Simplify DraggableHandlerImpl.onDrag() (9f7ef863) · Commits · e / os / android_frameworks_base

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

+72 −66

Original line number	Diff line number	Diff line
		@@ -284,17 +284,54 @@ private class DragControllerImpl(
		if (delta == 0f \|\| !isDrivingTransition \|\| swipeTransition.isFinishing) {
		return 0f
		}
		swipeTransition.dragOffset += delta

		val (fromScene, acceleratedOffset) =
		computeFromSceneConsideringAcceleratedSwipe(swipeTransition)
		val toScene = swipeTransition._toScene
		val distance = swipeTransition.distance()
		val desiredOffset = swipeTransition.dragOffset + delta

		fun hasReachedToSceneUpOrLeft() =
		distance < 0 &&
		desiredOffset <= distance &&
		swipes.upOrLeftResult?.toScene == toScene.key

		fun hasReachedToSceneDownOrRight() =
		distance > 0 &&
		desiredOffset >= distance &&
		swipes.downOrRightResult?.toScene == toScene.key

		// Considering accelerated swipe: Change fromScene in the case where the user quickly swiped
		// multiple times in the same direction to accelerate the transition from A => B then B => C
		//
		// TODO(b/290184746): the second drag needs to pass B to work. Add support for flinging
		// twice before B has been reached
		val hasReachedToScene =
		swipeTransition._currentScene == toScene &&
		(hasReachedToSceneUpOrLeft() \|\| hasReachedToSceneDownOrRight())

		val fromScene: Scene
		val currentTransitionOffset: Float
		val newOffset: Float
		if (hasReachedToScene) {
		// The new transition will start from the current toScene
		fromScene = toScene
		// The current transition is completed (we have reached the distance)
		currentTransitionOffset = distance
		// The next transition will start with the remaining offset
		newOffset = desiredOffset - distance
		} else {
		fromScene = swipeTransition._fromScene
		currentTransitionOffset = desiredOffset
		// If there is a new transition, we will use the same offset
		newOffset = currentTransitionOffset
		}

		swipeTransition.dragOffset = currentTransitionOffset

		val isNewFromScene = fromScene.key != swipeTransition.fromScene
		val result =
		swipes.findUserActionResult(
		fromScene = fromScene,
		directionOffset = swipeTransition.dragOffset,
		updateSwipesResults = isNewFromScene,
		directionOffset = newOffset,
		updateSwipesResults = hasReachedToScene
		)

		if (result == null) {
		@@ -302,15 +339,16 @@ private class DragControllerImpl(
		return 0f
		}

		if (
		isNewFromScene \|\|
		val needNewTransition =
		hasReachedToScene \|\|
		result.toScene != swipeTransition.toScene \|\|
		result.transitionKey != swipeTransition.key
		) {

		if (needNewTransition) {
		// Make sure the current transition will finish to the right current scene.
		swipeTransition._currentScene = fromScene

		val swipeTransition =
		val newSwipeTransition =
		SwipeTransition(
		layoutState = layoutState,
		coroutineScope = draggableHandler.coroutineScope,
		@@ -320,49 +358,13 @@ private class DragControllerImpl(
		layoutImpl = draggableHandler.layoutImpl,
		orientation = draggableHandler.orientation,
		)
		.apply { dragOffset = swipeTransition.dragOffset + acceleratedOffset }

		updateTransition(swipeTransition)
		newSwipeTransition.dragOffset = newOffset
		updateTransition(newSwipeTransition)
		}

		return delta
		}

		/**
		* Change fromScene in the case where the user quickly swiped multiple times in the same
		* direction to accelerate the transition from A => B then B => C.
		*
		* @return the new fromScene and a dragOffset to be added in case the scene has changed
		*
		* TODO(b/290184746): the second drag needs to pass B to work. Add support for flinging twice
		* before B has been reached
		*/
		private inline fun computeFromSceneConsideringAcceleratedSwipe(
		swipeTransition: SwipeTransition,
		): Pair<Scene, Float> {
		val toScene = swipeTransition._toScene
		val fromScene = swipeTransition._fromScene
		val distance = swipeTransition.distance()

