Fix drawers are draggable on desktop platforms (#100476)

Author: TahaTesser

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

@@ -565,6 +565,19 @@ class DrawerControllerState extends State<DrawerController> with SingleTickerPro
     final bool drawerIsStart = widget.alignment == DrawerAlignment.start;
     final EdgeInsets padding = MediaQuery.of(context).padding;
     final TextDirection textDirection = Directionality.of(context);
+    final bool isDesktop;
+    switch (Theme.of(context).platform) {
+      case TargetPlatform.android:
+      case TargetPlatform.iOS:
+      case TargetPlatform.fuchsia:
+        isDesktop = false;
+        break;
+      case TargetPlatform.macOS:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
+        isDesktop = true;
+        break;
+    }
 
     double? dragAreaWidth = widget.edgeDragWidth;
     if (widget.edgeDragWidth == null) {
@@ -581,7 +594,7 @@ class DrawerControllerState extends State<DrawerController> with SingleTickerPro
     }
 
     if (_controller.status == AnimationStatus.dismissed) {
-      if (widget.enableOpenDragGesture) {
+      if (widget.enableOpenDragGesture && !isDesktop) {
         return Align(
           alignment: _drawerOuterAlignment,
           child: GestureDetector(
@@ -612,52 +625,57 @@ class DrawerControllerState extends State<DrawerController> with SingleTickerPro
           break;
       }
       assert(platformHasBackButton != null);
-      return GestureDetector(
-        key: _gestureDetectorKey,
-        onHorizontalDragDown: _handleDragDown,
-        onHorizontalDragUpdate: _move,
-        onHorizontalDragEnd: _settle,
-        onHorizontalDragCancel: _handleDragCancel,
-        excludeFromSemantics: true,
-        dragStartBehavior: widget.dragStartBehavior,
-        child: RepaintBoundary(
-          child: Stack(
-            children: <Widget>[
-              BlockSemantics(
-                child: ExcludeSemantics(
-                  // On Android, the back button is used to dismiss a modal.
-                  excluding: platformHasBackButton,
-                  child: GestureDetector(
-                    onTap: close,
-                    child: Semantics(
-                      label: MaterialLocalizations.of(context).modalBarrierDismissLabel,
-                      child: MouseRegion(
-                        child: Container( // The drawer's "scrim"
-                          color: _scrimColorTween.evaluate(_controller),
-                        ),
-                      ),
+
+      final Widget child =  RepaintBoundary(
+        child: Stack(
+          children: <Widget>[
+            BlockSemantics(
+              child: ExcludeSemantics(
+                // On Android, the back button is used to dismiss a modal.
+                excluding: platformHasBackButton,
+                child: GestureDetector(
+                  onTap: close,
+                  child: Semantics(
+                    label: MaterialLocalizations.of(context).modalBarrierDismissLabel,
+                    child: Container( // The drawer's "scrim"
+                      color: _scrimColorTween.evaluate(_controller),
                     ),
                   ),
                 ),
               ),
-              Align(
-                alignment: _drawerOuterAlignment,
-                child: Align(
-                  alignment: _drawerInnerAlignment,
-                  widthFactor: _controller.value,
-                  child: RepaintBoundary(
-                    child: FocusScope(
-                      key: _drawerKey,
-                      node: _focusScopeNode,
-                      child: widget.child,
-                    ),
+            ),
+            Align(
+              alignment: _drawerOuterAlignment,
+              child: Align(
+                alignment: _drawerInnerAlignment,
+                widthFactor: _controller.value,
+                child: RepaintBoundary(
+                  child: FocusScope(
+                    key: _drawerKey,
+                    node: _focusScopeNode,
+                    child: widget.child,
                   ),
                 ),
               ),
-            ],
-          ),
+            ),
+          ],
         ),
       );
+
+      if (isDesktop) {
+        return child;
+      }
+
+      return GestureDetector(
+        key: _gestureDetectorKey,
+        onHorizontalDragDown: _handleDragDown,
+        onHorizontalDragUpdate: _move,
+        onHorizontalDragEnd: _settle,
+        onHorizontalDragCancel: _handleDragCancel,
+        excludeFromSemantics: true,
+        dragStartBehavior: widget.dragStartBehavior,
+        child: child,
+      );
     }
   }
 

