Merge "LargeTopAppBarNestedScrollConnection use PriorityNestedScrollConnection" into main (474c8834) · Commits · e / os / android_frameworks_base

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

+1 −0

Original line number	Diff line number	Diff line
		@@ -604,6 +604,7 @@ internal class SceneNestedScrollHandler(
		behavior.canStartOnPostFling && hasNextScene(velocityAvailable)
		},
		canContinueScroll = { true },
		canScrollOnFling = false,
		onStart = { offsetAvailable ->
		gestureHandler.gestureWithPriority = this
		gestureHandler.onDragStarted(

packages/SystemUI/compose/scene/src/com/android/compose/nestedscroll/LargeTopAppBarNestedScrollConnection.kt

+40 −56

Original line number	Diff line number	Diff line
		@@ -16,9 +16,8 @@

		package com.android.compose.nestedscroll

		import androidx.compose.ui.geometry.Offset
		import androidx.compose.foundation.gestures.Orientation
		import androidx.compose.ui.input.nestedscroll.NestedScrollConnection
		import androidx.compose.ui.input.nestedscroll.NestedScrollSource

		/**
		* A [NestedScrollConnection] that listens for all vertical scroll events and responds in the
		@@ -34,59 +33,44 @@ import androidx.compose.ui.input.nestedscroll.NestedScrollSource
		*
		* @sample com.android.compose.animation.scene.demo.Shade
		*/
		class LargeTopAppBarNestedScrollConnection(
		private val height: () -> Float,
		private val onChangeHeight: (Float) -> Unit,
		private val minHeight: Float,
		private val maxHeight: Float,
		) : NestedScrollConnection {

		constructor(
		fun LargeTopAppBarNestedScrollConnection(
		height: () -> Float,
		onHeightChanged: (Float) -> Unit,
		heightRange: ClosedFloatingPointRange<Float>,
		) : this(
		height = height,
		onChangeHeight = onHeightChanged,
		minHeight = heightRange.start,
		maxHeight = heightRange.endInclusive,
		)

		/**
		* When swiping up, the LargeTopAppBar will shrink (to [minHeight]) and the content will expand.
		* Then, you can then scroll down the content.
		*/
		override fun onPreScroll(available: Offset, source: NestedScrollSource): Offset {
		val y = available.y
		): PriorityNestedScrollConnection {
		val minHeight = heightRange.start
		val maxHeight = heightRange.endInclusive
		return PriorityNestedScrollConnection(
		orientation = Orientation.Vertical,
		// When swiping up, the LargeTopAppBar will shrink (to [minHeight]) and the content will
		// expand. Then, you can then scroll down the content.
		canStartPreScroll = { offsetAvailable, offsetBeforeStart ->
		offsetAvailable < 0 && offsetBeforeStart == 0f && height() > minHeight
		},
		// When swiping down, the content will scroll up until it reaches the top. Then, the
		// LargeTopAppBar will expand until it reaches its [maxHeight].
		canStartPostScroll = { offsetAvailable, _ -> offsetAvailable > 0 && height() < maxHeight },
		canStartPostFling = { false },
		canContinueScroll = {
		val currentHeight = height()
		if (y >= 0 \|\| currentHeight <= minHeight) {
		return Offset.Zero
		}

		val amountLeft = minHeight - currentHeight
		val amountConsumed = y.coerceAtLeast(amountLeft)
		onChangeHeight(currentHeight + amountConsumed)
		return Offset(0f, amountConsumed)
		}

		/**
		* When swiping down, the content will scroll up until it reaches the top. Then, the
		* LargeTopAppBar will expand until it reaches its [maxHeight].
		*/
		override fun onPostScroll(
		consumed: Offset,
		available: Offset,
		source: NestedScrollSource
		): Offset {
		val y = available.y
		minHeight < currentHeight && currentHeight < maxHeight
		},
		canScrollOnFling = true,
		onStart = { /* do nothing */},
		onScroll = { offsetAvailable ->
		val currentHeight = height()
		if (y <= 0 \|\| currentHeight >= maxHeight) {
		return Offset.Zero
		}

		val amountConsumed =
		if (offsetAvailable > 0) {
		val amountLeft = maxHeight - currentHeight
		val amountConsumed = y.coerceAtMost(amountLeft)
		onChangeHeight(currentHeight + amountConsumed)
		return Offset(0f, amountConsumed)
		offsetAvailable.coerceAtMost(amountLeft)
		} else {
		val amountLeft = minHeight - currentHeight
		offsetAvailable.coerceAtLeast(amountLeft)
		}
		onHeightChanged(currentHeight + amountConsumed)
		amountConsumed
		},
		// Don't consume the velocity on pre/post fling
		onStop = { 0f },
		)
		}

packages/SystemUI/compose/scene/src/com/android/compose/nestedscroll/PriorityNestedScrollConnection.kt

