales to its
+ // final size in scene B.
+ before { onElement(TestElements.Bar).assertDoesNotExist() }
+ at(0) { onElement(TestElements.Bar).assertSizeIsEqualTo(100.dp, 100.dp) }
+ at(16) { onElement(TestElements.Bar).assertSizeIsEqualTo(125.dp, 90.dp) }
+ at(32) { onElement(TestElements.Bar).assertSizeIsEqualTo(150.dp, 80.dp) }
+ at(48) { onElement(TestElements.Bar).assertSizeIsEqualTo(175.dp, 70.dp) }
+ at(64) { onElement(TestElements.Bar).assertSizeIsEqualTo(200.dp, 60.dp) }
+ after { onElement(TestElements.Bar).assertSizeIsEqualTo(200.dp, 60.dp) }
+ }
+ }
+
+ @Test
+ fun testAnchoredSizeExit() {
+ rule.testTransition(
+ fromSceneContent = {
+ Box(Modifier.size(100.dp, 100.dp).element(TestElements.Foo))
+ Box(Modifier.size(100.dp, 100.dp).element(TestElements.Bar))
+ },
+ toSceneContent = { Box(Modifier.size(200.dp, 60.dp).element(TestElements.Foo)) },
+ transition = {
+ // Scale during 4 frames.
+ spec = tween(16 * 4, easing = LinearEasing)
+ anchoredSize(TestElements.Bar, TestElements.Foo)
+ },
+ ) {
+ // Bar is leaving. It starts at 100dp x 100dp in scene A and is scaled to 200dp x 60dp,
+ // the size of Foo in scene B.
+ before { onElement(TestElements.Bar).assertSizeIsEqualTo(100.dp, 100.dp) }
+ at(0) { onElement(TestElements.Bar).assertSizeIsEqualTo(100.dp, 100.dp) }
+ at(16) { onElement(TestElements.Bar).assertSizeIsEqualTo(125.dp, 90.dp) }
+ at(32) { onElement(TestElements.Bar).assertSizeIsEqualTo(150.dp, 80.dp) }
+ at(48) { onElement(TestElements.Bar).assertSizeIsEqualTo(175.dp, 70.dp) }
+ after { onElement(TestElements.Bar).assertDoesNotExist() }
+ }
+ }
+}
diff --git a/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/AnchoredTranslateTest.kt b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/AnchoredTranslateTest.kt
new file mode 100644
index 000000000000..d1205e727cf9
--- /dev/null
+++ b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/AnchoredTranslateTest.kt
@@ -0,0 +1,86 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene.transformation
+
+import androidx.compose.animation.core.LinearEasing
+import androidx.compose.animation.core.tween
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.offset
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.test.assertPositionInRootIsEqualTo
+import androidx.compose.ui.test.junit4.createComposeRule
+import androidx.compose.ui.unit.dp
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.android.compose.animation.scene.TestElements
+import com.android.compose.animation.scene.testTransition
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class AnchoredTranslateTest {
+ @get:Rule val rule = createComposeRule()
+
+ @Test
+ fun testAnchoredTranslateExit() {
+ rule.testTransition(
+ fromSceneContent = {
+ Box(Modifier.offset(10.dp, 50.dp).element(TestElements.Foo))
+ Box(Modifier.offset(20.dp, 40.dp).element(TestElements.Bar))
+ },
+ toSceneContent = { Box(Modifier.offset(30.dp, 10.dp).element(TestElements.Foo)) },
+ transition = {
+ // Anchor Bar to Foo, which is moving from (10dp, 50dp) to (30dp, 10dp).
+ spec = tween(16 * 4, easing = LinearEasing)
+ anchoredTranslate(TestElements.Bar, TestElements.Foo)
+ },
+ ) {
+ // Bar moves by (20dp, -40dp), like Foo.
