DSL to define the overscroll behavior of a scene (1/2) (9afe2f0a) · Commits · e / os / android_frameworks_base

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

+57 −9

Original line number	Diff line number	Diff line
		@@ -39,7 +39,6 @@ import androidx.compose.ui.layout.Placeable
		import androidx.compose.ui.node.DrawModifierNode
		import androidx.compose.ui.node.ModifierNodeElement
		import androidx.compose.ui.platform.testTag
		import androidx.compose.ui.semantics.testTag
		import androidx.compose.ui.unit.Constraints
		import androidx.compose.ui.unit.IntSize
		import androidx.compose.ui.unit.round
		@@ -204,6 +203,17 @@ internal class ElementNode(
		measurable: Measurable,
		constraints: Constraints,
		): MeasureResult {
		val overscrollScene = layoutImpl.state.currentOverscrollSpec?.scene
		if (overscrollScene != null && overscrollScene != scene.key) {
		// There is an overscroll in progress on another scene
		// By measuring composable elements, Compose can cache relevant information.
		// This reduces the need for re-measure when users return from an overscroll animation.
		val placeable = measurable.measure(constraints)
		return layout(placeable.width, placeable.height) {
		// We don't want to draw it, no need to place the element.
		}
		}

		val placeable = measure(layoutImpl, scene, element, sceneState, measurable, constraints)
		return layout(placeable.width, placeable.height) {
		place(layoutImpl, scene, element, sceneState, placeable, placementScope = this)
		@@ -253,11 +263,13 @@ private fun shouldDrawElement(
		): Boolean {
		val transition = layoutImpl.state.currentTransition

		// Always draw the element if there is no ongoing transition or if the element is not shared.
		// Always draw the element if there is no ongoing transition or if the element is not shared or
		// if the current scene is the one that is currently over scrolling with [OverscrollSpec].
		if (
		transition == null \|\|
		transition.fromScene !in element.sceneStates \|\|
		transition.toScene !in element.sceneStates
		transition.toScene !in element.sceneStates \|\|
		layoutImpl.state.currentOverscrollSpec?.scene == scene.key
		) {
		return true
		}
		@@ -286,12 +298,14 @@ internal fun shouldDrawOrComposeSharedElement(
		val fromScene = transition.fromScene
		val toScene = transition.toScene

		return scenePicker.sceneDuringTransition(
		val chosenByPicker =
		scenePicker.sceneDuringTransition(
		element = element,
		transition = transition,
		fromSceneZIndex = layoutImpl.scenes.getValue(fromScene).zIndex,
		toSceneZIndex = layoutImpl.scenes.getValue(toScene).zIndex,
		) == scene
		return chosenByPicker \|\| layoutImpl.state.currentOverscrollSpec?.scene == scene
		}

		private fun isSharedElementEnabled(
		@@ -549,6 +563,40 @@ private inline fun <T> computeValue(
		return idleValue
		}

		if (transition is TransitionState.HasOverscrollProperties) {
		val overscroll = layoutImpl.state.currentOverscrollSpec
		if (overscroll?.scene == scene.key) {
		val elementSpec = overscroll.transformationSpec.transformations(element.key, scene.key)
		val propertySpec = transformation(elementSpec) ?: return currentValue()
		val overscrollState = checkNotNull(if (scene.key == toScene) toState else fromState)
		val targetValue =
		propertySpec.transform(
		layoutImpl,
		scene,
		element,
		overscrollState,
		transition,
		idleValue,
		)

		// Make sure we don't read progress if values are the same and we don't need to
		// interpolate, so we don't invalidate the phase where this is read.
		if (targetValue == idleValue) {
		return targetValue
		}

		// TODO(b/290184746): Make sure that we don't overflow transformations associated to a
		// range.
		val directionSign = if (transition.isUpOrLeft) -1 else 1
		val overscrollProgress = transition.progress.let { if (it > 1f) it - 1f else it }
		val progress = directionSign * overscrollProgress
		val rangeProgress = propertySpec.range?.progress(progress) ?: progress

		// Interpolate between the value at rest and the over scrolled value.
		return lerp(idleValue, targetValue, rangeProgress)
		}
		}

		// 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.