		// If the swipe was not committed or if the swipe distance is not computed yet, don't do
		// anything.
		if (swipeTransition._currentScene != toScene \|\| distance == DistanceUnspecified) {
		return fromScene to 0f
		}

		// If the offset is past the distance then let's change fromScene so that the user can swipe
		// to the next screen or go back to the previous one.
		val offset = swipeTransition.dragOffset
		val absoluteDistance = distance.absoluteValue
		return if (offset <= -absoluteDistance && swipes.upOrLeftResult?.toScene == toScene.key) {
		toScene to absoluteDistance
		} else if (offset >= absoluteDistance && swipes.downOrRightResult?.toScene == toScene.key) {
		toScene to -absoluteDistance
		} else {
		fromScene to 0f
		}
		}

		override fun onStop(velocity: Float, canChangeScene: Boolean): Float {
		// The state was changed since the drag started; don't do anything.
		if (!isDrivingTransition \|\| swipeTransition.isFinishing) {
		@@ -604,11 +606,14 @@ private class SwipeTransition(
		// subscribes to the offset value.
		val offset = offsetAnimation?.animatable?.value ?: dragOffset

		return computeProgress(offset)
		}

		fun computeProgress(offset: Float): Float {
		val distance = distance()
		if (distance == DistanceUnspecified) {
		return 0f
		}

		return offset / distance
		}

		@@ -707,18 +712,19 @@ private class SwipeTransition(
		targetOffset: Float,
		targetScene: SceneKey,
		): OffsetAnimation {
		val initialProgress = progress
		// Skip the animation if we have already reached the target scene and the overscroll does
		// not animate anything.
		val hasReachedTargetScene =
		(targetScene == toScene && progress >= 1f) \|\|
		(targetScene == fromScene && progress <= 0f)
		val skipAnimation = hasReachedTargetScene && !canOverscroll()
		(targetScene == toScene && initialProgress >= 1f) \|\|
		(targetScene == fromScene && initialProgress <= 0f)
		val skipAnimation = hasReachedTargetScene && !isWithinProgressRange(initialProgress)

		return startOffsetAnimation {
		val animatable = Animatable(dragOffset, OffsetVisibilityThreshold)
		val isTargetGreater = targetOffset > animatable.value
		val startedWhenOvercrollingTargetScene =
		if (targetScene == fromScene) progress < 0f else progress > 1f
		if (targetScene == fromScene) initialProgress < 0f else initialProgress > 1f
		val job =
		coroutineScope
		// Important: We start atomically to make sure that we start the coroutine even
		@@ -765,7 +771,7 @@ private class SwipeTransition(

		// Immediately stop this transition if we are bouncing on a
		// scene that does not bounce.
		if (!canOverscroll()) {
		if (!isWithinProgressRange(progress)) {
		snapToScene(targetScene)
		}
		}

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

+12 −3

Original line number	Diff line number	Diff line
		@@ -234,9 +234,18 @@ sealed interface TransitionState {
		}

		/** Returns if the [progress] value of this transition can go beyond range `[0; 1]` */
		fun canOverscroll(): Boolean {
		val overscrollSpec = currentOverscrollSpec ?: return true
		return overscrollSpec.transformationSpec.transformations.isNotEmpty()
		internal fun isWithinProgressRange(progress: Float): Boolean {
		// If the properties are missing we assume that every [Transition] can overscroll
		if (this !is HasOverscrollProperties) return true
		// [OverscrollSpec] for the current scene, even if it hasn't started overscrolling yet.
		val specForCurrentScene =
		when {
		progress <= 0f -> fromOverscrollSpec
		progress >= 1f -> toOverscrollSpec
		else -> null
		} ?: return true

		return specForCurrentScene.transformationSpec.transformations.isNotEmpty()
		}

		/**