+ before { onElement(TestElements.Bar).assertPositionInRootIsEqualTo(20.dp, 40.dp) }
+ at(0) { onElement(TestElements.Bar).assertPositionInRootIsEqualTo(20.dp, 40.dp) }
+ at(16) { onElement(TestElements.Bar).assertPositionInRootIsEqualTo(25.dp, 30.dp) }
+ at(32) { onElement(TestElements.Bar).assertPositionInRootIsEqualTo(30.dp, 20.dp) }
+ at(48) { onElement(TestElements.Bar).assertPositionInRootIsEqualTo(35.dp, 10.dp) }
+ after { onElement(TestElements.Bar).assertDoesNotExist() }
+ }
+ }
+
+ @Test
+ fun testAnchoredTranslateEnter() {
+ rule.testTransition(
+ fromSceneContent = { Box(Modifier.offset(10.dp, 50.dp).element(TestElements.Foo)) },
+ toSceneContent = {
+ Box(Modifier.offset(30.dp, 10.dp).element(TestElements.Foo))
+ Box(Modifier.offset(20.dp, 40.dp).element(TestElements.Bar))
+ },
+ transition = {
+ // Anchor Bar to Foo, which is moving from (10dp, 50dp) to (30dp, 10dp).
+ spec = tween(16 * 4, easing = LinearEasing)
+ anchoredTranslate(TestElements.Bar, TestElements.Foo)
+ },
+ ) {
+ // Bar moves by (20dp, -40dp), like Foo.
+ before { onElement(TestElements.Bar).assertDoesNotExist() }
+ at(0) { onElement(TestElements.Bar).assertPositionInRootIsEqualTo(0.dp, 80.dp) }
+ at(16) { onElement(TestElements.Bar).assertPositionInRootIsEqualTo(5.dp, 70.dp) }
+ at(32) { onElement(TestElements.Bar).assertPositionInRootIsEqualTo(10.dp, 60.dp) }
+ at(48) { onElement(TestElements.Bar).assertPositionInRootIsEqualTo(15.dp, 50.dp) }
+ at(64) { onElement(TestElements.Bar).assertPositionInRootIsEqualTo(20.dp, 40.dp) }
+ after { onElement(TestElements.Bar).assertPositionInRootIsEqualTo(20.dp, 40.dp) }
+ }
+ }
+}
diff --git a/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/EdgeTranslateTest.kt b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/EdgeTranslateTest.kt
new file mode 100644
index 000000000000..2a27763f1d5c
--- /dev/null
+++ b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/EdgeTranslateTest.kt
@@ -0,0 +1,153 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene.transformation
+
+import androidx.compose.animation.core.LinearEasing
+import androidx.compose.animation.core.tween
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.size
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.test.assertPositionInRootIsEqualTo
+import androidx.compose.ui.test.junit4.createComposeRule
+import androidx.compose.ui.unit.dp
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.android.compose.animation.scene.Edge
+import com.android.compose.animation.scene.TestElements
+import com.android.compose.animation.scene.TransitionTestBuilder
+import com.android.compose.animation.scene.testTransition
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class EdgeTranslateTest {
+
+ @get:Rule val rule = createComposeRule()
+
+ private fun testEdgeTranslate(
+ edge: Edge,
+ startsOutsideLayoutBounds: Boolean,
+ builder: TransitionTestBuilder.() -> Unit,
+ ) {
+ rule.testTransition(
+ // The layout under test is 300dp x 300dp.
+ layoutModifier = Modifier.size(300.dp),
+ fromSceneContent = {},
+ toSceneContent = {
+ // Foo is 100dp x 100dp in the center of the layout, so at offset = (100dp, 100dp)
+ Box(Modifier.fillMaxSize()) {
+ Box(Modifier.size(100.dp).element(TestElements.Foo).align(Alignment.Center))
+ }
+ },
+ transition = {
+ spec = tween(16 * 4, easing = LinearEasing)
+ translate(TestElements.Foo, edge, startsOutsideLayoutBounds)
+ },
+ builder = builder,
+ )
+ }
+
+ @Test
+ fun testEntersFromTop_startsOutsideLayoutBounds() {
+ testEdgeTranslate(Edge.Top, startsOutsideLayoutBounds = true) {
+ before { onElement(TestElements.Foo).assertDoesNotExist() }
+ at(0) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, (-100).dp) }
+ at(32) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 0.dp) }
+ at(64) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 100.dp) }
+ after { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 100.dp) }
+ }
+ }
+
+ @Test
+ fun testEntersFromTop_startsInsideLayoutBounds() {
+ testEdgeTranslate(Edge.Top, startsOutsideLayoutBounds = false) {
+ before { onElement(TestElements.Foo).assertDoesNotExist() }
+ at(0) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 0.dp) }
+ at(32) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 50.dp) }
+ at(64) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 100.dp) }
+ after { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 100.dp) }
+ }
+ }
+
+ @Test
