STL dispatches events using the Nested Scroll system (8ab73c30) · Commits · e / os / android_frameworks_base

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

+136 −31

Original line number	Diff line number	Diff line
		@@ -16,12 +16,16 @@

		package com.android.compose.animation.scene

		import androidx.annotation.VisibleForTesting
		import androidx.compose.foundation.gestures.Orientation
		import androidx.compose.foundation.gestures.awaitHorizontalTouchSlopOrCancellation
		import androidx.compose.foundation.gestures.awaitVerticalTouchSlopOrCancellation
		import androidx.compose.runtime.Stable
		import androidx.compose.ui.Modifier
		import androidx.compose.ui.geometry.Offset
		import androidx.compose.ui.input.nestedscroll.NestedScrollConnection
		import androidx.compose.ui.input.nestedscroll.NestedScrollDispatcher
		import androidx.compose.ui.input.nestedscroll.NestedScrollSource
		import androidx.compose.ui.input.pointer.AwaitPointerEventScope
		import androidx.compose.ui.input.pointer.PointerEvent
		import androidx.compose.ui.input.pointer.PointerEventPass
		@@ -36,13 +40,11 @@ import androidx.compose.ui.input.pointer.positionChangeIgnoreConsumed
		import androidx.compose.ui.input.pointer.util.VelocityTracker
		import androidx.compose.ui.input.pointer.util.addPointerInputChange
		import androidx.compose.ui.node.CompositionLocalConsumerModifierNode
		import androidx.compose.ui.node.DelegatableNode
		import androidx.compose.ui.node.DelegatingNode
		import androidx.compose.ui.node.ModifierNodeElement
		import androidx.compose.ui.node.ObserverModifierNode
		import androidx.compose.ui.node.PointerInputModifierNode
		import androidx.compose.ui.node.currentValueOf
		import androidx.compose.ui.node.findNearestAncestor
		import androidx.compose.ui.node.observeReads
		import androidx.compose.ui.platform.LocalViewConfiguration
		import androidx.compose.ui.unit.IntSize
		@@ -51,6 +53,7 @@ import androidx.compose.ui.util.fastAll
		import androidx.compose.ui.util.fastAny
		import androidx.compose.ui.util.fastFirstOrNull
		import androidx.compose.ui.util.fastSumBy
		import com.android.compose.ui.util.SpaceVectorConverter
		import kotlin.coroutines.cancellation.CancellationException
		import kotlin.math.sign
		import kotlinx.coroutines.coroutineScope
		@@ -71,6 +74,7 @@ import kotlinx.coroutines.launch
		* dragged) and a second pointer is down and dragged. This is an implementation detail that might
		* change in the future.
		*/
		@VisibleForTesting
		@Stable
		internal fun Modifier.multiPointerDraggable(
		orientation: Orientation,
		@@ -78,6 +82,7 @@ internal fun Modifier.multiPointerDraggable(
		startDragImmediately: (startedPosition: Offset) -> Boolean,
		onDragStarted: (startedPosition: Offset, overSlop: Float, pointersDown: Int) -> DragController,
		swipeDetector: SwipeDetector = DefaultSwipeDetector,
		dispatcher: NestedScrollDispatcher,
		): Modifier =
		this.then(
		MultiPointerDraggableElement(
		@@ -86,6 +91,7 @@ internal fun Modifier.multiPointerDraggable(
		startDragImmediately,
		onDragStarted,
		swipeDetector,
		dispatcher,
		)
		)

		@@ -96,6 +102,7 @@ private data class MultiPointerDraggableElement(
		private val onDragStarted:
		(startedPosition: Offset, overSlop: Float, pointersDown: Int) -> DragController,
		private val swipeDetector: SwipeDetector,
		private val dispatcher: NestedScrollDispatcher,
		) : ModifierNodeElement<MultiPointerDraggableNode>() {
		override fun create(): MultiPointerDraggableNode =
		MultiPointerDraggableNode(
		@@ -104,6 +111,7 @@ private data class MultiPointerDraggableElement(
		startDragImmediately = startDragImmediately,
		onDragStarted = onDragStarted,
		swipeDetector = swipeDetector,
		dispatcher = dispatcher,
		)

