Merge "Expose ElementKey.currentAlpha() in ContentScope" into main (96f6c51e) · Commits · e / os / android_frameworks_base

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

+2 −2

Original line number	Diff line number	Diff line
		@@ -692,7 +692,7 @@ internal class ElementNode(
		}

		/** The [TransitionState] that we should consider for [element]. */
		private fun elementState(
		internal fun elementState(
		layoutImpl: SceneTransitionLayoutImpl,
		element: Element,
		transitionStates: List<List<TransitionState>>,
		@@ -1127,7 +1127,7 @@ private fun isElementOpaque(
		* [isElementOpaque] is checked during placement and we don't want to read the transition progress
		* in that phase.
		*/
		private fun elementAlpha(
		internal fun elementAlpha(
		layoutImpl: SceneTransitionLayoutImpl,
		element: Element,
		transition: TransitionState.Transition?,

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

+9 −0

Original line number	Diff line number	Diff line
		@@ -312,6 +312,15 @@ interface BaseContentScope : ElementStateScope {
		fun Modifier.disableSwipesWhenScrolling(
		bounds: NestedScrollableBound = NestedScrollableBound.Any
		): Modifier

		/**
		* Return the alpha of [this] element in this content, given the current transition state and
		* transition transformations (e.g. fade).
		*
		* Important: This should not be read during composition and should instead be read during
		* layout, drawing or in a LaunchedEffect.
		*/
		fun ElementKey.currentAlpha(): Float?
		}

		@Stable

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

+14 −0

Original line number	Diff line number	Diff line
		@@ -76,8 +76,12 @@ import com.android.compose.animation.scene.UserAction
		import com.android.compose.animation.scene.UserActionResult
		import com.android.compose.animation.scene.ValueKey
		import com.android.compose.animation.scene.animateSharedValueAsState
		import com.android.compose.animation.scene.content.state.TransitionState
		import com.android.compose.animation.scene.effect.GestureEffect
		import com.android.compose.animation.scene.element
		import com.android.compose.animation.scene.elementAlpha
		import com.android.compose.animation.scene.elementState
		import com.android.compose.animation.scene.getAllNestedTransitionStates
		import com.android.compose.animation.scene.modifiers.noResizeDuringTransitions
		import com.android.compose.gesture.NestedScrollControlState
		import com.android.compose.gesture.NestedScrollableBound
		@@ -422,6 +426,16 @@ internal class ContentScopeImpl(
		it.fromContent == content \|\| it.toContent == content
		}
		}

		override fun ElementKey.currentAlpha(): Float? {
		val element = layoutImpl.elements[this] ?: return null
		val stateInContent = element.stateByContent[contentKey] ?: return null
		val elementState =
		elementState(layoutImpl, element, getAllNestedTransitionStates(layoutImpl))
		?: return null
		val transition = elementState as? TransitionState.Transition
		return elementAlpha(layoutImpl, element, transition, stateInContent)
		}
		}

		/** A [LifecycleOwner] that follows its [parentLifecycle] but is capped at [maxLifecycleState]. */

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

+53 −0

Original line number	Diff line number	Diff line
		@@ -24,11 +24,13 @@ import androidx.compose.foundation.layout.fillMaxSize
		import androidx.compose.runtime.Composable
		import androidx.compose.runtime.CompositionLocalProvider
		import androidx.compose.runtime.DisposableEffect
		import androidx.compose.runtime.LaunchedEffect
		import androidx.compose.runtime.SideEffect
		import androidx.compose.runtime.getValue
		import androidx.compose.runtime.mutableStateOf
		import androidx.compose.runtime.remember
		import androidx.compose.runtime.setValue
		import androidx.compose.runtime.snapshotFlow
		import androidx.compose.ui.Modifier
		import androidx.compose.ui.geometry.Offset
		import androidx.compose.ui.platform.LocalViewConfiguration
		@@ -380,4 +382,55 @@ class ContentTest {
		assertThat(nestedMiddle.ancestors).containsExactly(outerState)
		assertThat(nestedInner.ancestors).containsExactly(outerState, middleState).inOrder()
		}

		@Test
		fun currentElementAlpha() {
		var lastAlpha: Float? = null

		val state =
		rule.runOnUiThread {
		MutableSceneTransitionLayoutStateForTests(
		SceneA,
		transitions =
		transitions { from(SceneA, to = SceneB) { fade(TestElements.Foo) } },
		)
		}
		val scope =
		rule.setContentAndCreateMainScope {
		SceneTransitionLayout(state) {
		scene(SceneA) {}
		scene(SceneB) {
		LaunchedEffect(Unit) {
		snapshotFlow { TestElements.Foo.currentAlpha() }
		.collect { lastAlpha = it }
		}

		Box(Modifier.element(TestElements.Foo).fillMaxSize())
		}
		}
		}

		assertThat(lastAlpha).isNull()

		var progress by mutableStateOf(0f)
		scope.launch { state.startTransition(transition(SceneA, SceneB, progress = { progress })) }
		rule.waitForIdle()
		assertThat(lastAlpha).isWithin(0.01f).of(0f)

		progress = 0.25f
		rule.waitForIdle()
		assertThat(lastAlpha).isWithin(0.01f).of(0.25f)

		progress = 0.5f
		rule.waitForIdle()
		assertThat(lastAlpha).isWithin(0.01f).of(0.5f)

		progress = 0.75f
		rule.waitForIdle()
		assertThat(lastAlpha).isWithin(0.01f).of(0.75f)

		progress = 1f
		rule.waitForIdle()
		assertThat(lastAlpha).isWithin(0.01f).of(1f)
		}
		}