Don't seek stack animation transition on back start when predictive b…

…ack animatable is specified
arkivanov · Oct 14, 2024 · 72a0187 · 72a0187
1 parent 674b14f
commit 72a0187
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Showing 2 changed files with 76 additions and 9 deletions.
diff --git a/...ivanov/decompose/extensions/compose/experimental/stack/animation/DefaultStackAnimation.kt b/...ivanov/decompose/extensions/compose/experimental/stack/animation/DefaultStackAnimation.kt
@@ -264,7 +264,7 @@ internal class DefaultStackAnimation<C : Any, T : Any>(
             )
 
             scope.launch {
-                animationHandler.start(backEvent)
+                animationHandler.progress(backEvent)
             }
         }
 
@@ -301,14 +301,6 @@ internal class DefaultStackAnimation<C : Any, T : Any>(
         val exitTransitionState: SeekableTransitionState<EnterExitState> = SeekableTransitionState(EnterExitState.Visible)
         val enterTransitionState: SeekableTransitionState<EnterExitState> = SeekableTransitionState(EnterExitState.PreEnter)
 
-        suspend fun start(backEvent: BackEvent) {
-            awaitAll(
-                { exitTransitionState.seekTo(fraction = backEvent.progress, targetState = EnterExitState.PostExit) },
-                { enterTransitionState.seekTo(fraction = backEvent.progress, targetState = EnterExitState.Visible) },
-                { animatable?.animate(backEvent) },
-            )
-        }
-
         suspend fun progress(backEvent: BackEvent) {
             animatable?.run {
                 animate(backEvent)

diff --git a/...ov/decompose/extensions/compose/experimental/stack/animation/PredictiveBackGestureTest.kt b/...ov/decompose/extensions/compose/experimental/stack/animation/PredictiveBackGestureTest.kt
@@ -1,8 +1,13 @@
 package com.arkivanov.decompose.extensions.compose.experimental.stack.animation
 
 import androidx.compose.animation.EnterExitState
+import androidx.compose.animation.core.LinearEasing
+import androidx.compose.animation.core.Transition
 import androidx.compose.animation.core.animateFloat
+import androidx.compose.animation.core.tween
 import androidx.compose.material.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.State
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.setValue
@@ -408,6 +413,76 @@ class PredictiveBackGestureTest {
         assertFalse(values.any { it < 1F })
     }
 
+    @Test
+    fun GIVEN_predictive_animatable_not_null_and_two_children_in_stack_WHEN_gesture_progressed_THEN_animation_transition_not_animating() {
+        var stack by mutableStateOf(stack("1", "2"))
+
+        val animation =
+            DefaultStackAnimation(
+                predictiveBackAnimatable = ::TestAnimatable,
+                onBack = { stack = stack.dropLast() },
+            )
+
+        val values = HashMap<String, Float>()
+
+        composeRule.setContent {
+            animation(stack, Modifier) {
+                val value by transition.animateFloat()
+                values[it.configuration] = value
+            }
+        }
+
+        backDispatcher.startPredictiveBack(BackEvent(progress = 0.1F))
+        composeRule.waitForIdle()
+        backDispatcher.progressPredictiveBack(BackEvent(progress = 0.2F))
+        composeRule.waitForIdle()
+        backDispatcher.progressPredictiveBack(BackEvent(progress = 0.3F))
+        composeRule.waitForIdle()
+
+        assertEquals(0F, values["1"])
+        assertEquals(1F, values["2"])
+    }
+
+    @Test
+    fun GIVEN_predictive_animatable_null_and_two_children_in_stack_WHEN_gesture_progressed_THEN_animation_transition_animating() {
+        var stack by mutableStateOf(stack("1", "2"))
+
+        val animation =
+            DefaultStackAnimation(
+                predictiveBackAnimatable = { null },
+                onBack = { stack = stack.dropLast() },
+            )
+
+        val values = HashMap<String, Float>()
+
+        composeRule.setContent {
+            animation(stack, Modifier) {
+                val value by transition.animateFloat()
+                values[it.configuration] = value
+            }
+        }
+
+        backDispatcher.startPredictiveBack(BackEvent(progress = 0.1F))
+        composeRule.waitForIdle()
+        backDispatcher.progressPredictiveBack(BackEvent(progress = 0.2F))
+        composeRule.waitForIdle()
+        backDispatcher.progressPredictiveBack(BackEvent(progress = 0.3F))
+        composeRule.waitForIdle()
+
+        assertEquals(0.3F, values["1"])
+        assertEquals(0.7F, values["2"])
+    }
+
+    @Composable
+    private fun Transition<EnterExitState>.animateFloat(): State<Float> =
+        animateFloat(transitionSpec = { tween(easing = LinearEasing) }) { state ->
+            when (state) {
+                EnterExitState.PreEnter -> 0F
+                EnterExitState.Visible -> 1F
+                EnterExitState.PostExit -> 0F
+            }
+        }
+
     private fun DefaultStackAnimation(
         predictiveBackAnimatable: (initialBackEvent: BackEvent) -> PredictiveBackAnimatable? = ::TestAnimatable,
         onBack: () -> Unit,