		override fun update(node: MultiPointerDraggableNode) {
		@@ -122,11 +130,13 @@ internal class MultiPointerDraggableNode(
		var onDragStarted:
		(startedPosition: Offset, overSlop: Float, pointersDown: Int) -> DragController,
		var swipeDetector: SwipeDetector = DefaultSwipeDetector,
		private val dispatcher: NestedScrollDispatcher,
		) :
		DelegatingNode(),
		PointerInputModifierNode,
		CompositionLocalConsumerModifierNode,
		ObserverModifierNode {
		ObserverModifierNode,
		SpaceVectorConverter {
		private val pointerInputHandler: suspend PointerInputScope.() -> Unit = { pointerInput() }
		private val delegate = delegate(SuspendingPointerInputModifierNode(pointerInputHandler))
		private val velocityTracker = VelocityTracker()
		@@ -141,26 +151,22 @@ internal class MultiPointerDraggableNode(
		}
		}

		private var _toFloat = orientation.toFunctionOffsetToFloat()
		private var converter = SpaceVectorConverter(orientation)

		private fun Offset.toFloat(): Float = _toFloat(this)
		override fun Offset.toFloat(): Float = with(converter) { this@toFloat.toFloat() }

		private fun Orientation.toFunctionOffsetToFloat(): (Offset) -> Float =
		when (this) {
		Orientation.Vertical -> {
		{ it.y }
		}
		Orientation.Horizontal -> {
		{ it.x }
		}
		}
		override fun Velocity.toFloat(): Float = with(converter) { this@toFloat.toFloat() }

		override fun Float.toOffset(): Offset = with(converter) { this@toOffset.toOffset() }

		override fun Float.toVelocity(): Velocity = with(converter) { this@toVelocity.toVelocity() }

		var orientation: Orientation = orientation
		set(value) {
		// Reset the pointer input whenever orientation changed.
		if (value != field) {
		field = value
		_toFloat = field.toFunctionOffsetToFloat()
		converter = SpaceVectorConverter(value)
		delegate.resetPointerInputHandler()
		}
		}
		@@ -240,28 +246,32 @@ internal class MultiPointerDraggableNode(
		},
		onDrag = { controller, change, amount ->
		velocityTracker.addPointerInputChange(change)
		controller.onDrag(amount)
		dispatchScrollEvents(
		availableOnPreScroll = amount,
		onScroll = { controller.onDrag(it) },
		source = NestedScrollSource.UserInput,
		)
		},
		onDragEnd = { controller ->
		val viewConfiguration = currentValueOf(LocalViewConfiguration)
		val maxVelocity =
		viewConfiguration.maximumFlingVelocity.let {
		Velocity(it, it)
		}
		val velocity = velocityTracker.calculateVelocity(maxVelocity)
		controller.onStop(
		velocity =
		when (orientation) {
		Orientation.Horizontal -> velocity.x
		Orientation.Vertical -> velocity.y
		},
		canChangeScene = true,
		startFlingGesture(
		initialVelocity =
		currentValueOf(LocalViewConfiguration)
		.maximumFlingVelocity
		.let {
		val maxVelocity = Velocity(it, it)
		velocityTracker.calculateVelocity(maxVelocity)
		}
		.toFloat(),
		onFling = { controller.onStop(it, canChangeScene = true) }
		)
		},
		onDragCancel = { controller ->
		controller.onStop(velocity = 0f, canChangeScene = true)
		startFlingGesture(
		initialVelocity = 0f,
		onFling = { controller.onStop(it, canChangeScene = true) }
		)
		},
		swipeDetector = swipeDetector
		swipeDetector = swipeDetector,
		)
		} catch (exception: CancellationException) {
		// If the coroutine scope is active, we can just restart the drag cycle.
		@@ -275,6 +285,101 @@ internal class MultiPointerDraggableNode(
		}
		}

		/**
		* Start a fling gesture in another CoroutineScope, this is to ensure that even when the pointer
		* input scope is reset we will continue any coroutine scope that we started from these methods
		* while the pointer input scope was active.
		*
		* Note: Inspired by [androidx.compose.foundation.gestures.ScrollableNode.onDragStopped]
		*/
		private fun startFlingGesture(initialVelocity: Float, onFling: (velocity: Float) -> Float) {
		// Note: [AwaitPointerEventScope] is annotated as @RestrictsSuspension, we need another
		// CoroutineScope to run the fling gestures.
		// We do not need to cancel this [Job], the source will take care of emitting an
		// [onPostFling] before starting a new gesture.
		dispatcher.coroutineScope.launch {
		dispatchFlingEvents(availableOnPreFling = initialVelocity, onFling = onFling)
		}
		}

