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Commit a972b5f5 authored by omarmt's avatar omarmt
Browse files

The animation between scenes can only be intercepted in a defined range 

A transition between scenes can only be intercepted by a scrollable
component if the animation progress is within a certain range. In this
CL, the progress must be between 5% and 95% to be intercepted during
preScroll.

Test: atest SceneGestureHandlerTest
Bug: 291053278
Flag: NA
Change-Id: Id998095286e67da7bfdecf729e59d9afafcd3700
parent fdca966c

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

+26 −6
Original line number Diff line number Diff line
@@ -38,13 +38,13 @@ import kotlinx.coroutines.launch 


@VisibleForTesting

class SceneGestureHandler(

    private val layoutImpl: SceneTransitionLayoutImpl,

    internal val layoutImpl: SceneTransitionLayoutImpl,

    internal val orientation: Orientation,

    private val coroutineScope: CoroutineScope,

) {

    val draggable: DraggableHandler = SceneDraggableHandler(this)



    private var transitionState

    internal var transitionState

        get() = layoutImpl.state.transitionState

        set(value) {

            layoutImpl.state.transitionState = value
@@ -57,7 +57,7 @@ class SceneGestureHandler( 
     * Note: the initialScene here does not matter, it's only used for initializing the transition

     * and will be replaced when a drag event starts.

     */

    private val swipeTransition = SwipeTransition(initialScene = currentScene)

    internal val swipeTransition = SwipeTransition(initialScene = currentScene)



    internal val currentScene: Scene

        get() = layoutImpl.scene(transitionState.currentScene)
@@ -414,7 +414,7 @@ class SceneGestureHandler( 
        }

    }



    private class SwipeTransition(initialScene: Scene) : TransitionState.Transition {

    internal class SwipeTransition(initialScene: Scene) : TransitionState.Transition {

        var _currentScene by mutableStateOf(initialScene)

        override val currentScene: SceneKey

            get() = _currentScene.key
@@ -597,9 +597,29 @@ class SceneNestedScrollHandler( 
        return PriorityNestedScrollConnection(

            canStartPreScroll = { offsetAvailable, offsetBeforeStart ->

                canChangeScene = offsetBeforeStart == Offset.Zero

                gestureHandler.isDrivingTransition &&



                val canInterceptSwipeTransition =

                    canChangeScene &&

                        gestureHandler.isDrivingTransition &&

                        offsetAvailable.toAmount() != 0f

                if (!canInterceptSwipeTransition) return@PriorityNestedScrollConnection false



                val progress = gestureHandler.swipeTransition.progress

                val threshold = gestureHandler.layoutImpl.transitionInterceptionThreshold

                fun isProgressCloseTo(value: Float) = (progress - value).absoluteValue <= threshold



                // The transition is always between 0 and 1. If it is close to either of these

                // intervals, we want to go directly to the TransitionState.Idle.

                // The progress value can go beyond this range in the case of overscroll.

                val shouldSnapToIdle = isProgressCloseTo(0f) || isProgressCloseTo(1f)

                if (shouldSnapToIdle) {

                    gestureHandler.swipeTransition.stopOffsetAnimation()

                    gestureHandler.transitionState =

                        TransitionState.Idle(gestureHandler.swipeTransition.currentScene)

                }



                // Start only if we cannot consume this event

                !shouldSnapToIdle

            },

            canStartPostScroll = { offsetAvailable, offsetBeforeStart ->

                val amount = offsetAvailable.toAmount()

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

+6 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 


package com.android.compose.animation.scene



import androidx.annotation.FloatRange

import androidx.compose.foundation.gestures.Orientation

import androidx.compose.runtime.Composable

import androidx.compose.runtime.State
@@ -41,6 +42,8 @@ import androidx.compose.ui.platform.LocalDensity 
 * @param transitions the definition of the transitions used to animate a change of scene.

 * @param state the observable state of this layout.

 * @param edgeDetector the edge detector used to detect which edge a swipe is started from, if any.

 * @param transitionInterceptionThreshold used during a scene transition. For the scene to be

 *   intercepted, the progress value must be above the threshold, and below (1 - threshold).

 * @param scenes the configuration of the different scenes of this layout.

 */

@Composable
@@ -51,6 +54,7 @@ fun SceneTransitionLayout( 
    modifier: Modifier = Modifier,

    state: SceneTransitionLayoutState = remember { SceneTransitionLayoutState(currentScene) },

    edgeDetector: EdgeDetector = DefaultEdgeDetector,

    @FloatRange(from = 0.0, to = 0.5) transitionInterceptionThreshold: Float = 0f,

    scenes: SceneTransitionLayoutScope.() -> Unit,

) {

    val density = LocalDensity.current
@@ -63,6 +67,7 @@ fun SceneTransitionLayout( 
            state = state,

            density = density,

            edgeDetector = edgeDetector,

            transitionInterceptionThreshold = transitionInterceptionThreshold,

            coroutineScope = coroutineScope,

        )

