Convert interpolated colors to original color space

This CL fixes a crash that can happen when animating a Color using
animateElementColorAsState(): the interpolated Color will end up in the
Oklab color space (instead of the original color space), which is not
supported by the Android platform.

Bug: 382043554
Test: atest AnimatedSharedAsStateTest
Flag: com.android.systemui.scene_container
Change-Id: I6b32af10534f6112560bc174e734c00ce442688b

2 files changed, 16 insertions, 4 deletions

diff --git a/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/AnimateSharedAsState.kt b/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/AnimateSharedAsState.kt
index 0fc88b22a4d0..a4237f36ab58 100644
--- a/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/AnimateSharedAsState.kt
+++ b/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/AnimateSharedAsState.kt
@@ -225,7 +225,7 @@ fun ElementScope<*>.animateElementColorAsState(value: Color, key: ValueKey): Ani
     return animateElementValueAsState(value, key, SharedColorType, canOverflow = false)
 }
 
-private object SharedColorType : SharedValueType<Color, ColorDelta> {
+internal object SharedColorType : SharedValueType<Color, ColorDelta> {
     override val unspecifiedValue: Color = Color.Unspecified
     override val zeroDeltaValue: ColorDelta = ColorDelta(0f, 0f, 0f, 0f)
 
@@ -255,17 +255,17 @@ private object SharedColorType : SharedValueType<Color, ColorDelta> {
                 alpha = aOklab.alpha + b.alpha * bWeight,
                 colorSpace = ColorSpaces.Oklab,
             )
-            .convert(aOklab.colorSpace)
+            .convert(a.colorSpace)
     }
 }
 
 /**
- * Represents the diff between two colors in the same color space.
+ * Represents the diff between two colors in the Oklab color space.
  *
  * Note: This class is necessary because Color() checks the bounds of its values and UncheckedColor
  * is internal.
  */
-private class ColorDelta(val red: Float, val green: Float, val blue: Float, val alpha: Float)
+internal class ColorDelta(val red: Float, val green: Float, val blue: Float, val alpha: Float)
 
 @Composable
 internal fun <T> animateSharedValueAsState(
diff --git a/packages/SystemUI/compose/scene/tests/src/com/android/compose/animation/scene/AnimatedSharedAsStateTest.kt b/packages/SystemUI/compose/scene/tests/src/com/android/compose/animation/scene/AnimatedSharedAsStateTest.kt
index 3644b3069fb3..2fd1d8d8573a 100644
--- a/packages/SystemUI/compose/scene/tests/src/com/android/compose/animation/scene/AnimatedSharedAsStateTest.kt
+++ b/packages/SystemUI/compose/scene/tests/src/com/android/compose/animation/scene/AnimatedSharedAsStateTest.kt
@@ -18,7 +18,10 @@ package com.android.compose.animation.scene
 
 import androidx.compose.animation.core.LinearEasing
 import androidx.compose.animation.core.tween
+import androidx.compose.foundation.background
 import androidx.compose.foundation.gestures.Orientation
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.SideEffect
@@ -495,4 +498,13 @@ class AnimatedSharedAsStateTest {
         assertThat(lastValues[SceneA]).isWithin(0.001f).of(100f)
         assertThat(lastValues[SceneB]).isWithin(0.001f).of(100f)
     }
+
+    @Test
+    fun interpolatedColor() {
+        val a = Color.Red
+        val b = Color.Green
+        val delta = SharedColorType.diff(b, a) // b - a
+        val interpolated = SharedColorType.addWeighted(a, delta, 0.5f) // a + (b - a) * 0.5f
+        rule.setContent { Box(Modifier.fillMaxSize().background(interpolated)) }
+    }
 }