Set the target state during lookahead pass (96f26cee) · Commits · e / os / android_frameworks_base

packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/Element.kt

+26 −14

Original line number	Diff line number	Diff line
		@@ -35,6 +35,7 @@ import androidx.compose.ui.layout.ApproachMeasureScope
		import androidx.compose.ui.layout.LayoutCoordinates
		import androidx.compose.ui.layout.Measurable
		import androidx.compose.ui.layout.MeasureResult
		import androidx.compose.ui.layout.MeasureScope
		import androidx.compose.ui.layout.Placeable
		import androidx.compose.ui.node.DrawModifierNode
		import androidx.compose.ui.node.ModifierNodeElement
		@@ -247,13 +248,34 @@ internal class ElementNode(
		}

		@ExperimentalComposeUiApi
		override fun ApproachMeasureScope.approachMeasure(
		override fun MeasureScope.measure(
		measurable: Measurable,
		constraints: Constraints,
		constraints: Constraints
		): MeasureResult {
		check(isLookingAhead)

		return measurable.measure(constraints).run {
		// Update the size this element has in this scene when idle.
		sceneState.targetSize = lookaheadSize
		sceneState.targetSize = size()

		layout(width, height) {
		// Update the offset (relative to the SceneTransitionLayout) this element has in
		// this scene when idle.
		coordinates?.let { coords ->
		with(layoutImpl.lookaheadScope) {
		sceneState.targetOffset =
		lookaheadScopeCoordinates.localLookaheadPositionOf(coords)
		}
		}
		place(0, 0)
		}
		}
		}

		override fun ApproachMeasureScope.approachMeasure(
		measurable: Measurable,
		constraints: Constraints,
		): MeasureResult {
		val transitions = currentTransitions
		val transition = elementTransition(element, transitions)

		@@ -271,16 +293,7 @@ internal class ElementNode(
		val placeable = measurable.measure(constraints)
		sceneState.lastSize = placeable.size()

		return layout(placeable.width, placeable.height) {
		// Update the offset (relative to the SceneTransitionLayout) this element has in
		// this scene when idle.
		coordinates?.let { coords ->
		with(layoutImpl.lookaheadScope) {
		sceneState.targetOffset =
		lookaheadScopeCoordinates.localLookaheadPositionOf(coords)
		}
		}
		}
		return layout(placeable.width, placeable.height) { /* Do not place */ }
		}

		val placeable =
		@@ -808,7 +821,6 @@ private fun Placeable.PlacementScope.place(
		// when idle.
		val coords = coordinates ?: error("Element ${element.key} does not have any coordinates")
		val targetOffsetInScene = lookaheadScopeCoordinates.localLookaheadPositionOf(coords)
		sceneState.targetOffset = targetOffsetInScene

		// No need to place the element in this scene if we don't want to draw it anyways.
		if (!shouldPlaceElement(layoutImpl, scene, element, transition)) {

packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/transformation/AnchoredSize.kt

+14 −9

Original line number	Diff line number	Diff line
		@@ -41,15 +41,20 @@ internal class AnchoredSize(
		value: IntSize,
		): IntSize {
		fun anchorSizeIn(scene: SceneKey): IntSize {
		val size = layoutImpl.elements[anchor]?.sceneStates?.get(scene)?.targetSize
		return if (size != null && size != Element.SizeUnspecified) {
		IntSize(
		val size =
		layoutImpl.elements[anchor]?.sceneStates?.get(scene)?.targetSize?.takeIf {
		it != Element.SizeUnspecified
		}
		?: throwMissingAnchorException(
		transformation = "AnchoredSize",
		anchor = anchor,
		scene = scene,
		)

		return IntSize(
		width = if (anchorWidth) size.width else value.width,
		height = if (anchorHeight) size.height else value.height,
		)
		} else {
		value
		}
		}

		// This simple implementation assumes that the size of [element] is the same as the size of

packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/transformation/AnchoredTranslate.kt

+30 −3

Original line number	Diff line number	Diff line
		@@ -39,7 +39,15 @@ internal class AnchoredTranslate(
		transition: TransitionState.Transition,
		value: Offset,
		): Offset {
		val anchor = layoutImpl.elements[anchor] ?: return value
		fun throwException(scene: SceneKey?): Nothing {
		throwMissingAnchorException(
		transformation = "AnchoredTranslate",
		anchor = anchor,
		scene = scene,
		)
		}

		val anchor = layoutImpl.elements[anchor] ?: throwException(scene = null)
		fun anchorOffsetIn(scene: SceneKey): Offset? {
		return anchor.sceneStates[scene]?.targetOffset?.takeIf { it.isSpecified }
		}
		@@ -47,8 +55,10 @@ internal class AnchoredTranslate(
		// [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 anchorFromOffset =
		anchorOffsetIn(transition.fromScene) ?: throwException(transition.fromScene)
		val anchorToOffset =
		anchorOffsetIn(transition.toScene) ?: throwException(transition.toScene)
		val offset = anchorToOffset - anchorFromOffset

		return if (scene.key == transition.toScene) {
		@@ -64,3 +74,20 @@ internal class AnchoredTranslate(
		}
		}
		}

		internal fun throwMissingAnchorException(
		transformation: String,
		anchor: ElementKey,
		scene: SceneKey?,
		): Nothing {
		error(
		"""
		Anchor ${anchor.debugName} does not have a target state in scene ${scene?.debugName}.
		This either means that it was not composed at all during the transition or that it was
		composed too late, for instance during layout/subcomposition. To avoid flickers in
		$transformation, you should make sure that the composition and layout of anchor is not
		deferred, for instance by moving it out of lazy layouts.
		"""
		.trimIndent()
		)
		}

packages/SystemUI/compose/scene/tests/src/com/android/compose/animation/scene/transformation/AnchoredTranslateTest.kt

+25 −0

Original line number	Diff line number	Diff line
		@@ -27,6 +27,7 @@ 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.animation.scene.transition
		import org.junit.Rule
		import org.junit.Test
		import org.junit.runner.RunWith
		@@ -83,4 +84,28 @@ class AnchoredTranslateTest {
		after { onElement(TestElements.Bar).assertPositionInRootIsEqualTo(20.dp, 40.dp) }
		}
		}

		@Test
		fun anchorPlacedAfterAnchoredElement() {
		rule.testTransition(
		fromSceneContent = { Box(Modifier.offset(10.dp, 50.dp).element(TestElements.Foo)) },
		toSceneContent = {
		Box(Modifier.offset(20.dp, 40.dp).element(TestElements.Bar))
		Box(Modifier.offset(30.dp, 10.dp).element(TestElements.Foo))
		},
		transition = {
		spec = tween(16 * 4, easing = LinearEasing)
		anchoredTranslate(TestElements.Bar, TestElements.Foo)
		},
		) {
		// No exception is thrown even if Bar is placed before the anchor in toScene.
		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) }
		}
		}
		}