Drawer fix (#20015)

* Drawer fix

* fixed nits

* fixed nits

* fixed nits

* final change

* Drawer fix final

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

@@ -141,6 +141,10 @@ class Drawer extends StatelessWidget {
   }
 }
 
+/// Signature for the callback that's called when a [DrawerController] is
+/// opened or closed.
+typedef void DrawerCallback(bool isOpened);
+
 /// Provides interactive behavior for [Drawer] widgets.
 ///
 /// Rarely used directly. Drawer controllers are typically created automatically
@@ -165,6 +169,7 @@ class DrawerController extends StatefulWidget {
     GlobalKey key,
     @required this.child,
     @required this.alignment,
+    this.drawerCallback,
   }) : assert(child != null),
        assert(alignment != null),
        super(key: key);
@@ -180,6 +185,9 @@ class DrawerController extends StatefulWidget {
   /// close the drawer.
   final DrawerAlignment alignment;
 
+  /// Optional callback that is called when a [Drawer] is opened or closed.
+  final DrawerCallback drawerCallback;
+
   @override
   DrawerControllerState createState() => new DrawerControllerState();
 }
@@ -270,6 +278,8 @@ class DrawerControllerState extends State<DrawerController> with SingleTickerPro
     return _kWidth; // drawer not being shown currently
   }
 
+  bool _previouslyOpened = false;
+
   void _move(DragUpdateDetails details) {
     double delta = details.primaryDelta / _width;
     switch (widget.alignment) {
@@ -287,6 +297,11 @@ class DrawerControllerState extends State<DrawerController> with SingleTickerPro
         _controller.value += delta;
         break;
     }
+
+    final bool opened = _controller.value > 0.5 ? true : false;
+    if (opened != _previouslyOpened && widget.drawerCallback != null)
+      widget.drawerCallback(opened);
+    _previouslyOpened = opened;
   }
 
   void _settle(DragEndDetails details) {
@@ -321,11 +336,15 @@ class DrawerControllerState extends State<DrawerController> with SingleTickerPro
   /// Typically called by [ScaffoldState.openDrawer].
   void open() {
     _controller.fling(velocity: 1.0);
+    if (widget.drawerCallback != null)
+      widget.drawerCallback(true);
   }
 
   /// Starts an animation to close the drawer.
   void close() {
     _controller.fling(velocity: -1.0);
+    if (widget.drawerCallback != null)
+      widget.drawerCallback(false);
   }
 
   final ColorTween _color = new ColorTween(begin: Colors.transparent, end: Colors.black54);

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

@@ -1019,6 +1019,21 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin {
   /// Whether this scaffold has a non-null [Scaffold.endDrawer].
   bool get hasEndDrawer => widget.endDrawer != null;
 
+  bool _drawerOpened = false;
+  bool _endDrawerOpened = false;
+
+  void _drawerOpenedCallback(bool isOpened) {
+    setState(() {
+      _drawerOpened = isOpened;
+    });
+  }
+
+  void _endDrawerOpenedCallback(bool isOpened) {
+    setState(() {
+      _endDrawerOpened = isOpened;
+    });
+  }
+
   /// Opens the [Drawer] (if any).
   ///
   /// If the scaffold has a non-null [Scaffold.drawer], this function will cause
@@ -1032,6 +1047,8 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin {
   ///
   /// See [Scaffold.of] for information about how to obtain the [ScaffoldState].
   void openDrawer() {
+    if (_endDrawerKey.currentState != null && _endDrawerOpened)
+      _endDrawerKey.currentState.close();
     _drawerKey.currentState?.open();
   }
 
@@ -1048,6 +1065,8 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin {
   ///
   /// See [Scaffold.of] for information about how to obtain the [ScaffoldState].
   void openEndDrawer() {
+    if (_drawerKey.currentState != null && _drawerOpened)
+      _drawerKey.currentState.close();
     _endDrawerKey.currentState?.open();
   }
 
@@ -1408,6 +1427,48 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin {
     }
   }
 