+13 −2

Original line number	Diff line number	Diff line
		@@ -38,6 +38,7 @@ class PriorityNestedScrollConnection(
		private val canStartPostScroll: (offsetAvailable: Offset, offsetBeforeStart: Offset) -> Boolean,
		private val canStartPostFling: (velocityAvailable: Velocity) -> Boolean,
		private val canContinueScroll: () -> Boolean,
		private val canScrollOnFling: Boolean,
		private val onStart: (offsetAvailable: Offset) -> Unit,
		private val onScroll: (offsetAvailable: Offset) -> Offset,
		private val onStop: (velocityAvailable: Velocity) -> Velocity,
		@@ -59,7 +60,7 @@ class PriorityNestedScrollConnection(

		if (
		isPriorityMode \|\|
		source == NestedScrollSource.Fling \|\|
		(source == NestedScrollSource.Fling && !canScrollOnFling) \|\|
		!canStartPostScroll(available, offsetBeforeStart)
		) {
		// The priority mode cannot start so we won't consume the available offset.
		@@ -71,7 +72,7 @@ class PriorityNestedScrollConnection(

		override fun onPreScroll(available: Offset, source: NestedScrollSource): Offset {
		if (!isPriorityMode) {
		if (source != NestedScrollSource.Fling) {
		if (source != NestedScrollSource.Fling \|\| canScrollOnFling) {
		if (canStartPreScroll(available, offsetScrolledBeforePriorityMode)) {
		return onPriorityStart(available)
		}
		@@ -98,12 +99,20 @@ class PriorityNestedScrollConnection(
		}

		override suspend fun onPreFling(available: Velocity): Velocity {
		if (isPriorityMode && canScrollOnFling) {
		// We don't want to consume the velocity, we prefer to continue receiving scroll events.
		return Velocity.Zero
		}
		// Step 3b: The finger is lifted, we can stop intercepting scroll events and use the speed
		// of the fling gesture.
		return onPriorityStop(velocity = available)
		}

		override suspend fun onPostFling(consumed: Velocity, available: Velocity): Velocity {
		if (isPriorityMode) {
		return onPriorityStop(velocity = available)
		}

		if (!canStartPostFling(available)) {
		return Velocity.Zero
		}
		@@ -156,6 +165,7 @@ fun PriorityNestedScrollConnection(
		canStartPostScroll: (offsetAvailable: Float, offsetBeforeStart: Float) -> Boolean,
		canStartPostFling: (velocityAvailable: Float) -> Boolean,
		canContinueScroll: () -> Boolean,
		canScrollOnFling: Boolean,
		onStart: (offsetAvailable: Float) -> Unit,
		onScroll: (offsetAvailable: Float) -> Float,
		onStop: (velocityAvailable: Float) -> Float,
		@@ -172,6 +182,7 @@ fun PriorityNestedScrollConnection(
		canStartPostFling(velocityAvailable.toFloat())
		},
		canContinueScroll = canContinueScroll,
		canScrollOnFling = canScrollOnFling,
		onStart = { offsetAvailable -> onStart(offsetAvailable.toFloat()) },
		onScroll = { offsetAvailable: Offset ->
		onScroll(offsetAvailable.toFloat()).toOffset()

packages/SystemUI/compose/scene/tests/src/com/android/compose/nestedscroll/LargeTopAppBarNestedScrollConnectionTest.kt

