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Commit 2c02d345 authored by omarmt's avatar omarmt
Browse files

Introduction of the GestureHandler interface 

The GestureHandler interface allows us to simulate gesture events
(scroll and drag) generated by Compose. This is useful for testing the
behavior of our components, as we can verify that they are responding to
 gestures as expected.

Test: atest SceneGestureHandlerTest
Bug: 291025415
Change-Id: If8afda7f7ea02703cc6829c1a967a616dfa09859
parent fb0b1e0f

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

0 → 100644
+20 −0
Original line number Diff line number Diff line 
package com.android.compose.animation.scene



import androidx.compose.ui.geometry.Offset

import androidx.compose.ui.input.nestedscroll.NestedScrollConnection

import kotlinx.coroutines.CoroutineScope



interface GestureHandler {

    val draggable: DraggableHandler

    val nestedScroll: NestedScrollHandler

}



interface DraggableHandler {

    suspend fun onDragStarted(coroutineScope: CoroutineScope, startedPosition: Offset)

    fun onDelta(pixels: Float)

    suspend fun onDragStopped(coroutineScope: CoroutineScope, velocity: Float)

}



interface NestedScrollHandler {

    val connection: NestedScrollConnection

}

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

+17 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 


package com.android.compose.animation.scene



import androidx.compose.foundation.gestures.Orientation

import androidx.compose.foundation.layout.Box

import androidx.compose.runtime.Composable

import androidx.compose.runtime.State
@@ -100,3 +101,19 @@ private class SceneScopeImpl( 
        MovableElement(layoutImpl, scene, key, modifier, content)

    }

}



/** The destination scene when swiping up or left from [upOrLeft]. */

internal fun Scene.upOrLeft(orientation: Orientation): SceneKey? {

    return when (orientation) {

        Orientation.Vertical -> userActions[Swipe.Up]

        Orientation.Horizontal -> userActions[Swipe.Left]

    }

}



/** The destination scene when swiping down or right from [downOrRight]. */

internal fun Scene.downOrRight(orientation: Orientation): SceneKey? {

    return when (orientation) {

        Orientation.Vertical -> userActions[Swipe.Down]

        Orientation.Horizontal -> userActions[Swipe.Right]

    }

}

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

+4 −2
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
package com.android.compose.animation.scene



import androidx.activity.compose.BackHandler

import androidx.annotation.VisibleForTesting

import androidx.compose.foundation.gestures.Orientation

import androidx.compose.foundation.layout.Box

import androidx.compose.runtime.Composable
@@ -39,7 +40,8 @@ import androidx.compose.ui.unit.IntSize 
import com.android.compose.ui.util.fastForEach

import kotlinx.coroutines.channels.Channel



internal class SceneTransitionLayoutImpl(

@VisibleForTesting

class SceneTransitionLayoutImpl(

    onChangeScene: (SceneKey) -> Unit,

    builder: SceneTransitionLayoutScope.() -> Unit,

    transitions: SceneTransitions,
@@ -60,7 +62,7 @@ internal class SceneTransitionLayoutImpl( 
     * The size of this layout. Note that this could be [IntSize.Zero] if this layour does not have

     * any scene configured or right before the first measure pass of the layout.

     */

    internal var size by mutableStateOf(IntSize.Zero)

    @VisibleForTesting var size by mutableStateOf(IntSize.Zero)



    init {

        setScenes(builder)

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

+490 −528

File changed.

Preview size limit exceeded, changes collapsed.

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

0 → 100644
+284 −0
Original line number Diff line number Diff line 
package com.android.compose.animation.scene



import androidx.compose.foundation.gestures.Orientation

import androidx.compose.material3.Text

import androidx.compose.runtime.getValue

import androidx.compose.runtime.mutableStateOf

import androidx.compose.runtime.setValue

import androidx.compose.ui.geometry.Offset

import androidx.compose.ui.input.nestedscroll.NestedScrollSource

import androidx.compose.ui.test.ExperimentalTestApi

import androidx.compose.ui.unit.Density

import androidx.compose.ui.unit.IntSize

import androidx.compose.ui.unit.Velocity

import androidx.test.ext.junit.runners.AndroidJUnit4

import com.android.compose.animation.scene.TestScenes.SceneA

import com.android.compose.animation.scene.TestScenes.SceneB

import com.android.compose.animation.scene.TestScenes.SceneC

import com.android.compose.animation.scene.TransitionState.Idle

import com.android.compose.animation.scene.TransitionState.Transition

import com.android.compose.test.MonotonicClockTestScope

import com.android.compose.test.runMonotonicClockTest

import com.google.common.truth.Truth.assertThat

import com.google.common.truth.Truth.assertWithMessage

import org.junit.Test

import org.junit.runner.RunWith



private const val SCREEN_SIZE = 100f



@RunWith(AndroidJUnit4::class)