+  void _buildEndDrawer(List<LayoutId> children, TextDirection textDirection) {
+    if (widget.endDrawer != null) {
+      assert(hasEndDrawer);
+      _addIfNonNull(
+        children,
+        new DrawerController(
+          key: _endDrawerKey,
+          alignment: DrawerAlignment.end,
+          child: widget.endDrawer,
+          drawerCallback: _endDrawerOpenedCallback,
+        ),
+        _ScaffoldSlot.endDrawer,
+        // remove the side padding from the side we're not touching
+        removeLeftPadding: textDirection == TextDirection.ltr,
+        removeTopPadding: false,
+        removeRightPadding: textDirection == TextDirection.rtl,
+        removeBottomPadding: false,
+      );
+    }
+  }
+
+  void _buildDrawer(List<LayoutId> children, TextDirection textDirection) {
+    if (widget.drawer != null) {
+      assert(hasDrawer);
+      _addIfNonNull(
+        children,
+        new DrawerController(
+          key: _drawerKey,
+          alignment: DrawerAlignment.start,
+          child: widget.drawer,
+          drawerCallback: _drawerOpenedCallback,
+        ),
+        _ScaffoldSlot.drawer,
+        // remove the side padding from the side we're not touching
+        removeLeftPadding: textDirection == TextDirection.rtl,
+        removeTopPadding: false,
+        removeRightPadding: textDirection == TextDirection.ltr,
+        removeBottomPadding: false,
+      );
+    }
+  }
+
   @override
   Widget build(BuildContext context) {
     assert(debugCheckHasMediaQuery(context));
@@ -1440,7 +1501,8 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin {
       removeLeftPadding: false,
       removeTopPadding: widget.appBar != null,
       removeRightPadding: false,
-      removeBottomPadding: widget.bottomNavigationBar != null || widget.persistentFooterButtons != null,
+      removeBottomPadding: widget.bottomNavigationBar != null ||
+        widget.persistentFooterButtons != null,
     );
 
     if (widget.appBar != null) {
@@ -1465,7 +1527,8 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin {
     }
 
     if (_snackBars.isNotEmpty) {
-      final bool removeBottomPadding = widget.persistentFooterButtons != null || widget.bottomNavigationBar != null;
+      final bool removeBottomPadding = widget.persistentFooterButtons != null ||
+        widget.bottomNavigationBar != null;
       _addIfNonNull(
         children,
         _snackBars.first._widget,
@@ -1570,40 +1633,12 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin {
       );
     }
 
-    if (widget.drawer != null) {
-      assert(hasDrawer);
-      _addIfNonNull(
-        children,
-        new DrawerController(
-          key: _drawerKey,
-          alignment: DrawerAlignment.start,
-          child: widget.drawer,
-        ),
-        _ScaffoldSlot.drawer,
-        // remove the side padding from the side we're not touching
-        removeLeftPadding: textDirection == TextDirection.rtl,
-        removeTopPadding: false,
-        removeRightPadding: textDirection == TextDirection.ltr,
-        removeBottomPadding: false,
-      );
-    }
-
-    if (widget.endDrawer != null) {
-      assert(hasEndDrawer);
-      _addIfNonNull(
-        children,
-        new DrawerController(
-          key: _endDrawerKey,
-          alignment: DrawerAlignment.end,
-          child: widget.endDrawer,
-        ),
-        _ScaffoldSlot.endDrawer,
-        // remove the side padding from the side we're not touching
-        removeLeftPadding: textDirection == TextDirection.ltr,
-        removeTopPadding: false,
-        removeRightPadding: textDirection == TextDirection.rtl,
-        removeBottomPadding: false,
-      );
+    if (_endDrawerOpened) {
+      _buildDrawer(children, textDirection);
+      _buildEndDrawer(children, textDirection);
+    } else {
+      _buildEndDrawer(children, textDirection);
+      _buildDrawer(children, textDirection);
     }
 
     // The minimum insets for contents of the Scaffold to keep visible.

packages/flutter/test/material/scaffold_test.dart

@@ -766,39 +766,6 @@ void main() {
     expect(tester.getRect(find.byKey(insideDrawer)), new Rect.fromLTRB(596.0, 30.0, 750.0, 540.0));
   });
 
