Merge "Prepare a transition before starting it" into main (81b28b16) · Commits · e / os / android_frameworks_base

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

+9 −1

Original line number	Diff line number	Diff line
		@@ -356,6 +356,12 @@ internal class MutableSceneTransitionLayoutStateImpl(
		override suspend fun startTransition(transition: TransitionState.Transition, chain: Boolean) {
		checkThread()

		// Prepare the transition before starting it. This is outside of the try/finally block on
		// purpose because preparing a transition might throw an exception (e.g. if we find multiple
		// specs matching this transition), in which case we want to throw that exception here
		// before even starting the transition.
		prepareTransitionBeforeStarting(transition)

		try {
		// Start the transition.
		startTransitionInternal(transition, chain)
		@@ -367,7 +373,7 @@ internal class MutableSceneTransitionLayoutStateImpl(
		}
		}

		private fun startTransitionInternal(transition: TransitionState.Transition, chain: Boolean) {
		private fun prepareTransitionBeforeStarting(transition: TransitionState.Transition) {
		// Set the current scene and overlays on the transition.
		val currentState = transitionState
		transition.currentSceneWhenTransitionStarted = currentState.currentScene
		@@ -395,7 +401,9 @@ internal class MutableSceneTransitionLayoutStateImpl(
		} else {
		transition.updateOverscrollSpecs(fromSpec = null, toSpec = null)
		}
		}

		private fun startTransitionInternal(transition: TransitionState.Transition, chain: Boolean) {
		when (val currentState = transitionStates.last()) {
		is TransitionState.Idle -> {
		// Replace [Idle] by [transition].

+26 −0

Original line number	Diff line number	Diff line
		@@ -686,4 +686,30 @@ class SceneTransitionLayoutStateTest {
		assertThat(state.transitionState).isIdle()
		assertThat(job.isCancelled).isTrue()
		}

		@Test
		fun badTransitionSpecThrowsMeaningfulMessageWhenStartingTransition() {
		val state =
		MutableSceneTransitionLayoutState(
		SceneA,
		transitions {
		// This transition definition is bad because they both match when transitioning
		// from A to B.
		from(SceneA) {}
		to(SceneB) {}
		},
		)

		val exception =
		assertThrows(IllegalStateException::class.java) {
		runBlocking { state.startTransition(transition(from = SceneA, to = SceneB)) }
		}

		assertThat(exception)
		.hasMessageThat()
		.isEqualTo(
		"Found multiple transition specs for transition SceneKey(debugName=SceneA) => " +
		"SceneKey(debugName=SceneB)"
		)
		}
		}