SceneGestureHandler simplification: remove overscroll method (b51f7231) · Commits · e / os / android_frameworks_base

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

+74 −77

Original line number	Diff line number	Diff line
		@@ -196,6 +196,8 @@ class SceneGestureHandler(
		}

		internal fun onDrag(delta: Float) {
		if (delta == 0f) return

		swipeTransition.dragOffset += delta

		// First check transition.fromScene should be changed for the case where the user quickly
		@@ -293,48 +295,77 @@ class SceneGestureHandler(
		return
		}

		fun animateTo(targetScene: Scene, targetOffset: Float) {
		// 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 != swipeTransition._currentScene) {
		swipeTransition._currentScene = targetScene
		layoutImpl.onChangeScene(targetScene.key)
		}

		animateOffset(
		initialVelocity = velocity,
		targetOffset = targetOffset,
		targetScene = targetScene.key
		)
		}

		val fromScene = swipeTransition._fromScene
		if (canChangeScene) {
		// If we are halfway between two scenes, we check what the target will be based on the
		// velocity and offset of the transition, then we launch the animation.

		val toScene = swipeTransition._toScene
		if (fromScene == toScene) {
		// We were not animating.
		if (swipeTransition._fromScene == swipeTransition._toScene) {
		transitionState = TransitionState.Idle(swipeTransition._fromScene.key)
		transitionState = TransitionState.Idle(fromScene.key)
		return
		}

		// Compute the destination scene (and therefore offset) to settle in.
		val targetOffset: Float
		val targetScene: Scene
		val offset = swipeTransition.dragOffset
		val distance = swipeTransition.distance
		if (
		canChangeScene &&
		shouldCommitSwipe(
		offset,
		distance,
		velocity,
		wasCommitted = swipeTransition._currentScene == swipeTransition._toScene,
		wasCommitted = swipeTransition._currentScene == toScene,
		)
		) {
		targetOffset = distance
		targetScene = swipeTransition._toScene
		// Animate to the next scene
		animateTo(targetScene = toScene, targetOffset = distance)
		} else {
		targetOffset = 0f
		targetScene = swipeTransition._fromScene
		// Animate to the initial scene
		animateTo(targetScene = fromScene, targetOffset = 0f)
		}
		} else {
		// We are doing an overscroll animation between scenes. In this case, we can also start
		// from the idle position.

		// 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 != swipeTransition._currentScene) {
		swipeTransition._currentScene = targetScene
		layoutImpl.onChangeScene(targetScene.key)
		}
		val startFromIdlePosition = swipeTransition.dragOffset == 0f

		animateOffset(
		initialVelocity = velocity,
		targetOffset = targetOffset,
		targetScene = targetScene.key
		)
		if (startFromIdlePosition) {
		// If there is a next scene, we start the overscroll animation.
		val target = fromScene.findTargetSceneAndDistance(velocity)
		val isValidTarget = target.distance != 0f && target.sceneKey != fromScene.key
		if (isValidTarget) {
		swipeTransition._toScene = layoutImpl.scene(target.sceneKey)
		swipeTransition._distance = target.distance

		animateTo(targetScene = fromScene, targetOffset = 0f)
		} else {
		// We will not animate
		transitionState = TransitionState.Idle(fromScene.key)
		}
		} else {
		// We were between two scenes: animate to the initial scene.
		animateTo(targetScene = fromScene, targetOffset = 0f)
		}
		}
		}

		/**
		@@ -407,47 +438,6 @@ class SceneGestureHandler(
		}
		}

		internal fun animateOverscroll(velocity: Velocity): Velocity {
		val velocityAmount =
		when (orientation) {
		Orientation.Vertical -> velocity.y
		Orientation.Horizontal -> velocity.x
		}

		if (velocityAmount == 0f) {
		// There is no remaining velocity
		return Velocity.Zero
		}

		val fromScene = currentScene
		val target = fromScene.findTargetSceneAndDistance(velocityAmount)
		val isValidTarget = target.distance != 0f && target.sceneKey != fromScene.key

		if (!isValidTarget \|\| isDrivingTransition) {
		// We have not found a valid target or we are already in a transition
		return Velocity.Zero
		}

		swipeTransition._currentScene = fromScene
		swipeTransition._fromScene = fromScene
		swipeTransition._toScene = layoutImpl.scene(target.sceneKey)
		swipeTransition._distance = target.distance
		swipeTransition.absoluteDistance = target.distance.absoluteValue
		swipeTransition.stopOffsetAnimation()
		swipeTransition.dragOffset = 0f

		transitionState = swipeTransition

		animateOffset(
		initialVelocity = velocityAmount,
		targetOffset = 0f,
		targetScene = fromScene.key
		)

		// The animateOffset animation consumes any remaining velocity.
		return velocity
		}

		private class SwipeTransition(initialScene: Scene) : TransitionState.Transition {
		var _currentScene by mutableStateOf(initialScene)
		override val currentScene: SceneKey
		@@ -623,9 +613,16 @@ class SceneNestedScrollHandler(
		velocityAvailable
		},
		onPostFling = { velocityAvailable ->
		// If there is any velocity left, we can try running an overscroll animation between
		// scenes.
		gestureHandler.animateOverscroll(velocity = velocityAvailable)
		val velocityAmount = velocityAvailable.toAmount()
		if (velocityAmount != 0f) {
		// If there is any velocity left, we can try running an overscroll animation
		// between scenes.
		gestureHandler.onDragStarted()
		gestureHandler.onDragStopped(velocity = velocityAmount, canChangeScene = false)
		}

		// We consumed any remaining velocity.
		velocityAvailable
		},
		)
		}