[flexiglass] Adds gestureFilter lambda to STL

System UI needs a way to be able to filter out drag gestures that start
(e.g. have their first down event) in specific regions on the display.
Please see the next CL on this chain to learn more about why.

This CL adds gestureFilter as a lambda that can be passed to STL and
logic where STL checks with gestureFilter to see whether it should
continue to handle a drag, given its starting position.

Bug: 367447743
Test: manually verified with the next CL
Test: compose tests added
Flag: NONE unused change, next CL is flagged
Change-Id: I081e7628f49681eb4a6d5630e91a0332944736e6

5 files changed, 26 insertions, 0 deletions

diff --git a/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/DraggableHandler.kt b/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/DraggableHandler.kt
index f38a31026664..9891025ad7d3 100644
--- a/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/DraggableHandler.kt
+++ b/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/DraggableHandler.kt
@@ -123,6 +123,10 @@ internal class DraggableHandlerImpl(
         overSlop: Float,
         pointersDown: Int,
     ): DragController {
+        if (startedPosition != null && layoutImpl.gestureFilter(startedPosition)) {
+            return NoOpDragController
+        }
+
         if (overSlop == 0f) {
             val oldDragController = dragController
             check(oldDragController != null && oldDragController.isDrivingTransition) {
diff --git a/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SceneTransitionLayout.kt b/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SceneTransitionLayout.kt
index cec888380513..6e89814a2dc2 100644
--- a/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SceneTransitionLayout.kt
+++ b/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SceneTransitionLayout.kt
@@ -47,6 +47,9 @@ import androidx.compose.ui.unit.LayoutDirection
  * @param state the state of this layout.
  * @param swipeSourceDetector the edge detector used to detect which edge a swipe is started from,
  *   if any.
+ * @param gestureFilter decides whether a drag gesture that started at the given start position
+ *   should be filtered. If the lambda returns `true`, the drag gesture will be ignored. If it
+ *   returns `false`, the drag gesture will be handled.
  * @param transitionInterceptionThreshold used during a scene transition. For the scene to be
  *   intercepted, the progress value must be above the threshold, and below (1 - threshold).
  * @param builder the configuration of the different scenes and overlays of this layout.
@@ -57,6 +60,7 @@ fun SceneTransitionLayout(
     modifier: Modifier = Modifier,
     swipeSourceDetector: SwipeSourceDetector = DefaultEdgeDetector,
     swipeDetector: SwipeDetector = DefaultSwipeDetector,
+    gestureFilter: (startedPosition: Offset) -> Boolean = DefaultGestureFilter,
     @FloatRange(from = 0.0, to = 0.5) transitionInterceptionThreshold: Float = 0.05f,
     builder: SceneTransitionLayoutScope.() -> Unit,
 ) {
@@ -65,6 +69,7 @@ fun SceneTransitionLayout(
         modifier,
         swipeSourceDetector,
         swipeDetector,
+        gestureFilter,
         transitionInterceptionThreshold,
         onLayoutImpl = null,
         builder,
@@ -616,6 +621,7 @@ internal fun SceneTransitionLayoutForTesting(
     modifier: Modifier = Modifier,
     swipeSourceDetector: SwipeSourceDetector = DefaultEdgeDetector,
     swipeDetector: SwipeDetector = DefaultSwipeDetector,
+    gestureFilter: (startedPosition: Offset) -> Boolean = DefaultGestureFilter,
     transitionInterceptionThreshold: Float = 0f,
     onLayoutImpl: ((SceneTransitionLayoutImpl) -> Unit)? = null,
     builder: SceneTransitionLayoutScope.() -> Unit,
@@ -632,6 +638,7 @@ internal fun SceneTransitionLayoutForTesting(
                 transitionInterceptionThreshold = transitionInterceptionThreshold,
                 builder = builder,
                 animationScope = animationScope,
+                gestureFilter = gestureFilter,
             )
             .also { onLayoutImpl?.invoke(it) }
     }
diff --git a/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SceneTransitionLayoutImpl.kt b/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SceneTransitionLayoutImpl.kt
index 65c404387734..9e7be37523f4 100644
--- a/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SceneTransitionLayoutImpl.kt
+++ b/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SceneTransitionLayoutImpl.kt
@@ -31,6 +31,7 @@ import androidx.compose.runtime.snapshots.SnapshotStateMap
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.ExperimentalComposeUiApi
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.layout.ApproachLayoutModifierNode
 import androidx.compose.ui.layout.ApproachMeasureScope
 import androidx.compose.ui.layout.LookaheadScope
@@ -70,6 +71,7 @@ internal class SceneTransitionLayoutImpl(
      * animations.
      */
     internal val animationScope: CoroutineScope,
+    internal val gestureFilter: (startedPosition: Offset) -> Boolean,
 ) {
     /**
      * The map of [Scene]s.
diff --git a/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SwipeDetector.kt b/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SwipeDetector.kt
index 54ee78366875..f758102fee47 100644
--- a/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SwipeDetector.kt
+++ b/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/SwipeDetector.kt
@@ -17,6 +17,7 @@
 package com.android.compose.animation.scene
 
