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Commit eb1be208 authored by Jordan Demeulenaere's avatar Jordan Demeulenaere
Browse files

Derive currentOverscrollSpec to avoid unnecessary layouts/placements 

Bug: 291071158
Test: atest ElementTest
Flag: com.android.systemui.scene_container
Change-Id: I6986ca06ed850be80c7be3aa70efbd14623d604f
parent 19719a16

packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/content/state/TransitionState.kt

+22 −10
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ import androidx.compose.animation.core.AnimationVector1D 
import androidx.compose.animation.core.spring

import androidx.compose.foundation.gestures.Orientation

import androidx.compose.runtime.Stable

import androidx.compose.runtime.State

import androidx.compose.runtime.derivedStateOf

import androidx.compose.runtime.getValue

import com.android.compose.animation.scene.ContentKey
@@ -249,18 +250,29 @@ sealed interface TransitionState { 
        private var fromOverscrollSpec: OverscrollSpecImpl? = null

        private var toOverscrollSpec: OverscrollSpecImpl? = null



        /** The current [OverscrollSpecImpl], if this transition is currently overscrolling. */

        internal val currentOverscrollSpec: OverscrollSpecImpl?

            get() {

                if (this !is HasOverscrollProperties) return null

        /**

         * The current [OverscrollSpecImpl], if this transition is currently overscrolling.

         *

         * Note: This is backed by a State<OverscrollSpecImpl?> because the overscroll spec is

         * derived from progress, and we don't want readers of currentOverscrollSpec to recompose

         * every time progress is changed.

         */

        private val _currentOverscrollSpec: State<OverscrollSpecImpl?>? =

            if (this !is HasOverscrollProperties) {

                null

            } else {

                derivedStateOf {

                    val progress = progress

                    val bouncingContent = bouncingContent

                return when {

                    when {

                        progress < 0f || bouncingContent == fromContent -> fromOverscrollSpec

                        progress > 1f || bouncingContent == toContent -> toOverscrollSpec

                        else -> null

                    }

                }

            }

        internal val currentOverscrollSpec: OverscrollSpecImpl?

            get() = _currentOverscrollSpec?.value



        /**

         * An animatable that animates from 1f to 0f. This will be used to nicely animate the sudden

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

+60 −0
Original line number Diff line number Diff line
@@ -46,6 +46,7 @@ import androidx.compose.ui.Alignment 
import androidx.compose.ui.Modifier

import androidx.compose.ui.geometry.Offset

import androidx.compose.ui.layout.approachLayout

import androidx.compose.ui.layout.layout

import androidx.compose.ui.platform.LocalViewConfiguration

import androidx.compose.ui.platform.testTag

import androidx.compose.ui.test.assertIsDisplayed
@@ -70,11 +71,13 @@ 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.content.state.TransitionState

import com.android.compose.animation.scene.subjects.assertThat

import com.android.compose.test.assertSizeIsEqualTo

import com.android.compose.test.setContentAndCreateMainScope

import com.android.compose.test.transition

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

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

import kotlinx.coroutines.CoroutineScope

import kotlinx.coroutines.launch

import org.junit.Assert.assertThrows
@@ -2580,4 +2583,61 @@ class ElementTest { 
            }

        }

    }



    @Test

    fun staticSharedElementShouldNotRemeasureOrReplaceDuringOverscrollableTransition() {

        val size = 30.dp

        var numberOfMeasurements = 0

        var numberOfPlacements = 0



        // Foo is a simple element that does not move or resize during the transition.

        @Composable

        fun SceneScope.Foo(modifier: Modifier = Modifier) {

            Box(

                modifier

                    .element(TestElements.Foo)

                    .layout { measurable, constraints ->

                        numberOfMeasurements++

                        measurable.measure(constraints).run {

                            numberOfPlacements++

                            layout(width, height) { place(0, 0) }

                        }

                    }

                    .size(size)

            )

        }



        val state = rule.runOnUiThread { MutableSceneTransitionLayoutState(SceneA) }

        val scope =

            rule.setContentAndCreateMainScope {

                SceneTransitionLayout(state) {

                    scene(SceneA) { Box(Modifier.fillMaxSize()) { Foo() } }

                    scene(SceneB) { Box(Modifier.fillMaxSize()) { Foo() } }

                }

            }



        // Start an overscrollable transition driven by progress.

        var progress by mutableFloatStateOf(0f)

        val transition = transition(from = SceneA, to = SceneB, progress = { progress })

        assertThat(transition).isInstanceOf(TransitionState.HasOverscrollProperties::class.java)

        scope.launch { state.startTransition(transition) }



        // Reset the counters after the first animation frame.

        rule.waitForIdle()

        numberOfMeasurements = 0

        numberOfPlacements = 0



        // Change the progress a bunch of times.

        val nFrames = 20

        repeat(nFrames) { i ->

            progress = i / nFrames.toFloat()

            rule.waitForIdle()



            // We shouldn't have remeasured or replaced Foo.

            assertWithMessage("Frame $i didn't remeasure Foo")

                .that(numberOfMeasurements)

                .isEqualTo(0)

            assertWithMessage("Frame $i didn't replace Foo").that(numberOfPlacements).isEqualTo(0)

        }

    }

}