    }
@@ -71,6 +76,7 @@ fun SceneTransitionLayout( 
    layoutImpl.transitions = transitions

    layoutImpl.density = density

    layoutImpl.edgeDetector = edgeDetector

    layoutImpl.transitionInterceptionThreshold = transitionInterceptionThreshold



    layoutImpl.setScenes(scenes)

    layoutImpl.setCurrentScene(currentScene)

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

+2 −0
Original line number Diff line number Diff line
@@ -48,6 +48,7 @@ class SceneTransitionLayoutImpl( 
    internal val state: SceneTransitionLayoutState,

    density: Density,

    edgeDetector: EdgeDetector,

    transitionInterceptionThreshold: Float,

    coroutineScope: CoroutineScope,

) {

    internal val scenes = SnapshotStateMap<SceneKey, Scene>()
@@ -60,6 +61,7 @@ class SceneTransitionLayoutImpl( 
    internal var transitions by mutableStateOf(transitions)

    internal var density: Density by mutableStateOf(density)

    internal var edgeDetector by mutableStateOf(edgeDetector)

    internal var transitionInterceptionThreshold by mutableStateOf(transitionInterceptionThreshold)



    private val horizontalGestureHandler: SceneGestureHandler

    private val verticalGestureHandler: SceneGestureHandler

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

+62 −0
Original line number Diff line number Diff line
@@ -68,6 +68,8 @@ class SceneGestureHandlerTest { 
            scene(SceneC) { Text("SceneC") }

        }



        val transitionInterceptionThreshold = 0.05f



        val sceneGestureHandler =

            SceneGestureHandler(

                layoutImpl =
@@ -78,6 +80,7 @@ class SceneGestureHandlerTest { 
                            state = layoutState,

                            density = Density(1f),

                            edgeDetector = DefaultEdgeDetector,

                            transitionInterceptionThreshold = transitionInterceptionThreshold,

                            coroutineScope = coroutineScope,

                        )

                        .also { it.size = IntSize(SCREEN_SIZE.toInt(), SCREEN_SIZE.toInt()) },
@@ -299,6 +302,64 @@ class SceneGestureHandlerTest { 
        assertScene(currentScene = SceneA, isIdle = false)

    }



    private suspend fun TestGestureScope.preScrollAfterSceneTransition(

        firstScroll: Float,

        secondScroll: Float

    ) {

        val nestedScroll = nestedScrollConnection(nestedScrollBehavior = EdgeWithOverscroll)

        // start scene transition

        nestedScroll.scroll(available = Offset(0f, SCREEN_SIZE * firstScroll))



        // stop scene transition (start the "stop animation")

        nestedScroll.onPreFling(available = Velocity.Zero)



        // a pre scroll event, that could be intercepted by SceneGestureHandler

        nestedScroll.onPreScroll(Offset(0f, SCREEN_SIZE * secondScroll), NestedScrollSource.Drag)

    }



    // Float tolerance for comparisons

    private val tolerance = 0.00001f



    @Test

    fun scrollAndFling_scrollLessThanInterceptable_goToIdleOnCurrentScene() = runGestureTest {

        val first = transitionInterceptionThreshold - tolerance

        val second = 0.01f



        preScrollAfterSceneTransition(firstScroll = first, secondScroll = second)



        assertScene(SceneA, isIdle = true)

    }



    @Test

    fun scrollAndFling_scrollMinInterceptable_interceptPreScrollEvents() = runGestureTest {

        val first = transitionInterceptionThreshold + tolerance

        val second = 0.01f



        preScrollAfterSceneTransition(firstScroll = first, secondScroll = second)



        assertThat((transitionState as Transition).progress).isWithin(tolerance).of(first + second)

    }



    @Test

    fun scrollAndFling_scrollMaxInterceptable_interceptPreScrollEvents() = runGestureTest {

        val first = 1f - transitionInterceptionThreshold - tolerance

        val second = 0.01f



        preScrollAfterSceneTransition(firstScroll = first, secondScroll = second)



        assertThat((transitionState as Transition).progress).isWithin(tolerance).of(first + second)

    }



    @Test

    fun scrollAndFling_scrollMoreThanInterceptable_goToIdleOnNextScene() = runGestureTest {

        val first = 1f - transitionInterceptionThreshold + tolerance

        val second = 0.01f



        preScrollAfterSceneTransition(firstScroll = first, secondScroll = second)



        assertScene(SceneC, isIdle = true)

    }



    @Test

    fun onPreFling_velocityLowerThanThreshold_remainSameScene() = runGestureTest {

        val nestedScroll = nestedScrollConnection(nestedScrollBehavior = EdgeWithOverscroll)
@@ -421,6 +482,7 @@ class SceneGestureHandlerTest { 
        draggable.onDelta(deltaInPixels10)

        assertScene(currentScene = SceneA, isIdle = true)

    }



    @Test

    fun beforeDraggableStart_stop_shouldBeIgnored() = runGestureTest {

        draggable.onDragStopped(velocityThreshold)