 import androidx.compose.runtime.Stable
+import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.input.pointer.PointerInputChange
 
 /** {@link SwipeDetector} helps determine whether a swipe gestured has occurred. */
@@ -31,6 +32,8 @@ interface SwipeDetector {
 
 val DefaultSwipeDetector = PassthroughSwipeDetector()
 
+val DefaultGestureFilter = { _: Offset -> false }
+
 /** An {@link SwipeDetector} implementation that recognizes a swipe on any input. */
 class PassthroughSwipeDetector : SwipeDetector {
     override fun detectSwipe(change: PointerInputChange): Boolean {
diff --git a/packages/SystemUI/compose/scene/tests/src/com/android/compose/animation/scene/DraggableHandlerTest.kt b/packages/SystemUI/compose/scene/tests/src/com/android/compose/animation/scene/DraggableHandlerTest.kt
index fca92ca804fa..b64b8be90ad2 100644
--- a/packages/SystemUI/compose/scene/tests/src/com/android/compose/animation/scene/DraggableHandlerTest.kt
+++ b/packages/SystemUI/compose/scene/tests/src/com/android/compose/animation/scene/DraggableHandlerTest.kt
@@ -108,6 +108,8 @@ class DraggableHandlerTest {
 
         val transitionInterceptionThreshold = 0.05f
 
+        var gestureFilter: (startedPosition: Offset) -> Boolean = DefaultGestureFilter
+
         private val layoutImpl =
             SceneTransitionLayoutImpl(
                     state = layoutState,
@@ -120,6 +122,7 @@ class DraggableHandlerTest {
                     // Use testScope and not backgroundScope here because backgroundScope does not
                     // work well with advanceUntilIdle(), which is used by some tests.
                     animationScope = testScope,
+                    gestureFilter = { startedPosition -> gestureFilter.invoke(startedPosition) },
                 )
                 .apply { setContentsAndLayoutTargetSizeForTest(LAYOUT_SIZE) }
 
@@ -317,6 +320,13 @@ class DraggableHandlerTest {
     }
 
     @Test
+    fun onDragStarted_doesNotStartTransition_whenGestureFiltered() = runGestureTest {
+        gestureFilter = { _ -> true }
+        onDragStarted(overSlop = down(fractionOfScreen = 0.1f), expectedConsumedOverSlop = 0f)
+        assertIdle(currentScene = SceneA)
+    }
+
+    @Test
     fun afterSceneTransitionIsStarted_interceptDragEvents() = runGestureTest {
         val dragController = onDragStarted(overSlop = down(fractionOfScreen = 0.1f))
         assertTransition(currentScene = SceneA)