		/**
		* Use the nested scroll system to fire scroll events. This allows us to consume events from our
		* ancestors during the pre-scroll and post-scroll phases.
		*
		* @param availableOnPreScroll amount available before the scroll, this can be partially
		* consumed by our ancestors.
		* @param onScroll function that returns the amount consumed during a scroll given the amount
		* available after the [NestedScrollConnection.onPreScroll].
		* @param source the source of the scroll event
		* @return Total offset consumed.
		*/
		private inline fun dispatchScrollEvents(
		availableOnPreScroll: Float,
		onScroll: (delta: Float) -> Float,
		source: NestedScrollSource,
		): Float {
		// PreScroll phase
		val consumedByPreScroll =
		dispatcher
		.dispatchPreScroll(
		available = availableOnPreScroll.toOffset(),
		source = source,
		)
		.toFloat()

		// Scroll phase
		val availableOnScroll = availableOnPreScroll - consumedByPreScroll
		val consumedBySelfScroll = onScroll(availableOnScroll)

		// PostScroll phase
		val availableOnPostScroll = availableOnScroll - consumedBySelfScroll
		val consumedByPostScroll =
		dispatcher
		.dispatchPostScroll(
		consumed = consumedBySelfScroll.toOffset(),
		available = availableOnPostScroll.toOffset(),
		source = source,
		)
		.toFloat()

		return consumedByPreScroll + consumedBySelfScroll + consumedByPostScroll
		}

		/**
		* Use the nested scroll system to fire fling events. This allows us to consume events from our
		* ancestors during the pre-fling and post-fling phases.
		*
		* @param availableOnPreFling velocity available before the fling, this can be partially
		* consumed by our ancestors.
		* @param onFling function that returns the velocity consumed during the fling given the
		* velocity available after the [NestedScrollConnection.onPreFling].
		* @return Total velocity consumed.
		*/
		private suspend inline fun dispatchFlingEvents(
		availableOnPreFling: Float,
		onFling: (velocity: Float) -> Float,
		): Float {
		// PreFling phase
		val consumedByPreFling =
		dispatcher.dispatchPreFling(available = availableOnPreFling.toVelocity()).toFloat()

		// Fling phase
		val availableOnFling = availableOnPreFling - consumedByPreFling
		val consumedBySelfFling = onFling(availableOnFling)

		// PostFling phase
		val availableOnPostFling = availableOnFling - consumedBySelfFling
		val consumedByPostFling =
		dispatcher
		.dispatchPostFling(
		consumed = consumedBySelfFling.toVelocity(),
		available = availableOnPostFling.toVelocity(),
		)
		.toFloat()

		return consumedByPreFling + consumedBySelfFling + consumedByPostFling
		}

		/**
		* Detect drag gestures in the given [orientation].
		*

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

+4 −1

Original line number	Diff line number	Diff line
		@@ -20,6 +20,7 @@ import androidx.compose.foundation.gestures.Orientation
		import androidx.compose.runtime.Stable
		import androidx.compose.ui.Modifier
		import androidx.compose.ui.geometry.Offset
		import androidx.compose.ui.input.nestedscroll.NestedScrollDispatcher
		import androidx.compose.ui.input.nestedscroll.nestedScrollModifierNode
		import androidx.compose.ui.input.pointer.PointerEvent
		import androidx.compose.ui.input.pointer.PointerEventPass
		@@ -57,6 +58,7 @@ private class SwipeToSceneNode(
		draggableHandler: DraggableHandlerImpl,
		swipeDetector: SwipeDetector,
		) : DelegatingNode(), PointerInputModifierNode {
		private val dispatcher = NestedScrollDispatcher()
		private val multiPointerDraggableNode =
		delegate(
		MultiPointerDraggableNode(
		@@ -65,6 +67,7 @@ private class SwipeToSceneNode(
		startDragImmediately = ::startDragImmediately,
		onDragStarted = draggableHandler::onDragStarted,
		swipeDetector = swipeDetector,
		dispatcher = dispatcher,
		)
		)

		@@ -93,7 +96,7 @@ private class SwipeToSceneNode(
		)

		init {
		delegate(nestedScrollModifierNode(nestedScrollHandlerImpl.connection, dispatcher = null))
		delegate(nestedScrollModifierNode(nestedScrollHandlerImpl.connection, dispatcher))
		delegate(ScrollBehaviorOwnerNode(draggableHandler.nestedScrollKey, nestedScrollHandlerImpl))
		}