class SceneGestureHandlerTest {

    private class TestGestureScope(

        val coroutineScope: MonotonicClockTestScope,

    ) {

        private var internalCurrentScene: SceneKey by mutableStateOf(SceneA)



        private val layoutState: SceneTransitionLayoutState =

            SceneTransitionLayoutState(internalCurrentScene)



        private val scenesBuilder: SceneTransitionLayoutScope.() -> Unit = {

            scene(

                key = SceneA,

                userActions = mapOf(Swipe.Up to SceneB, Swipe.Down to SceneC),

            ) {

                Text("SceneA")

            }

            scene(SceneB) { Text("SceneB") }

            scene(SceneC) { Text("SceneC") }

        }



        private val sceneGestureHandler =

            SceneGestureHandler(

                layoutImpl =

                    SceneTransitionLayoutImpl(

                            onChangeScene = { internalCurrentScene = it },

                            builder = scenesBuilder,

                            transitions = EmptyTestTransitions,

                            state = layoutState,

                            density = Density(1f)

                        )

                        .also { it.size = IntSize(SCREEN_SIZE.toInt(), SCREEN_SIZE.toInt()) },

                orientation = Orientation.Vertical,

                coroutineScope = coroutineScope,

            )



        val draggable = sceneGestureHandler.draggable



        val nestedScroll = sceneGestureHandler.nestedScroll.connection



        val velocityThreshold = sceneGestureHandler.velocityThreshold



        // 10% of the screen

        val deltaInPixels10 = SCREEN_SIZE * 0.1f



        // Offset y: 10% of the screen

        val offsetY10 = Offset(x = 0f, y = deltaInPixels10)



        val transitionState: TransitionState

            get() = layoutState.transitionState



        fun advanceUntilIdle() {

            coroutineScope.testScheduler.advanceUntilIdle()

        }



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

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

            assertWithMessage("transitionState $idleMsg be Idle")

                .that(transitionState is Idle)

                .isEqualTo(isIdle)

            assertThat(transitionState.currentScene).isEqualTo(currentScene)

        }

    }



    @OptIn(ExperimentalTestApi::class)

    private fun runGestureTest(block: suspend TestGestureScope.() -> Unit) {

        runMonotonicClockTest { TestGestureScope(coroutineScope = this).block() }

    }



    @Test

    fun testPreconditions() = runGestureTest { assertScene(currentScene = SceneA, isIdle = true) }



    @Test

    fun onDragStarted_shouldStartATransition() = runGestureTest {

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

        assertScene(currentScene = SceneA, isIdle = false)

    }



    @Test

    fun afterSceneTransitionIsStarted_interceptDragEvents() = runGestureTest {

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

        assertScene(currentScene = SceneA, isIdle = false)

        val transition = transitionState as Transition



        draggable.onDelta(pixels = deltaInPixels10)

        assertThat(transition.progress).isEqualTo(0.1f)



        draggable.onDelta(pixels = deltaInPixels10)

        assertThat(transition.progress).isEqualTo(0.2f)

    }



    @Test

    fun onDragStoppedAfterDrag_velocityLowerThanThreshold_remainSameScene() = 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 - 0.01f,

        )

        assertScene(currentScene = SceneA, isIdle = false)



        // wait for the stop animation

        advanceUntilIdle()

        assertScene(currentScene = SceneA, isIdle = true)

    }



    @Test

    fun onDragStoppedAfterDrag_velocityAtLeastThreshold_goToNextScene() = 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,

        )

        assertScene(currentScene = SceneC, isIdle = false)



        // wait for the stop animation

        advanceUntilIdle()

        assertScene(currentScene = SceneC, isIdle = true)