+ fun testEntersFromBottom_startsOutsideLayoutBounds() {
+ testEdgeTranslate(Edge.Bottom, startsOutsideLayoutBounds = true) {
+ before { onElement(TestElements.Foo).assertDoesNotExist() }
+ at(0) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 300.dp) }
+ at(32) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 200.dp) }
+ at(64) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 100.dp) }
+ after { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 100.dp) }
+ }
+ }
+
+ @Test
+ fun testEntersFromBottom_startsInsideLayoutBounds() {
+ testEdgeTranslate(Edge.Bottom, startsOutsideLayoutBounds = false) {
+ before { onElement(TestElements.Foo).assertDoesNotExist() }
+ at(0) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 200.dp) }
+ at(32) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 150.dp) }
+ at(64) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 100.dp) }
+ after { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 100.dp) }
+ }
+ }
+
+ @Test
+ fun testEntersFromLeft_startsOutsideLayoutBounds() {
+ testEdgeTranslate(Edge.Left, startsOutsideLayoutBounds = true) {
+ before { onElement(TestElements.Foo).assertDoesNotExist() }
+ at(0) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo((-100).dp, 100.dp) }
+ at(32) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(0.dp, 100.dp) }
+ at(64) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 100.dp) }
+ after { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 100.dp) }
+ }
+ }
+
+ @Test
+ fun testEntersFromLeft_startsInsideLayoutBounds() {
+ testEdgeTranslate(Edge.Left, startsOutsideLayoutBounds = false) {
+ before { onElement(TestElements.Foo).assertDoesNotExist() }
+ at(0) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(0.dp, 100.dp) }
+ at(32) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(50.dp, 100.dp) }
+ at(64) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 100.dp) }
+ after { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 100.dp) }
+ }
+ }
+
+ @Test
+ fun testEntersFromRight_startsOutsideLayoutBounds() {
+ testEdgeTranslate(Edge.Right, startsOutsideLayoutBounds = true) {
+ before { onElement(TestElements.Foo).assertDoesNotExist() }
+ at(0) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(300.dp, 100.dp) }
+ at(32) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(200.dp, 100.dp) }
+ at(64) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 100.dp) }
+ after { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 100.dp) }
+ }
+ }
+
+ @Test
+ fun testEntersFromRight_startsInsideLayoutBounds() {
+ testEdgeTranslate(Edge.Right, startsOutsideLayoutBounds = false) {
+ before { onElement(TestElements.Foo).assertDoesNotExist() }
+ at(0) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(200.dp, 100.dp) }
+ at(32) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(150.dp, 100.dp) }
+ at(64) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 100.dp) }
+ after { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(100.dp, 100.dp) }
+ }
+ }
+}
diff --git a/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/ScaleSizeTest.kt b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/ScaleSizeTest.kt
new file mode 100644
index 000000000000..384355ca951f
--- /dev/null
+++ b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/ScaleSizeTest.kt
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene.transformation
+
+import androidx.compose.animation.core.LinearEasing
+import androidx.compose.animation.core.tween
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.size
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.test.junit4.createComposeRule
+import androidx.compose.ui.unit.dp
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.android.compose.animation.scene.TestElements
+import com.android.compose.animation.scene.testTransition
+import com.android.compose.test.assertSizeIsEqualTo
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class ScaleSizeTest {
+ @get:Rule val rule = createComposeRule()
+
+ @Test
+ fun testScaleSize() {
+ rule.testTransition(
+ fromSceneContent = {},
+ toSceneContent = { Box(Modifier.size(100.dp).element(TestElements.Foo)) },
+ transition = {
+ // Scale during 4 frames.
+ spec = tween(16 * 4, easing = LinearEasing)
+ scaleSize(TestElements.Foo, width = 2f, height = 0.5f)
+ },
+ ) {
+ // Foo is entering, is 100dp x 100dp at rest and is scaled by (2, 0.5) during the
+ // transition so it starts at 200dp x 50dp.