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

+136 −4

Original line number	Diff line number	Diff line
		@@ -28,6 +28,10 @@ import androidx.compose.runtime.setValue
		import androidx.compose.ui.Modifier
		import androidx.compose.ui.geometry.Offset
		import androidx.compose.ui.geometry.Size
		import androidx.compose.ui.input.nestedscroll.NestedScrollConnection
		import androidx.compose.ui.input.nestedscroll.NestedScrollDispatcher
		import androidx.compose.ui.input.nestedscroll.NestedScrollSource
		import androidx.compose.ui.input.nestedscroll.nestedScroll
		import androidx.compose.ui.input.pointer.AwaitPointerEventScope
		import androidx.compose.ui.input.pointer.PointerEventPass
		import androidx.compose.ui.input.pointer.PointerInputChange
		@@ -37,6 +41,7 @@ import androidx.compose.ui.platform.LocalViewConfiguration
		import androidx.compose.ui.test.junit4.createComposeRule
		import androidx.compose.ui.test.onRoot
		import androidx.compose.ui.test.performTouchInput
		import androidx.compose.ui.unit.Velocity
		import androidx.test.ext.junit.runners.AndroidJUnit4
		import com.google.common.truth.Truth.assertThat
		import kotlinx.coroutines.coroutineScope
		@@ -49,17 +54,22 @@ import org.junit.runner.RunWith
		class MultiPointerDraggableTest {
		@get:Rule val rule = createComposeRule()

		private val emptyConnection = object : NestedScrollConnection {}
		private val defaultDispatcher = NestedScrollDispatcher()

		private fun Modifier.nestedScrollDispatcher() = nestedScroll(emptyConnection, defaultDispatcher)

		private class SimpleDragController(
		val onDrag: () -> Unit,
		val onStop: () -> Unit,
		val onDrag: (delta: Float) -> Unit,
		val onStop: (velocity: Float) -> Unit,
		) : DragController {
		override fun onDrag(delta: Float): Float {
		onDrag()
		onDrag.invoke(delta)
		return delta
		}

		override fun onStop(velocity: Float, canChangeScene: Boolean): Float {
		onStop()
		onStop.invoke(velocity)
		return velocity
		}
		}
		@@ -79,6 +89,7 @@ class MultiPointerDraggableTest {
		touchSlop = LocalViewConfiguration.current.touchSlop
		Box(
		Modifier.size(with(LocalDensity.current) { Size(size, size).toDpSize() })
		.nestedScrollDispatcher()
		.multiPointerDraggable(
		orientation = Orientation.Vertical,
		enabled = { enabled },
		@@ -90,6 +101,7 @@ class MultiPointerDraggableTest {
		onStop = { stopped = true },
		)
		},
		dispatcher = defaultDispatcher,
		)
		)
		}
		@@ -145,6 +157,7 @@ class MultiPointerDraggableTest {
		touchSlop = LocalViewConfiguration.current.touchSlop
		Box(
		Modifier.size(with(LocalDensity.current) { Size(size, size).toDpSize() })
		.nestedScrollDispatcher()
		.multiPointerDraggable(
		orientation = Orientation.Vertical,
		enabled = { true },
		@@ -157,6 +170,7 @@ class MultiPointerDraggableTest {
		onStop = { stopped = true },
		)
		},
		dispatcher = defaultDispatcher,
		)
		.pointerInput(Unit) {
		coroutineScope {
		@@ -217,6 +231,7 @@ class MultiPointerDraggableTest {
		touchSlop = LocalViewConfiguration.current.touchSlop
		Box(
		Modifier.size(with(LocalDensity.current) { Size(size, size).toDpSize() })
		.nestedScrollDispatcher()
		.multiPointerDraggable(
		orientation = Orientation.Vertical,
		enabled = { true },
		@@ -228,6 +243,7 @@ class MultiPointerDraggableTest {
		onStop = { stopped = true },
		)
		},
		dispatcher = defaultDispatcher,
		)
		) {
		if (hasScrollable) {
		@@ -335,6 +351,7 @@ class MultiPointerDraggableTest {
		touchSlop = LocalViewConfiguration.current.touchSlop
		Box(
		Modifier.size(with(LocalDensity.current) { Size(size, size).toDpSize() })
		.nestedScrollDispatcher()
		.multiPointerDraggable(
		orientation = Orientation.Vertical,
		enabled = { true },
		@@ -346,6 +363,7 @@ class MultiPointerDraggableTest {
		onStop = { stopped = true },
		)
		},
		dispatcher = defaultDispatcher,
		)
		) {
		Box(
		@@ -436,6 +454,7 @@ class MultiPointerDraggableTest {
		touchSlop = LocalViewConfiguration.current.touchSlop
		Box(
		Modifier.size(with(LocalDensity.current) { Size(size, size).toDpSize() })
		.nestedScrollDispatcher()
		.multiPointerDraggable(
		orientation = Orientation.Vertical,
		enabled = { true },
		@@ -447,6 +466,7 @@ class MultiPointerDraggableTest {
		onStop = { verticalStopped = true },
		)
		},
		dispatcher = defaultDispatcher,
		)
		.multiPointerDraggable(
		orientation = Orientation.Horizontal,
		@@ -459,6 +479,7 @@ class MultiPointerDraggableTest {
		onStop = { horizontalStopped = true },
		)
		},
		dispatcher = defaultDispatcher,
		)
		)
		}
		@@ -539,6 +560,7 @@ class MultiPointerDraggableTest {
		touchSlop = LocalViewConfiguration.current.touchSlop
		Box(
		Modifier.size(with(LocalDensity.current) { Size(size, size).toDpSize() })
		.nestedScrollDispatcher()
		.multiPointerDraggable(
		orientation = Orientation.Vertical,
		enabled = { true },
		@@ -557,6 +579,7 @@ class MultiPointerDraggableTest {
		onStop = { /* do nothing */ },
		)
		},
		dispatcher = defaultDispatcher,
		)
		) {}
		}
		@@ -587,4 +610,113 @@ class MultiPointerDraggableTest {

