Move delegation logic to didChangeNext/didPopNext

flutter · MitchellGoodwin · Feb 15, 2024 · Feb 16, 2024 · Feb 20, 2024 · Mar 6, 2024
commit e5b686fefe6adfff847d5ddee96451b6b5da8ca8
diff --git a/packages/flutter/lib/src/cupertino/route.dart b/packages/flutter/lib/src/cupertino/route.dart
@@ -83,7 +83,7 @@ final Animatable<Offset> _kBottomUpTween = Tween<Offset>(
 ///  * [MaterialRouteTransitionMixin], which is a mixin that provides
 ///    platform-appropriate transitions for a [PageRoute].
 ///  * [CupertinoPageRoute], which is a [PageRoute] that leverages this mixin.
-mixin CupertinoRouteTransitionMixin<T> on PageRoute<T> implements FlexibleTransitionRouteMixin<T> {
+mixin CupertinoRouteTransitionMixin<T> on PageRoute<T> {
   /// Builds the primary contents of the route.
   @protected
   Widget buildContent(BuildContext context);
@@ -155,18 +155,12 @@ mixin CupertinoRouteTransitionMixin<T> on PageRoute<T> implements FlexibleTransi
     if (controller != null && controller!.isAnimating) {
       return false;
     }
-    if (nextRoute is FlexibleTransitionRouteMixin<T> && navigator != null) {
-      navigator!.delegateTransitionBuilder = (nextRoute as FlexibleTransitionRouteMixin<T>).delegatedTransition;
-    }
     // Don't perform outgoing animation if the next route is a fullscreen dialog.
     return nextRoute is FlexibleTransitionRouteMixin<T> || nextRoute is CupertinoRouteTransitionMixin && !nextRoute.fullscreenDialog;
   }
 
   @override
   bool canTransitionFrom(TransitionRoute<dynamic> previousRoute) {
-    if (previousRoute is FlexibleTransitionRouteMixin<T> && navigator != null && previousRoute.controller?.isAnimating != true) {
-      previousRoute.navigator!.delegateTransitionBuilder = delegatedTransition;
-    }
     return previousRoute is FlexibleTransitionRouteMixin<T> || previousRoute is CupertinoRouteTransitionMixin && !previousRoute.fullscreenDialog;
   }
 
@@ -286,7 +280,7 @@ mixin CupertinoRouteTransitionMixin<T> on PageRoute<T> implements FlexibleTransi
 ///  * [CupertinoTabScaffold], for applications that have a tab bar at the
 ///    bottom with multiple pages.
 ///  * [CupertinoPage], for a [Page] version of this class.
-class CupertinoPageRoute<T> extends PageRoute<T> with CupertinoRouteTransitionMixin<T> {
+class CupertinoPageRoute<T> extends PageRoute<T> with CupertinoRouteTransitionMixin<T>, FlexibleTransitionRouteMixin<T> {
   /// Creates a page route for use in an iOS designed app.
   ///
   /// The [builder], [maintainState], and [fullscreenDialog] arguments must not
@@ -326,7 +320,7 @@ class CupertinoPageRoute<T> extends PageRoute<T> with CupertinoRouteTransitionMi
 //
 // This route uses the builder from the page to build its content. This ensures
 // the content is up to date after page updates.
-class _PageBasedCupertinoPageRoute<T> extends PageRoute<T> with CupertinoRouteTransitionMixin<T> {
+class _PageBasedCupertinoPageRoute<T> extends PageRoute<T> with CupertinoRouteTransitionMixin<T>, FlexibleTransitionRouteMixin<T> {
   _PageBasedCupertinoPageRoute({
     required CupertinoPage<T> page,
     super.allowSnapshotting = true,

diff --git a/packages/flutter/lib/src/material/page.dart b/packages/flutter/lib/src/material/page.dart
@@ -32,7 +32,7 @@ import 'theme.dart';
 ///  * [MaterialRouteTransitionMixin], which provides the material transition
 ///    for this route.
 ///  * [MaterialPage], which is a [Page] of this class.
-class MaterialPageRoute<T> extends PageRoute<T> with MaterialRouteTransitionMixin<T> {
+class MaterialPageRoute<T> extends PageRoute<T> with MaterialRouteTransitionMixin<T>, FlexibleTransitionRouteMixin<T> {
   /// Construct a MaterialPageRoute whose contents are defined by [builder].
   MaterialPageRoute({
     required this.builder,
@@ -99,7 +99,6 @@ mixin MaterialRouteTransitionMixin<T> on PageRoute<T> implements FlexibleTransit
   @override
   DelegatedTransitionBuilder? get delegatedTransition => _delegatedTransition;
 
-  @override
   set delegatedTransition(DelegatedTransitionBuilder? newTransition) {
     _delegatedTransition = newTransition;
   }
@@ -109,20 +108,13 @@ mixin MaterialRouteTransitionMixin<T> on PageRoute<T> implements FlexibleTransit
     if (controller != null && controller!.isAnimating) {
       return false;
     }
-    if (nextRoute is FlexibleTransitionRouteMixin<T> && navigator != null) {
-      navigator!.delegateTransitionBuilder = (nextRoute as FlexibleTransitionRouteMixin<T>).delegatedTransition;
-    }
-    // Don't perform outgoing animation if the next route is a fullscreen dialog.
     return (nextRoute is MaterialRouteTransitionMixin && !nextRoute.fullscreenDialog)
       || (nextRoute is CupertinoRouteTransitionMixin && !nextRoute.fullscreenDialog)
       || (nextRoute is FlexibleTransitionRouteMixin<T>);
   }
 
   @override
   bool canTransitionFrom(TransitionRoute<dynamic> previousRoute) {
-    if (previousRoute is FlexibleTransitionRouteMixin<T> && navigator != null && previousRoute.controller?.isAnimating != true) {
-      previousRoute.navigator!.delegateTransitionBuilder = delegatedTransition;
-    }
     return previousRoute is PageRoute;
   }
 

diff --git a/packages/flutter/lib/src/widgets/routes.dart b/packages/flutter/lib/src/widgets/routes.dart
@@ -2489,7 +2489,24 @@ abstract class PopEntry<T> {
 
 /// Mixin for a route that can provide a delegated secondary transition to the
 /// outgoing route.
-abstract mixin class FlexibleTransitionRouteMixin<T> {
+mixin FlexibleTransitionRouteMixin<T> on TransitionRoute<T> {
   /// The delegated transition provided to the previous route.
-  late DelegatedTransitionBuilder? delegatedTransition;
+  DelegatedTransitionBuilder? get delegatedTransition;
+
+  @override
+  void didChangeNext(Route<dynamic>? nextRoute) {
+    if (nextRoute is FlexibleTransitionRouteMixin<T> && canTransitionTo(nextRoute) && navigator != null) {
+      debugPrint('Ping the navigator state');
+      navigator!.delegateTransitionBuilder = nextRoute.delegatedTransition;
+    }
+    super.didChangeNext(nextRoute);
+  }
+
+  @override
+  void didPopNext(Route<dynamic> nextRoute) {
+    if (nextRoute is FlexibleTransitionRouteMixin<T> && canTransitionTo(nextRoute) && navigator != null) {
+      navigator!.delegateTransitionBuilder = nextRoute.delegatedTransition;
+    }
+    super.didPopNext(nextRoute);
+  }
 }