+ before { onElement(TestElements.Foo).assertDoesNotExist() }
+ at(0) { onElement(TestElements.Foo).assertSizeIsEqualTo(200.dp, 50.dp) }
+ at(16) { onElement(TestElements.Foo).assertSizeIsEqualTo(175.dp, 62.5.dp) }
+ at(32) { onElement(TestElements.Foo).assertSizeIsEqualTo(150.dp, 75.dp) }
+ at(48) { onElement(TestElements.Foo).assertSizeIsEqualTo(125.dp, 87.5.dp) }
+ at(64) { onElement(TestElements.Foo).assertSizeIsEqualTo(100.dp, 100.dp) }
+ after { onElement(TestElements.Foo).assertSizeIsEqualTo(100.dp, 100.dp) }
+ }
+ }
+}
diff --git a/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/TranslateTest.kt b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/TranslateTest.kt
new file mode 100644
index 000000000000..1d559fd6bd8a
--- /dev/null
+++ b/packages/SystemUI/compose/core/tests/src/com/android/compose/animation/scene/transformation/TranslateTest.kt
@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.animation.scene.transformation
+
+import androidx.compose.animation.core.LinearEasing
+import androidx.compose.animation.core.tween
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.offset
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.test.assertPositionInRootIsEqualTo
+import androidx.compose.ui.test.junit4.createComposeRule
+import androidx.compose.ui.unit.dp
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.android.compose.animation.scene.TestElements
+import com.android.compose.animation.scene.testTransition
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class TranslateTest {
+ @get:Rule val rule = createComposeRule()
+
+ @Test
+ fun testTranslateExit() {
+ rule.testTransition(
+ fromSceneContent = {
+ // Foo is at (10dp, 50dp) and is exiting.
+ Box(Modifier.offset(10.dp, 50.dp).element(TestElements.Foo))
+ },
+ toSceneContent = {},
+ transition = {
+ // Foo is translated by (20dp, -40dp) during 4 frames.
+ spec = tween(16 * 4, easing = LinearEasing)
+ translate(TestElements.Foo, x = 20.dp, y = (-40).dp)
+ },
+ ) {
+ before { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(10.dp, 50.dp) }
+ at(0) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(10.dp, 50.dp) }
+ at(16) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(15.dp, 40.dp) }
+ at(32) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(20.dp, 30.dp) }
+ at(48) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(25.dp, 20.dp) }
+ after { onElement(TestElements.Foo).assertDoesNotExist() }
+ }
+ }
+
+ @Test
+ fun testTranslateEnter() {
+ rule.testTransition(
+ fromSceneContent = {},
+ toSceneContent = {
+ // Foo is entering to (10dp, 50dp)
+ Box(Modifier.offset(10.dp, 50.dp).element(TestElements.Foo))
+ },
+ transition = {
+ // Foo is translated from (10dp, 50) + (20dp, -40dp) during 4 frames.
+ spec = tween(16 * 4, easing = LinearEasing)
+ translate(TestElements.Foo, x = 20.dp, y = (-40).dp)
+ },
+ ) {
+ before { onElement(TestElements.Foo).assertDoesNotExist() }
+ at(0) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(30.dp, 10.dp) }
+ at(16) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(25.dp, 20.dp) }
+ at(32) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(20.dp, 30.dp) }
+ at(48) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(15.dp, 40.dp) }
+ at(64) { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(10.dp, 50.dp) }
+ after { onElement(TestElements.Foo).assertPositionInRootIsEqualTo(10.dp, 50.dp) }
+ }
+ }
+}
diff --git a/packages/SystemUI/compose/core/tests/src/com/android/compose/test/SizeAssertions.kt b/packages/SystemUI/compose/core/tests/src/com/android/compose/test/SizeAssertions.kt
new file mode 100644
index 000000000000..fbd1b512c50a
--- /dev/null
+++ b/packages/SystemUI/compose/core/tests/src/com/android/compose/test/SizeAssertions.kt
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.test
+
+import androidx.compose.ui.test.SemanticsNodeInteraction
+import androidx.compose.ui.test.assertHeightIsEqualTo
+import androidx.compose.ui.test.assertWidthIsEqualTo
+import androidx.compose.ui.unit.Dp
+
+fun SemanticsNodeInteraction.assertSizeIsEqualTo(expectedWidth: Dp, expectedHeight: Dp) {
