Per screen transition experimental api (#424)

* Per Screen transition experimental API * Update transitionSpec to avoid behavior change * fix lint * update api dump
adrielcafe · May 21, 2024 · 764388a · 764388a
1 parent 309e6c7
commit 764388a
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diff --git a/voyager-transitions/api/android/voyager-transitions.api b/voyager-transitions/api/android/voyager-transitions.api
@@ -47,6 +47,11 @@ public final class cafe/adriel/voyager/transitions/ScaleTransitionKt {
 	public static final fun ScaleTransition (Lcafe/adriel/voyager/navigator/Navigator;Landroidx/compose/ui/Modifier;Landroidx/compose/animation/core/FiniteAnimationSpec;Lkotlin/jvm/functions/Function4;Landroidx/compose/runtime/Composer;II)V
 }
 
+public final class cafe/adriel/voyager/transitions/ScreenTransition$DefaultImpls {
+	public static fun enter (Lcafe/adriel/voyager/transitions/ScreenTransition;)Landroidx/compose/animation/EnterTransition;
+	public static fun exit (Lcafe/adriel/voyager/transitions/ScreenTransition;)Landroidx/compose/animation/ExitTransition;
+}
+
 public final class cafe/adriel/voyager/transitions/ScreenTransitionKt {
 	public static final fun ScreenTransition (Lcafe/adriel/voyager/navigator/Navigator;Lkotlin/jvm/functions/Function1;Landroidx/compose/ui/Modifier;Lkotlin/jvm/functions/Function4;Landroidx/compose/runtime/Composer;II)V
 	public static final fun ScreenTransition (Lcafe/adriel/voyager/navigator/Navigator;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Landroidx/compose/ui/Modifier;Lkotlin/jvm/functions/Function4;Landroidx/compose/runtime/Composer;II)V

diff --git a/voyager-transitions/api/desktop/voyager-transitions.api b/voyager-transitions/api/desktop/voyager-transitions.api
@@ -47,6 +47,11 @@ public final class cafe/adriel/voyager/transitions/ScaleTransitionKt {
 	public static final fun ScaleTransition (Lcafe/adriel/voyager/navigator/Navigator;Landroidx/compose/ui/Modifier;Landroidx/compose/animation/core/FiniteAnimationSpec;Lkotlin/jvm/functions/Function4;Landroidx/compose/runtime/Composer;II)V
 }
 
+public final class cafe/adriel/voyager/transitions/ScreenTransition$DefaultImpls {
+	public static fun enter (Lcafe/adriel/voyager/transitions/ScreenTransition;)Landroidx/compose/animation/EnterTransition;
+	public static fun exit (Lcafe/adriel/voyager/transitions/ScreenTransition;)Landroidx/compose/animation/ExitTransition;
+}
+
 public final class cafe/adriel/voyager/transitions/ScreenTransitionKt {
 	public static final fun ScreenTransition (Lcafe/adriel/voyager/navigator/Navigator;Lkotlin/jvm/functions/Function1;Landroidx/compose/ui/Modifier;Lkotlin/jvm/functions/Function4;Landroidx/compose/runtime/Composer;II)V
 	public static final fun ScreenTransition (Lcafe/adriel/voyager/navigator/Navigator;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;Landroidx/compose/ui/Modifier;Lkotlin/jvm/functions/Function4;Landroidx/compose/runtime/Composer;II)V

diff --git a/...ger-transitions/src/commonMain/kotlin/cafe/adriel/voyager/transitions/ScreenTransition.kt b/...ger-transitions/src/commonMain/kotlin/cafe/adriel/voyager/transitions/ScreenTransition.kt
@@ -4,12 +4,34 @@ import androidx.compose.animation.AnimatedContent
 import androidx.compose.animation.AnimatedContentTransitionScope
 import androidx.compose.animation.AnimatedVisibilityScope
 import androidx.compose.animation.ContentTransform
+import androidx.compose.animation.EnterTransition
+import androidx.compose.animation.ExitTransition
+import androidx.compose.animation.togetherWith
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
+import cafe.adriel.voyager.core.annotation.ExperimentalVoyagerApi
 import cafe.adriel.voyager.core.screen.Screen
 import cafe.adriel.voyager.core.stack.StackEvent
 import cafe.adriel.voyager.navigator.Navigator
 
+@ExperimentalVoyagerApi
+public interface ScreenTransition {
+
+    /**
+     * Defines the enter transition for the Screen.
+     *
+     * Returns null when it should not define a transition for this screen.
+     */
+    public fun enter(): EnterTransition? = null
+
+    /**
+     * Defines the exit transition for the Screen.
+     *
+     * Returns null when it should not define a transition for this screen.
+     */
+    public fun exit(): ExitTransition? = null
+}
+
 public typealias ScreenTransitionContent = @Composable AnimatedVisibilityScope.(Screen) -> Unit
 
 @Composable
@@ -42,7 +64,30 @@ public fun ScreenTransition(
 ) {
     AnimatedContent(
         targetState = navigator.lastItem,
-        transitionSpec = transition,
+        transitionSpec = {
+            val contentTransform = transition()
+
+            val isPop = navigator.lastEvent == StackEvent.Pop
+
+            val screenEnterTransition = if (isPop) {
+                (targetState as? ScreenTransition)?.enter()
+            } else {
+                (targetState as? ScreenTransition)?.enter()
+            }
+
+            val screenExitTransition = if (isPop) {
+                (initialState as? ScreenTransition)?.exit()
+            } else {
+                (initialState as? ScreenTransition)?.exit()
+            }
+
+            if (screenExitTransition != null || screenEnterTransition != null) {
+                (screenEnterTransition ?: contentTransform.targetContentEnter) togetherWith
+                    (screenExitTransition ?: contentTransform.initialContentExit)
+            } else {
+                contentTransform
+            }
+        },
         modifier = modifier
     ) { screen ->
         navigator.saveableState("transition", screen) {