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

+5 −3

Original line number	Diff line number	Diff line
		@@ -497,9 +497,11 @@ private class SwipeTransition(
		val _fromScene: Scene,
		val _toScene: Scene,
		private val userActionDistanceScope: UserActionDistanceScope,
		private val orientation: Orientation,
		private val isUpOrLeft: Boolean,
		) : TransitionState.Transition(_fromScene.key, _toScene.key) {
		override val orientation: Orientation,
		override val isUpOrLeft: Boolean,
		) :
		TransitionState.Transition(_fromScene.key, _toScene.key),
		TransitionState.HasOverscrollProperties {
		var _currentScene by mutableStateOf(_fromScene)
		override val currentScene: SceneKey
		get() = _currentScene.key

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

+43 −3

Original line number	Diff line number	Diff line
		@@ -16,6 +16,7 @@

		package com.android.compose.animation.scene

		import androidx.compose.foundation.gestures.Orientation
		import androidx.compose.runtime.Composable
		import androidx.compose.runtime.LaunchedEffect
		import androidx.compose.runtime.SideEffect
		@@ -221,6 +222,23 @@ sealed interface TransitionState {
		isTransitioning(from = other, to = scene)
		}
		}

		interface HasOverscrollProperties {
		/**
		* The position of the [TransitionState.Transition.toScene].
		*
		* Used to understand the direction of the overscroll.
		*/
		val isUpOrLeft: Boolean

		/**
		* The relative orientation between [TransitionState.Transition.fromScene] and
		* [TransitionState.Transition.toScene].
		*
		* Used to understand the orientation of the overscroll.
		*/
		val orientation: Orientation
		}
		}

		internal abstract class BaseSceneTransitionLayoutState(
		@@ -237,6 +255,25 @@ internal abstract class BaseSceneTransitionLayoutState(
		*/
		internal var transformationSpec: TransformationSpecImpl = TransformationSpec.Empty

		private var fromOverscrollSpec: OverscrollSpecImpl? = null
		private var toOverscrollSpec: OverscrollSpecImpl? = null

		/**
		* @return the overscroll [OverscrollSpecImpl] if it is defined for the current
		* [transitionState] and we are currently over scrolling.
		*/
		internal val currentOverscrollSpec: OverscrollSpecImpl?
		get() {
		val transition = currentTransition ?: return null
		if (transition !is TransitionState.HasOverscrollProperties) return null
		val progress = transition.progress
		return when {
		progress < 0f -> fromOverscrollSpec
		progress > 1f -> toOverscrollSpec
		else -> null
		}
		}

		private val activeTransitionLinks = mutableMapOf<StateLink, LinkedTransition>()

		/** Whether we can transition to the given [scene]. */
		@@ -266,10 +303,13 @@ internal abstract class BaseSceneTransitionLayoutState(
		transitionKey: TransitionKey?,
		) {
		// Compute the [TransformationSpec] when the transition starts.
		val fromScene = transition.fromScene
		val toScene = transition.toScene
		val orientation = (transition as? TransitionState.HasOverscrollProperties)?.orientation
		transformationSpec =
		transitions
		.transitionSpec(transition.fromScene, transition.toScene, key = transitionKey)
		.transformationSpec()
		transitions.transitionSpec(fromScene, toScene, key = transitionKey).transformationSpec()
		fromOverscrollSpec = orientation?.let { transitions.overscrollSpec(fromScene, it) }
		toOverscrollSpec = orientation?.let { transitions.overscrollSpec(toScene, it) }
		cancelActiveTransitionLinks()
		setupTransitionLinks(transition)
		transitionState = transition

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

+54 −4

Original line number	Diff line number	Diff line
		@@ -21,6 +21,7 @@ import androidx.compose.animation.core.Spring
		import androidx.compose.animation.core.SpringSpec
		import androidx.compose.animation.core.snap
		import androidx.compose.animation.core.spring
		import androidx.compose.foundation.gestures.Orientation
		import androidx.compose.ui.geometry.Offset
		import androidx.compose.ui.unit.IntSize
		import androidx.compose.ui.util.fastForEach
		@@ -41,18 +42,22 @@ class SceneTransitions
		internal constructor(
		internal val defaultSwipeSpec: SpringSpec<Float>,
		internal val transitionSpecs: List<TransitionSpecImpl>,
		internal val overscrollSpecs: List<OverscrollSpecImpl>,
		) {
		private val cache =
		private val transitionCache =
		mutableMapOf<
		SceneKey, MutableMap<SceneKey, MutableMap<TransitionKey?, TransitionSpecImpl>>
		>()

		private val overscrollCache =
		mutableMapOf<SceneKey, MutableMap<Orientation, OverscrollSpecImpl?>>()

		internal fun transitionSpec(
		from: SceneKey,
		to: SceneKey,
		key: TransitionKey?,
		): TransitionSpecImpl {
		return cache
		return transitionCache
		.getOrPut(from) { mutableMapOf() }
		.getOrPut(to) { mutableMapOf() }
		.getOrPut(key) { findSpec(from, to, key) }
		@@ -105,6 +110,28 @@ internal constructor(
		private fun defaultTransition(from: SceneKey, to: SceneKey) =
		TransitionSpecImpl(key = null, from, to, TransformationSpec.EmptyProvider)

		internal fun overscrollSpec(scene: SceneKey, orientation: Orientation): OverscrollSpecImpl? =
		overscrollCache
		.getOrPut(scene) { mutableMapOf() }
		.getOrPut(orientation) { overscroll(scene, orientation) { it.scene == scene } }