		assertThat(started).isTrue()
		}

		@Test
		fun multiPointerNestedScrollDispatcher() {
		val size = 200f
		val middle = Offset(size / 2f, size / 2f)
		var touchSlop = 0f

		var consumedOnPreScroll = 0f

		var availableOnPreScroll = Float.MIN_VALUE
		var availableOnPostScroll = Float.MIN_VALUE
		var availableOnPreFling = Float.MIN_VALUE
		var availableOnPostFling = Float.MIN_VALUE

		var consumedOnDrag = 0f
		var consumedOnDragStop = 0f

		val connection =
		object : NestedScrollConnection {
		override fun onPreScroll(available: Offset, source: NestedScrollSource): Offset {
		availableOnPreScroll = available.y
		return Offset(0f, consumedOnPreScroll)
		}

		override fun onPostScroll(
		consumed: Offset,
		available: Offset,
		source: NestedScrollSource
		): Offset {
		availableOnPostScroll = available.y
		return Offset.Zero
		}

		override suspend fun onPreFling(available: Velocity): Velocity {
		availableOnPreFling = available.y
		return Velocity.Zero
		}

		override suspend fun onPostFling(
		consumed: Velocity,
		available: Velocity
		): Velocity {
		availableOnPostFling = available.y
		return Velocity.Zero
		}
		}

		rule.setContent {
		touchSlop = LocalViewConfiguration.current.touchSlop
		Box(
		Modifier.size(with(LocalDensity.current) { Size(size, size).toDpSize() })
		.nestedScroll(connection)
		.nestedScrollDispatcher()
		.multiPointerDraggable(
		orientation = Orientation.Vertical,
		enabled = { true },
		startDragImmediately = { false },
		onDragStarted = { _, _, _ ->
		SimpleDragController(
		onDrag = { consumedOnDrag = it },
		onStop = { consumedOnDragStop = it },
		)
		},
		dispatcher = defaultDispatcher,
		)
		)
		}

		fun startDrag() {
		rule.onRoot().performTouchInput {
		down(middle)
		moveBy(Offset(0f, touchSlop))
		}
		}

		fun continueDrag() {
		rule.onRoot().performTouchInput { moveBy(Offset(0f, touchSlop)) }
		}

		fun stopDrag() {
		rule.onRoot().performTouchInput { up() }
		}

		startDrag()

		continueDrag()
		assertThat(availableOnPreScroll).isEqualTo(touchSlop)
		assertThat(consumedOnDrag).isEqualTo(touchSlop)
		assertThat(availableOnPostScroll).isEqualTo(0f)

		// Parent node consumes half of the gesture
		consumedOnPreScroll = touchSlop / 2f
		continueDrag()
		assertThat(availableOnPreScroll).isEqualTo(touchSlop)
		assertThat(consumedOnDrag).isEqualTo(touchSlop / 2f)
		assertThat(availableOnPostScroll).isEqualTo(0f)

		// Parent node consumes the gesture
		consumedOnPreScroll = touchSlop
		continueDrag()
		assertThat(availableOnPreScroll).isEqualTo(touchSlop)
		assertThat(consumedOnDrag).isEqualTo(0f)
		assertThat(availableOnPostScroll).isEqualTo(0f)

		// Parent node can intercept the velocity on stop
		stopDrag()
		assertThat(availableOnPreFling).isEqualTo(consumedOnDragStop)
		assertThat(availableOnPostFling).isEqualTo(0f)
		}
		}