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Commit 20f85cba authored by omarmt's avatar omarmt
Browse files

Improvements for stopping animations in SceneGestureHandler 

The following improvements have been made:
- on onDragStarted(): When a new transition begins, the current
animation is stopped and the current drag offset is immediately obtained.
- New log: If the transition is a generic TransitionState.Transition, a
log is added, since it is not fully supported at the moment.
- on onDragStopped(): An animation has been added when the animation is
stopped when the state is TransitionState.Transition.
- on animateOffset(): animateOffset no longer waits for the coroutine to
 complete to reset the isAnimatingOffset state.

Test: atest SceneGestureHandlerTest
Bug: 291025415
Change-Id: I3d04ea2a2c822a2b17b377046d43a31757dcbd19
parent 08a4f97f

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

+50 −34
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 


package com.android.compose.animation.scene



import android.util.Log

import androidx.annotation.VisibleForTesting

import androidx.compose.animation.core.Animatable

import androidx.compose.animation.core.Spring
@@ -130,10 +131,12 @@ class SceneGestureHandler( 
    internal val currentScene: Scene

        get() = layoutImpl.scene(transitionState.currentScene)



    internal val isDrivingTransition

    @VisibleForTesting

    val isDrivingTransition

        get() = transitionState == swipeTransition



    internal var isAnimatingOffset

    @VisibleForTesting

    var isAnimatingOffset

        get() = swipeTransition.isAnimatingOffset

        private set(value) {

            swipeTransition.isAnimatingOffset = value
@@ -157,17 +160,21 @@ class SceneGestureHandler( 
    internal fun onDragStarted() {

        if (isDrivingTransition) {

            // This [transition] was already driving the animation: simply take over it.

            if (isAnimatingOffset) {

                // Stop animating and start from where the current offset. Setting the animation job

                // to `null` will effectively cancel the animation.

            // Stop animating and start from where the current offset.

            swipeTransition.stopOffsetAnimation()

                swipeTransition.dragOffset = swipeTransition.offsetAnimatable.value

            }



            return

        }



        val transition = transitionState

        if (transition is TransitionState.Transition) {

            // TODO(b/290184746): Better handle interruptions here if state != idle.

            Log.w(

                TAG,

                "start from TransitionState.Transition is not fully supported: from" +

                    " ${transition.fromScene} to ${transition.toScene} " +

                    "(progress ${transition.progress})"

            )

        }



        val fromScene = currentScene
@@ -409,8 +416,7 @@ class SceneGestureHandler( 
        targetScene: SceneKey,

    ) {

        swipeTransition.startOffsetAnimation {

            coroutineScope

                .launch {

            coroutineScope.launch {

                if (!isAnimatingOffset) {

                    swipeTransition.offsetAnimatable.snapTo(swipeTransition.dragOffset)

                }
@@ -426,15 +432,16 @@ class SceneGestureHandler( 
                    initialVelocity = initialVelocity,

                )



                    // Now that the animation is done, the state should be idle. Note that if the

                    // state was changed since this animation started, some external code changed it

                    // and we shouldn't do anything here. Note also that this job will be cancelled

                    // in the case where the user intercepts this swipe.

                isAnimatingOffset = false



                // Now that the animation is done, the state should be idle. Note that if the state

                // was changed since this animation started, some external code changed it and we

                // shouldn't do anything here. Note also that this job will be cancelled in the case

                // where the user intercepts this swipe.

                if (isDrivingTransition) {

                    transitionState = TransitionState.Idle(targetScene)

                }

            }

                .also { it.invokeOnCompletion { isAnimatingOffset = false } }

        }

    }
@@ -490,6 +497,11 @@ class SceneGestureHandler( 
        /** Stops any ongoing offset animation. */

        fun stopOffsetAnimation() {

            offsetAnimationJob?.cancel()



            if (isAnimatingOffset) {

                isAnimatingOffset = false

                dragOffset = offsetAnimatable.value

            }

        }



        /** The absolute distance between [fromScene] and [toScene]. */
@@ -503,6 +515,10 @@ class SceneGestureHandler( 
        val distance: Float

            get() = _distance

    }



    companion object {

        private const val TAG = "SceneGestureHandler"

    }

}



private class SceneDraggableHandler(

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

+32 −1
Original line number Diff line number Diff line
@@ -47,7 +47,7 @@ class SceneGestureHandlerTest { 
            scene(SceneC) { Text("SceneC") }

        }



        private val sceneGestureHandler =

        val sceneGestureHandler =

            SceneGestureHandler(

                layoutImpl =

                    SceneTransitionLayoutImpl(
@@ -81,6 +81,10 @@ class SceneGestureHandlerTest { 
            coroutineScope.testScheduler.advanceUntilIdle()

        }



        fun runCurrent() {

            coroutineScope.testScheduler.runCurrent()

        }



        fun assertScene(currentScene: SceneKey, isIdle: Boolean) {

            val idleMsg = if (isIdle) "MUST" else "MUST NOT"

            assertWithMessage("transitionState $idleMsg be Idle")
@@ -164,6 +168,33 @@ class SceneGestureHandlerTest { 
        assertScene(currentScene = SceneA, isIdle = true)

    }



    @Test

    fun startGestureDuringAnimatingOffset_shouldImmediatelyStopTheAnimation() = runGestureTest {

        draggable.onDragStarted(coroutineScope = coroutineScope, startedPosition = Offset.Zero)

        assertScene(currentScene = SceneA, isIdle = false)



        draggable.onDelta(pixels = deltaInPixels10)

        assertScene(currentScene = SceneA, isIdle = false)



        draggable.onDragStopped(

            coroutineScope = coroutineScope,

            velocity = velocityThreshold,

        )



        // The stop animation is not started yet

        assertThat(sceneGestureHandler.isAnimatingOffset).isFalse()



        runCurrent()



        assertThat(sceneGestureHandler.isAnimatingOffset).isTrue()

        assertThat(sceneGestureHandler.isDrivingTransition).isTrue()

        assertScene(currentScene = SceneC, isIdle = false)



        // Start a new gesture while the offset is animating

        draggable.onDragStarted(coroutineScope = coroutineScope, startedPosition = Offset.Zero)

        assertThat(sceneGestureHandler.isAnimatingOffset).isFalse()

    }



    @Test

    fun onInitialPreScroll_doNotChangeState() = runGestureTest {

        nestedScroll.onPreScroll(available = offsetY10, source = NestedScrollSource.Drag)