+66 −0

Original line number	Diff line number	Diff line
		@@ -17,6 +17,7 @@
		package com.android.compose.nestedscroll

		import androidx.compose.ui.geometry.Offset
		import androidx.compose.ui.input.nestedscroll.NestedScrollConnection
		import androidx.compose.ui.input.nestedscroll.NestedScrollSource
		import com.google.common.truth.Truth.assertThat
		import org.junit.Test
		@@ -36,6 +37,15 @@ class LargeTopAppBarNestedScrollConnectionTest(testCase: TestCase) {
		heightRange = heightRange,
		)

		private fun NestedScrollConnection.scroll(
		available: Offset,
		consumedByScroll: Offset = Offset.Zero,
		) {
		val consumedByPreScroll = onPreScroll(available = available, source = scrollSource)
		val consumed = consumedByPreScroll + consumedByScroll
		onPostScroll(consumed = consumed, available = available - consumed, source = scrollSource)
		}

		@Test
		fun onScrollUp_consumeHeightFirst() {
		val scrollConnection = buildScrollConnection(heightRange = 0f..2f)
		@@ -49,6 +59,41 @@ class LargeTopAppBarNestedScrollConnectionTest(testCase: TestCase) {
		assertThat(height).isEqualTo(0f)
		}

		@Test
		fun onScrollUpAfterContentScrolled_ignoreUpEvent() {
		val scrollConnection = buildScrollConnection(heightRange = 0f..2f)
		height = 1f

		// scroll down consumed by a child
		scrollConnection.scroll(available = Offset(0f, 1f), consumedByScroll = Offset(0f, 1f))

		val offsetConsumed =
		scrollConnection.onPreScroll(available = Offset(x = 0f, y = -1f), source = scrollSource)

		// It should ignore all onPreScroll events
		assertThat(offsetConsumed).isEqualTo(Offset.Zero)
		assertThat(height).isEqualTo(1f)
		}

		@Test
		fun onScrollUpAfterContentReturnedToZero_consumeHeight() {
		val scrollConnection = buildScrollConnection(heightRange = 0f..2f)
		height = 1f

		// scroll down consumed by a child
		scrollConnection.scroll(available = Offset(0f, 1f), consumedByScroll = Offset(0f, 1f))

		// scroll up consumed by a child, the child is in its original position
		scrollConnection.scroll(available = Offset(0f, -1f), consumedByScroll = Offset(0f, -1f))

		val offsetConsumed =
		scrollConnection.onPreScroll(available = Offset(x = 0f, y = -1f), source = scrollSource)

		// It should ignore all onPreScroll events
		assertThat(offsetConsumed).isEqualTo(Offset(0f, -1f))
		assertThat(height).isEqualTo(0f)
		}

		@Test
		fun onScrollUp_consumeDownToMin() {
		val scrollConnection = buildScrollConnection(heightRange = 0f..2f)
		@@ -109,6 +154,27 @@ class LargeTopAppBarNestedScrollConnectionTest(testCase: TestCase) {
		assertThat(height).isEqualTo(2f)
		}

		@Test
		fun onScrollDownAfterPostScroll_consumeHeightPreScroll() {
		val scrollConnection = buildScrollConnection(heightRange = 0f..2f)
		height = 1f
		scrollConnection.onPostScroll(
		consumed = Offset.Zero,
		available = Offset(x = 0f, y = 0.5f),
		source = scrollSource
		)

		val offsetConsumed =
		scrollConnection.onPreScroll(
		available = Offset(x = 0f, y = 0.5f),
		source = scrollSource
		)
		assertThat(offsetConsumed).isEqualTo(Offset(0f, 0.5f))

		// It can increase by 1 (0.5f + 0.5f) the height
		assertThat(height).isEqualTo(2f)
		}

		@Test
		fun onScrollDown_consumeUpToMax() {
		val scrollConnection = buildScrollConnection(heightRange = 0f..2f)

packages/SystemUI/compose/scene/tests/src/com/android/compose/nestedscroll/PriorityNestedScrollConnectionTest.kt

+1 −0

Original line number	Diff line number	Diff line
		@@ -46,6 +46,7 @@ class PriorityNestedScrollConnectionTest {
		canStartPostScroll = { _, _ -> canStartPostScroll },
		canStartPostFling = { canStartPostFling },
		canContinueScroll = { canContinueScroll },
		canScrollOnFling = false,
		onStart = { isStarted = true },
		onScroll = {
		lastScroll = it