[animations] Exposed clipBehavior for Opencontainer

AUTHORS

@@ -4,3 +4,4 @@
 #   Name/Organization <email address>
 
 Google Inc.
+Sarbagya Dhaubanjar <mail@sarbagyastha.com.np>

packages/animations/lib/src/open_container.dart

@@ -97,6 +97,7 @@ class OpenContainer<T extends Object> extends StatefulWidget {
     this.transitionDuration = const Duration(milliseconds: 300),
     this.transitionType = ContainerTransitionType.fade,
     this.useRootNavigator = false,
+    this.clipBehavior = Clip.antiAlias,
   })  : assert(closedColor != null),
         assert(openColor != null),
         assert(closedElevation != null),
@@ -108,6 +109,7 @@ class OpenContainer<T extends Object> extends StatefulWidget {
         assert(tappable != null),
         assert(transitionType != null),
         assert(useRootNavigator != null),
+        assert(clipBehavior != null),
         super(key: key);
 
   /// Background color of the container while it is closed.
@@ -257,6 +259,15 @@ class OpenContainer<T extends Object> extends StatefulWidget {
   /// to the nearest navigator.
   final bool useRootNavigator;
 
+  /// The [closedBuilder] will be clipped (or not) according to this option.
+  ///
+  /// Defaults to [Clip.antiAlias], and must not be null.
+  ///
+  /// See also:
+  ///
+  ///  * [Material.clipBehavior], which is used to implement this property.
+  final Clip clipBehavior;
+
   @override
   _OpenContainerState<T> createState() => _OpenContainerState<T>();
 }
@@ -308,7 +319,7 @@ class _OpenContainerState<T> extends State<OpenContainer<T>> {
       child: GestureDetector(
         onTap: widget.tappable ? openContainer : null,
         child: Material(
-          clipBehavior: Clip.antiAlias,
+          clipBehavior: widget.clipBehavior,
           color: widget.closedColor,
           elevation: widget.closedElevation,
           shape: widget.closedShape,

packages/animations/test/open_container_test.dart

@@ -1572,6 +1572,62 @@ void main() {
     expect(value, isTrue);
   });
 
+  testWidgets('closedBuilder has anti-alias clip by default',
+      (WidgetTester tester) async {
+    final GlobalKey closedBuilderKey = GlobalKey();
+    final Widget openContainer = OpenContainer(
+      closedBuilder: (BuildContext context, VoidCallback action) {
+        return Text('Close', key: closedBuilderKey);
+      },
+      openBuilder:
+          (BuildContext context, CloseContainerActionCallback<bool> action) {
+        return const Text('Open');
+      },
+    );
+
+    await tester.pumpWidget(
+      _boilerplate(child: openContainer),
+    );
+
+    final Finder closedBuilderMaterial = find
+        .ancestor(
+          of: find.byKey(closedBuilderKey),
+          matching: find.byType(Material),
+        )
+        .first;
+
+    final Material material = tester.widget<Material>(closedBuilderMaterial);
+    expect(material.clipBehavior, Clip.antiAlias);
+  });
+
+  testWidgets('closedBuilder has no clip', (WidgetTester tester) async {
+    final GlobalKey closedBuilderKey = GlobalKey();
+    final Widget openContainer = OpenContainer(
+      closedBuilder: (BuildContext context, VoidCallback action) {
+        return Text('Close', key: closedBuilderKey);
+      },
+      openBuilder:
+          (BuildContext context, CloseContainerActionCallback<bool> action) {
+        return const Text('Open');
+      },
+      clipBehavior: Clip.none,
+    );
+
+    await tester.pumpWidget(
+      _boilerplate(child: openContainer),
+    );
+
+    final Finder closedBuilderMaterial = find
+        .ancestor(
+          of: find.byKey(closedBuilderKey),
+          matching: find.byType(Material),
+        )
+        .first;
+
+    final Material material = tester.widget<Material>(closedBuilderMaterial);
+    expect(material.clipBehavior, Clip.none);
+  });
+
   Widget _createRootNavigatorTest({
     @required Key appKey,
     @required Key nestedNavigatorKey,