+ assertWidthIsEqualTo(expectedWidth)
+ assertHeightIsEqualTo(expectedHeight)
+}
diff --git a/packages/SystemUI/compose/core/tests/src/com/android/compose/test/subjects/DpOffsetSubject.kt b/packages/SystemUI/compose/core/tests/src/com/android/compose/test/subjects/DpOffsetSubject.kt
new file mode 100644
index 000000000000..bf7bf98878e6
--- /dev/null
+++ b/packages/SystemUI/compose/core/tests/src/com/android/compose/test/subjects/DpOffsetSubject.kt
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.compose.test.subjects
+
+import androidx.compose.ui.test.assertIsEqualTo
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.DpOffset
+import com.google.common.truth.FailureMetadata
+import com.google.common.truth.Subject
+import com.google.common.truth.Subject.Factory
+import com.google.common.truth.Truth.assertAbout
+
+/** Assert on a [DpOffset]. */
+fun assertThat(dpOffset: DpOffset): DpOffsetSubject {
+ return assertAbout(DpOffsetSubject.dpOffsets()).that(dpOffset)
+}
+
+/** A Truth subject to assert on [DpOffset] with some tolerance. Inspired by FloatSubject. */
+class DpOffsetSubject(
+ metadata: FailureMetadata,
+ private val actual: DpOffset,
+) : Subject(metadata, actual) {
+ fun isWithin(tolerance: Dp): TolerantDpOffsetComparison {
+ return object : TolerantDpOffsetComparison {
+ override fun of(expected: DpOffset) {
+ actual.x.assertIsEqualTo(expected.x, "offset.x", tolerance)
+ actual.y.assertIsEqualTo(expected.y, "offset.y", tolerance)
+ }
+ }
+ }
+
+ interface TolerantDpOffsetComparison {
+ fun of(expected: DpOffset)
+ }
+
+ companion object {
+ val DefaultTolerance = Dp(.5f)
+
+ fun dpOffsets() =
+ Factory<DpOffsetSubject, DpOffset> { metadata, actual ->
+ DpOffsetSubject(metadata, actual)
+ }
+ }
+}
diff --git a/packages/SystemUI/compose/features/src/com/android/systemui/bouncer/ui/composable/PatternBouncer.kt b/packages/SystemUI/compose/features/src/com/android/systemui/bouncer/ui/composable/PatternBouncer.kt
index b3d2e350ed50..63a3eca4695d 100644
--- a/packages/SystemUI/compose/features/src/com/android/systemui/bouncer/ui/composable/PatternBouncer.kt
+++ b/packages/SystemUI/compose/features/src/com/android/systemui/bouncer/ui/composable/PatternBouncer.kt
@@ -43,10 +43,10 @@ import androidx.compose.ui.res.integerResource
import androidx.compose.ui.unit.IntSize
import androidx.compose.ui.unit.dp
import com.android.compose.animation.Easings
+import com.android.compose.modifiers.thenIf
import com.android.internal.R
import com.android.systemui.bouncer.ui.viewmodel.PatternBouncerViewModel
import com.android.systemui.bouncer.ui.viewmodel.PatternDotViewModel
-import com.android.systemui.compose.modifiers.thenIf
import kotlin.math.min
import kotlin.math.pow
import kotlin.math.sqrt
diff --git a/packages/SystemUI/compose/features/src/com/android/systemui/bouncer/ui/composable/PinBouncer.kt b/packages/SystemUI/compose/features/src/com/android/systemui/bouncer/ui/composable/PinBouncer.kt
index 85178bc26a62..bef0b3df36c2 100644
--- a/packages/SystemUI/compose/features/src/com/android/systemui/bouncer/ui/composable/PinBouncer.kt
+++ b/packages/SystemUI/compose/features/src/com/android/systemui/bouncer/ui/composable/PinBouncer.kt
@@ -75,7 +75,7 @@ import androidx.compose.ui.unit.Dp
import androidx.compose.ui.unit.dp
import com.android.compose.animation.Easings
import com.android.compose.grid.VerticalGrid
-import com.android.internal.R.id.image
+import com.android.compose.modifiers.thenIf
import com.android.systemui.R
import com.android.systemui.bouncer.ui.viewmodel.ActionButtonAppearance
import com.android.systemui.bouncer.ui.viewmodel.EnteredKey
@@ -83,7 +83,6 @@ import com.android.systemui.bouncer.ui.viewmodel.PinBouncerViewModel
import com.android.systemui.common.shared.model.ContentDescription
import com.android.systemui.common.shared.model.Icon
import com.android.systemui.common.ui.compose.Icon
-import com.android.systemui.compose.modifiers.thenIf
import kotlin.time.Duration.Companion.milliseconds
import kotlin.time.DurationUnit
import kotlinx.coroutines.async