-  testWidgets('Simultaneous drawers on either side', (WidgetTester tester) async {
-    const String bodyLabel = 'I am the body';
-    const String drawerLabel = 'I am the label on start side';
-    const String endDrawerLabel = 'I am the label on end side';
-
-    final SemanticsTester semantics = new SemanticsTester(tester);
-    await tester.pumpWidget(new MaterialApp(home: const Scaffold(
-      body: const Text(bodyLabel),
-      drawer: const Drawer(child: const Text(drawerLabel)),
-      endDrawer: const Drawer(child: const Text(endDrawerLabel)),
-    )));
-
-    expect(semantics, includesNodeWith(label: bodyLabel));
-    expect(semantics, isNot(includesNodeWith(label: drawerLabel)));
-    expect(semantics, isNot(includesNodeWith(label: endDrawerLabel)));
-
-    final ScaffoldState state = tester.firstState(find.byType(Scaffold));
-    state.openDrawer();
-    await tester.pump();
-    await tester.pump(const Duration(seconds: 1));
-
-    expect(semantics, isNot(includesNodeWith(label: bodyLabel)));
-    expect(semantics, includesNodeWith(label: drawerLabel));
-
-    state.openEndDrawer();
-    await tester.pump();
-    await tester.pump(const Duration(seconds: 1));
-
-    expect(semantics, isNot(includesNodeWith(label: bodyLabel)));
-    expect(semantics, includesNodeWith(label: endDrawerLabel));
-
-    semantics.dispose();
-  });
 
   group('ScaffoldGeometry', () {
     testWidgets('bottomNavigationBar', (WidgetTester tester) async {
@@ -969,6 +936,93 @@ void main() {
       numNotificationsAtLastFrame = listenerState.numNotifications;
     });
 
+    testWidgets('Simultaneous drawers on either side', (WidgetTester tester) async {
+      const String bodyLabel = 'I am the body';
+      const String drawerLabel = 'I am the label on start side';
+      const String endDrawerLabel = 'I am the label on end side';
+
+      final SemanticsTester semantics = new SemanticsTester(tester);
+      await tester.pumpWidget(new MaterialApp(home: const Scaffold(
+        body: const Text(bodyLabel),
+        drawer: const Drawer(child: const Text(drawerLabel)),
+        endDrawer: const Drawer(child: const Text(endDrawerLabel)),
+      )));
+
+      expect(semantics, includesNodeWith(label: bodyLabel));
+      expect(semantics, isNot(includesNodeWith(label: drawerLabel)));
+      expect(semantics, isNot(includesNodeWith(label: endDrawerLabel)));
+
+      final ScaffoldState state = tester.firstState(find.byType(Scaffold));
+      state.openDrawer();
+      await tester.pump();
+      await tester.pump(const Duration(seconds: 1));
+
+      expect(semantics, isNot(includesNodeWith(label: bodyLabel)));
+      expect(semantics, includesNodeWith(label: drawerLabel));
+
+      state.openEndDrawer();
+      await tester.pump();
+      await tester.pump(const Duration(seconds: 1));
+
+      expect(semantics, isNot(includesNodeWith(label: bodyLabel)));
+      expect(semantics, includesNodeWith(label: endDrawerLabel));
+
+      semantics.dispose();
+    });
+
+    testWidgets('Dual Drawer Opening', (WidgetTester tester) async {
+
+      await tester.pumpWidget(
+        new MaterialApp(
+          home: new SafeArea(
+            left: false,
+            top: true,
+            right: false,
+            bottom: false,
+            child: new Scaffold(
+              endDrawer: const Drawer(
+                child: const Text('endDrawer'),
+              ),
+              drawer: const Drawer(
+                child: const Text('drawer'),
+              ),
+              body: const Text('scaffold body'),
+              appBar: new AppBar(
+                centerTitle: true,
+                title: const Text('Title')
+              )
+            ),
+          ),
+        ),
+      );
+
+      // Open Drawer, tap on end drawer, which closes the drawer, but does
+      // not open the drawer.
+      await tester.tap(find.byType(IconButton).first);
+      await tester.pumpAndSettle();
+      await tester.tap(find.byType(IconButton).last);
+      await tester.pumpAndSettle();
+
+      expect(find.text('endDrawer'), findsNothing);
+      expect(find.text('drawer'), findsNothing);
+
+      // Tapping the first opens the first drawer
+      await tester.tap(find.byType(IconButton).first);
+      await tester.pumpAndSettle();
+
+      expect(find.text('endDrawer'), findsNothing);
+      expect(find.text('drawer'), findsOneWidget);
+
+      // Tapping on the end drawer and then on the drawer should close the
+      // drawer and then reopen it.
+      await tester.tap(find.byType(IconButton).last);
+      await tester.pumpAndSettle();
+      await tester.tap(find.byType(IconButton).first);
+      await tester.pumpAndSettle();
+
+      expect(find.text('endDrawer'), findsNothing);
+      expect(find.text('drawer'), findsOneWidget);
+    });
   });
 }