    }



    @Test

    fun onDragStoppedAfterStarted_returnImmediatelyToIdle() = runGestureTest {

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

        assertScene(currentScene = SceneA, isIdle = false)



        draggable.onDragStopped(coroutineScope = coroutineScope, velocity = 0f)

        assertScene(currentScene = SceneA, isIdle = true)

    }



    @Test

    fun onInitialPreScroll_doNotChangeState() = runGestureTest {

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

        assertScene(currentScene = SceneA, isIdle = true)

    }



    @Test

    fun onPostScrollWithNothingAvailable_doNotChangeState() = runGestureTest {

        val consumed =

            nestedScroll.onPostScroll(

                consumed = Offset.Zero,

                available = Offset.Zero,

                source = NestedScrollSource.Drag

            )



        assertScene(currentScene = SceneA, isIdle = true)

        assertThat(consumed).isEqualTo(Offset.Zero)

    }



    @Test

    fun onPostScrollWithSomethingAvailable_startSceneTransition() = runGestureTest {

        val consumed =

            nestedScroll.onPostScroll(

                consumed = Offset.Zero,

                available = offsetY10,

                source = NestedScrollSource.Drag

            )



        assertScene(currentScene = SceneA, isIdle = false)

        val transition = transitionState as Transition

        assertThat(transition.progress).isEqualTo(0.1f)

        assertThat(consumed).isEqualTo(offsetY10)

    }



    private fun TestGestureScope.nestedScrollEvents(

        available: Offset,

        consumedByScroll: Offset = Offset.Zero,

    ) {

        val consumedByPreScroll =

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

        val consumed = consumedByPreScroll + consumedByScroll

        nestedScroll.onPostScroll(

            consumed = consumed,

            available = available - consumed,

            source = NestedScrollSource.Drag

        )

    }



    @Test

    fun afterSceneTransitionIsStarted_interceptPreScrollEvents() = runGestureTest {

        nestedScrollEvents(available = offsetY10)

        assertScene(currentScene = SceneA, isIdle = false)



        val transition = transitionState as Transition

        assertThat(transition.progress).isEqualTo(0.1f)



        // start intercept preScroll

        val consumed =

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

        assertThat(transition.progress).isEqualTo(0.2f)



        // do nothing on postScroll

        nestedScroll.onPostScroll(

            consumed = consumed,

            available = Offset.Zero,

            source = NestedScrollSource.Drag

        )

        assertThat(transition.progress).isEqualTo(0.2f)



        nestedScrollEvents(available = offsetY10)

        assertThat(transition.progress).isEqualTo(0.3f)

        assertScene(currentScene = SceneA, isIdle = false)

    }



    @Test

    fun onPreFling_velocityLowerThanThreshold_remainSameScene() = runGestureTest {

        nestedScrollEvents(available = offsetY10)

        assertScene(currentScene = SceneA, isIdle = false)



        nestedScroll.onPreFling(available = Velocity.Zero)

        assertScene(currentScene = SceneA, isIdle = false)



        // wait for the stop animation

        advanceUntilIdle()

        assertScene(currentScene = SceneA, isIdle = true)

    }



    @Test

    fun onPreFling_velocityAtLeastThreshold_goToNextScene() = runGestureTest {

        nestedScrollEvents(available = offsetY10)

        assertScene(currentScene = SceneA, isIdle = false)



        nestedScroll.onPreFling(available = Velocity(0f, velocityThreshold))

        assertScene(currentScene = SceneC, isIdle = false)



        // wait for the stop animation

        advanceUntilIdle()

        assertScene(currentScene = SceneC, isIdle = true)

    }



    @Test

    fun scrollStartedInScene_doOverscrollAnimation() = runGestureTest {

        // we started the scroll in the scene

        nestedScrollEvents(available = offsetY10, consumedByScroll = offsetY10)



        // now we can intercept the scroll events

        nestedScrollEvents(available = offsetY10)

        assertScene(currentScene = SceneA, isIdle = false)



        nestedScroll.onPreFling(available = Velocity(0f, velocityThreshold))

        // should start an overscroll animation (the gesture started in the scene)

        assertScene(currentScene = SceneA, isIdle = false)



        // wait for the stop animation

        advanceUntilIdle()

        assertScene(currentScene = SceneA, isIdle = true)

    }

}