		private fun overscroll(
		scene: SceneKey,
		orientation: Orientation,
		filter: (OverscrollSpecImpl) -> Boolean,
		): OverscrollSpecImpl? {
		var match: OverscrollSpecImpl? = null
		overscrollSpecs.fastForEach { spec ->
		if (spec.orientation == orientation && filter(spec)) {
		if (match != null) {
		error("Found multiple transition specs for transition $scene")
		}
		match = spec
		}
		}
		return match
		}

		companion object {
		internal val DefaultSwipeSpec =
		spring(
		@@ -112,7 +139,12 @@ internal constructor(
		visibilityThreshold = OffsetVisibilityThreshold,
		)

		val Empty = SceneTransitions(DefaultSwipeSpec, transitionSpecs = emptyList())
		val Empty =
		SceneTransitions(
		defaultSwipeSpec = DefaultSwipeSpec,
		transitionSpecs = emptyList(),
		overscrollSpecs = emptyList(),
		)
		}
		}

		@@ -139,7 +171,7 @@ interface TransitionSpec {
		*/
		fun reversed(): TransitionSpec

		/*
		/**
		* The [TransformationSpec] associated to this [TransitionSpec].
		*
		* Note that this is called once every a transition associated to this [TransitionSpec] is
		@@ -212,6 +244,24 @@ internal class TransitionSpecImpl(
		override fun transformationSpec(): TransformationSpecImpl = this.transformationSpec.invoke()
		}

		/** The definition of the overscroll behavior of the [scene]. */
		interface OverscrollSpec {
		/** The scene we are over scrolling. */
		val scene: SceneKey

		/** The orientation of this [OverscrollSpec]. */
		val orientation: Orientation

		/** The [TransformationSpec] associated to this [OverscrollSpec]. */
		val transformationSpec: TransformationSpec
		}

		internal class OverscrollSpecImpl(
		override val scene: SceneKey,
		override val orientation: Orientation,
		override val transformationSpec: TransformationSpecImpl,
		) : OverscrollSpec

		/**
		* An implementation of [TransformationSpec] that allows the quick retrieval of an element
		* [ElementTransformations].

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

+30 −13

Original line number	Diff line number	Diff line
		@@ -18,6 +18,7 @@ package com.android.compose.animation.scene

		import androidx.compose.animation.core.AnimationSpec
		import androidx.compose.animation.core.SpringSpec
		import androidx.compose.foundation.gestures.Orientation
		import androidx.compose.ui.geometry.Offset
		import androidx.compose.ui.unit.Dp
		import androidx.compose.ui.unit.dp
		@@ -72,24 +73,23 @@ interface SceneTransitionsBuilder {
		key: TransitionKey? = null,
		builder: TransitionBuilder.() -> Unit = {},
		): TransitionSpec
		}

		@TransitionDsl
		interface TransitionBuilder : PropertyTransformationBuilder {
		/**
		* The [AnimationSpec] used to animate the associated transition progress from `0` to `1` when
		* the transition is triggered (i.e. it is not gesture-based).
		*/
		var spec: AnimationSpec<Float>

		/**
		* The [SpringSpec] used to animate the associated transition progress when the transition was
		* started by a swipe and is now animating back to a scene because the user lifted their finger.
		* Define the animation to be played when the [scene] is overscrolled in the given
		* [orientation].
		*
		* If `null`, then the [SceneTransitionsBuilder.defaultSwipeSpec] will be used.
		* The overscroll animation always starts from a progress of 0f, and reaches 1f when moving the
		* [distance] down/right, -1f when moving in the opposite direction.
		*/
		var swipeSpec: SpringSpec<Float>?
		fun overscroll(
		scene: SceneKey,
		orientation: Orientation,
		builder: OverscrollBuilder.() -> Unit = {},
		): OverscrollSpec
		}

		@TransitionDsl
		interface OverscrollBuilder : PropertyTransformationBuilder {
		/**
		* The distance it takes for this transition to animate from 0% to 100% when it is driven by a
		* [UserAction].
		@@ -117,6 +117,23 @@ interface TransitionBuilder : PropertyTransformationBuilder {
		end: Float? = null,
		builder: PropertyTransformationBuilder.() -> Unit,
		)
		}

		@TransitionDsl
		interface TransitionBuilder : OverscrollBuilder, PropertyTransformationBuilder {
		/**
		* The [AnimationSpec] used to animate the associated transition progress from `0` to `1` when
		* the transition is triggered (i.e. it is not gesture-based).
		*/
		var spec: AnimationSpec<Float>

		/**
		* The [SpringSpec] used to animate the associated transition progress when the transition was
		* started by a swipe and is now animating back to a scene because the user lifted their finger.
		*
		* If `null`, then the [SceneTransitionsBuilder.defaultSwipeSpec] will be used.
		*/
		var swipeSpec: SpringSpec<Float>?

		/**
		* Define a timestamp-based range for the transformations inside [builder].