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

@@ -1617,7 +1617,7 @@ class Scaffold extends StatefulWidget {
   /// [Navigator.pop].
   ///
   /// {@tool dartpad}
-  /// To disable the drawer edge swipe, set the
+  /// To disable the drawer edge swipe on mobile, set the
   /// [Scaffold.drawerEnableOpenDragGesture] to false. Then, use
   /// [ScaffoldState.openDrawer] to open the drawer and [Navigator.pop] to close
   /// it.
@@ -1739,15 +1739,19 @@ class Scaffold extends StatefulWidget {
   final double? drawerEdgeDragWidth;
 
   /// Determines if the [Scaffold.drawer] can be opened with a drag
-  /// gesture.
+  /// gesture on mobile.
+  ///
+  /// On desktop platforms, the drawer is not draggable.
   ///
-  /// By default, the drag gesture is enabled.
+  /// By default, the drag gesture is enabled on mobile.
   final bool drawerEnableOpenDragGesture;
 
   /// Determines if the [Scaffold.endDrawer] can be opened with a
-  /// drag gesture.
+  /// gesture on mobile.
+  ///
+  /// On desktop platforms, the drawer is not draggable.
   ///
-  /// By default, the drag gesture is enabled.
+  /// By default, the drag gesture is enabled on mobile.
   final bool endDrawerEnableOpenDragGesture;
 
   /// Restoration ID to save and restore the state of the [Scaffold].

packages/flutter/test/material/scaffold_test.dart

@@ -1777,7 +1777,7 @@ void main() {
     expect(scaffoldState.isDrawerOpen, true);
   });
 
-  testWidgets('Drawer does not open with a drag gesture when it is disabled', (WidgetTester tester) async {
+  testWidgets('Drawer does not open with a drag gesture when it is disabled on mobile', (WidgetTester tester) async {
     await tester.pumpWidget(
       MaterialApp(
         home: Scaffold(
@@ -1839,7 +1839,47 @@ void main() {
     await tester.dragFrom(const Offset(300, 100), const Offset(-300, 0));
     await tester.pumpAndSettle();
     expect(scaffoldState.isDrawerOpen, false);
-  });
+  }, variant: TargetPlatformVariant.mobile());
+
+  testWidgets('Drawer does not open with a drag gesture on dekstop', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Scaffold(
+          drawer: const Drawer(
+            child: Text('Drawer'),
+          ),
+          body: const Text('Scaffold Body'),
+          appBar: AppBar(
+            centerTitle: true,
+            title: const Text('Title'),
+          ),
+        ),
+      ),
+    );
+    final ScaffoldState scaffoldState = tester.state(find.byType(Scaffold));
+    expect(scaffoldState.isDrawerOpen, false);
+
+    // Test that we cannot open the drawer with a drag gesture.
+    await tester.dragFrom(const Offset(0, 100), const Offset(300, 0));
+    await tester.pumpAndSettle();
+    expect(scaffoldState.isDrawerOpen, false);
+
+    // Test that we can open the drawer with a tap gesture on drawer icon button.
+    final Finder drawerOpenButton = find.byType(IconButton).first;
+    await tester.tap(drawerOpenButton);
+    await tester.pumpAndSettle();
+    expect(scaffoldState.isDrawerOpen, true);
+
+    // Test that we cannot close the drawer with a drag gesture.
+    await tester.dragFrom(const Offset(300, 100), const Offset(-300, 0));
+    await tester.pumpAndSettle();
+    expect(scaffoldState.isDrawerOpen, true);
+
+    // Test that we can close the drawer with a tap gesture in the body.
+    await tester.tapAt(const Offset(500, 300));
+    await tester.pumpAndSettle();
+    expect(scaffoldState.isDrawerOpen, false);
+  }, variant: TargetPlatformVariant.desktop());
 
   testWidgets('End drawer does not open with a drag gesture when it is disabled', (WidgetTester tester) async {
     late double screenWidth;