Merge "Initialize Transition object children lazily" into androidx-main
diff --git a/compose/animation/animation-core/src/commonMain/kotlin/androidx/compose/animation/core/Transition.kt b/compose/animation/animation-core/src/commonMain/kotlin/androidx/compose/animation/core/Transition.kt
index 585c768..cf8436f 100644
--- a/compose/animation/animation-core/src/commonMain/kotlin/androidx/compose/animation/core/Transition.kt
+++ b/compose/animation/animation-core/src/commonMain/kotlin/androidx/compose/animation/core/Transition.kt
@@ -34,6 +34,7 @@
import androidx.compose.runtime.mutableStateListOf
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
import androidx.compose.runtime.setValue
import androidx.compose.runtime.snapshots.SnapshotStateObserver
import androidx.compose.runtime.withFrameNanos
@@ -52,6 +53,7 @@
import kotlin.math.roundToLong
import kotlinx.coroutines.CancellableContinuation
import kotlinx.coroutines.CancellationException
+import kotlinx.coroutines.CoroutineStart
import kotlinx.coroutines.coroutineScope
import kotlinx.coroutines.launch
import kotlinx.coroutines.suspendCancellableCoroutine
@@ -932,7 +934,7 @@
internal var startTimeNanos by mutableLongStateOf(AnimationConstants.UnspecifiedTime)
// This gets calculated every time child is updated/added
- internal var updateChildrenNeeded: Boolean by mutableStateOf(true)
+ private var updateChildrenNeeded: Boolean by mutableStateOf(false)
private val _animations = mutableStateListOf<TransitionAnimationState<*, *>>()
private val _transitions = mutableStateListOf<Transition<*>>()
@@ -1176,21 +1178,34 @@
internal fun animateTo(targetState: S) {
if (!isSeeking) {
updateTarget(targetState)
- // target != currentState adds LaunchedEffect into the tree in the same frame as
+ // target != currentState adds the effect into the tree in the same frame as
// target change.
if (targetState != currentState || isRunning || updateChildrenNeeded) {
- LaunchedEffect(this) {
- while (true) {
+ // We're using a composition-obtained scope + DisposableEffect here to give us
+ // control over coroutine dispatching
+ val coroutineScope = rememberCoroutineScope()
+ DisposableEffect(coroutineScope, this) {
+ // Launch the coroutine undispatched so the block is executed in the current
+ // frame. This is important as this initializes the state.
+ coroutineScope.launch(start = CoroutineStart.UNDISPATCHED) {
val durationScale = coroutineContext.durationScale
withFrameNanos {
- // This check is very important, as isSeeking may be changed off-band
- // between the last check in composition and this callback which
- // happens in the animation callback the next frame.
if (!isSeeking) {
onFrame(it / AnimationDebugDurationScale, durationScale)
}
}
+ while (isRunning) {
+ withFrameNanos {
+ // This check is very important, as isSeeking may be changed
+ // off-band between the last check in composition and this callback
+ // which happens in the animation callback the next frame.
+ if (!isSeeking) {
+ onFrame(it / AnimationDebugDurationScale, durationScale)
+ }
+ }
+ }
}
+ onDispose { }
}
}
}
