Clip search view content during animation (#126975)

Fixes #126590

This PR is to clip the view content when the view size is not big enough, such as during animation.
Also removes some unused properties in `_ViewContent` class: `getRect` and `viewConstraints`

packages/flutter/lib/src/material/search_anchor.dart

@@ -579,11 +579,10 @@ class _SearchViewRoute extends PopupRoute<_SearchViewRoute> {
               viewHeaderTextStyle: viewHeaderTextStyle,
               viewHeaderHintStyle: viewHeaderHintStyle,
               dividerColor: dividerColor,
-              viewConstraints: viewConstraints,
               showFullScreenView: showFullScreenView,
               animation: curvedAnimation,
-              getRect: getRect,
               topPadding: topPadding,
+              viewMaxWidth: _rectTween.end!.width,
               viewRect: viewRect,
               viewDefaults: viewDefaults,
               viewTheme: viewTheme,
@@ -616,11 +615,10 @@ class _ViewContent extends StatefulWidget {
     this.viewHeaderTextStyle,
     this.viewHeaderHintStyle,
     this.dividerColor,
-    this.viewConstraints,
     required this.showFullScreenView,
-    required this.getRect,
     required this.topPadding,
     required this.animation,
+    required this.viewMaxWidth,
     required this.viewRect,
     required this.viewDefaults,
     required this.viewTheme,
@@ -641,11 +639,10 @@ class _ViewContent extends StatefulWidget {
   final TextStyle? viewHeaderTextStyle;
   final TextStyle? viewHeaderHintStyle;
   final Color? dividerColor;
-  final BoxConstraints? viewConstraints;
   final bool showFullScreenView;
-  final ValueGetter<Rect?> getRect;
   final double topPadding;
   final Animation<double> animation;
+  final double viewMaxWidth;
   final Rect viewRect;
   final SearchViewThemeData viewDefaults;
   final SearchViewThemeData viewTheme;
@@ -690,11 +687,13 @@ class _ViewContentState extends State<_ViewContent> {
     result = widget.suggestionsBuilder(context, _controller);
     final Size updatedScreenSize = MediaQuery.of(context).size;
 
-    if (_screenSize != updatedScreenSize && widget.showFullScreenView) {
+    if (_screenSize != updatedScreenSize) {
       _screenSize = updatedScreenSize;
+      if (widget.showFullScreenView) {
         _viewRect = Offset.zero & _screenSize!;
       }
     }
+  }
 
   Widget viewBuilder(Iterable<Widget> suggestions) {
     if (widget.viewBuilder == null) {
@@ -782,6 +781,12 @@ class _ViewContentState extends State<_ViewContent> {
             color: effectiveBackgroundColor,
             surfaceTintColor: effectiveSurfaceTint,
             elevation: effectiveElevation,
+            child: ClipRect(
+              clipBehavior: Clip.antiAlias,
+              child: OverflowBox(
+                alignment: Alignment.topLeft,
+                maxWidth: math.min(widget.viewMaxWidth, _screenSize!.width),
+                minWidth: 0,
                 child: FadeTransition(
                   opacity: CurvedAnimation(
                     parent: widget.animation,
@@ -837,6 +842,8 @@ class _ViewContentState extends State<_ViewContent> {
               ),
             ),
           ),
+        ),
+      ),
     );
   }
 }

packages/flutter/test/material/search_anchor_test.dart

@@ -1639,6 +1639,46 @@ void main() {
     await tester.pumpAndSettle();
     expect(find.byIcon(Icons.arrow_back), findsOneWidget);
   });
+
+  testWidgets('Search view route does not throw exception during pop animation', (WidgetTester tester) async {
+    // regression test for https://github.com/flutter/flutter/issues/126590.
+    await tester.pumpWidget(MaterialApp(
+      home: Material(
+        child: Center(
+          child: SearchAnchor(
+            builder: (BuildContext context, SearchController controller) {
+              return IconButton(
+                icon: const Icon(Icons.search),
+                onPressed: () {
+                  controller.openView();
+                },
+              );
+            },
+            suggestionsBuilder: (BuildContext context, SearchController controller) {
+              return List<Widget>.generate(5, (int index) {
+                final String item = 'item $index';
+                return ListTile(
+                  leading: const Icon(Icons.history),
+                  title: Text(item),
+                  trailing: const Icon(Icons.chevron_right),
+                  onTap: () {},
+                );
+              });
+            }),
+        ),
+      ),
+    ));
+
+    // Open search view
+    await tester.tap(find.byIcon(Icons.search));
+    await tester.pumpAndSettle();
+
+    // Pop search view route
+    await tester.tap(find.byIcon(Icons.arrow_back));
+    await tester.pumpAndSettle();
+
+    // No exception.
+  });
 }
 
 TextStyle? _iconStyle(WidgetTester tester, IconData icon) {