From dc432d78db349bb02aeee23c8e75c2acdee7702c Mon Sep 17 00:00:00 2001
From: Bikram Pandit <bikcrum@gmail.com>
Date: Tue, 1 Dec 2020 23:28:06 +0545
Subject: [PATCH] Add detection of drawer open and close in Scaffold widget as
 a callback method. (#67249)

---
 .../flutter/lib/src/material/scaffold.dart    | 10 +++++
 .../flutter/test/material/scaffold_test.dart  | 38 +++++++++++++++++++
 2 files changed, 48 insertions(+)

diff --git a/packages/flutter/lib/src/material/scaffold.dart b/packages/flutter/lib/src/material/scaffold.dart
index 7e89bf5430..f4bd4418de 100644
--- a/packages/flutter/lib/src/material/scaffold.dart
+++ b/packages/flutter/lib/src/material/scaffold.dart
@@ -1443,7 +1443,9 @@ class Scaffold extends StatefulWidget {
     this.floatingActionButtonAnimator,
     this.persistentFooterButtons,
     this.drawer,
+    this.onDrawerChanged,
     this.endDrawer,
+    this.onEndDrawerChanged,
     this.bottomNavigationBar,
     this.bottomSheet,
     this.backgroundColor,
@@ -1607,6 +1609,9 @@ class Scaffold extends StatefulWidget {
   /// {@end-tool}
   final Widget? drawer;
 
+  /// Optional callback that is called when the [Scaffold.drawer] is opened or closed.
+  final DrawerCallback? onDrawerChanged;
+
   /// A panel displayed to the side of the [body], often hidden on mobile
   /// devices. Swipes in from right-to-left ([TextDirection.ltr]) or
   /// left-to-right ([TextDirection.rtl])
@@ -1667,6 +1672,9 @@ class Scaffold extends StatefulWidget {
   /// {@end-tool}
   final Widget? endDrawer;
 
+  /// Optional callback that is called when the [Scaffold.endDrawer] is opened or closed.
+  final DrawerCallback? onEndDrawerChanged;
+
   /// The color to use for the scrim that obscures primary content while a drawer is open.
   ///
   /// By default, the color is [Colors.black54]
@@ -2091,12 +2099,14 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin {
     setState(() {
       _drawerOpened = isOpened;
     });
+    widget.onDrawerChanged?.call(isOpened);
   }
 
   void _endDrawerOpenedCallback(bool isOpened) {
     setState(() {
       _endDrawerOpened = isOpened;
     });
+    widget.onEndDrawerChanged?.call(isOpened);
   }
 
   /// Opens the [Drawer] (if any).
diff --git a/packages/flutter/test/material/scaffold_test.dart b/packages/flutter/test/material/scaffold_test.dart
index 439e3c6c25..38539d8796 100644
--- a/packages/flutter/test/material/scaffold_test.dart
+++ b/packages/flutter/test/material/scaffold_test.dart
@@ -11,6 +11,44 @@ import 'package:flutter_test/flutter_test.dart';
 import '../widgets/semantics_tester.dart';
 
 void main() {
+  testWidgets('Scaffold drawer callback test', (WidgetTester tester) async {
+    bool isDrawerOpen = false;
+    bool isEndDrawerOpen = false;
+
+    await tester.pumpWidget(MaterialApp(
+      home: Scaffold(
+          drawer: Container(
+            color: Colors.blue,
+          ),
+          onDrawerChanged: (bool isOpen) {
+            isDrawerOpen = isOpen;
+          },
+          endDrawer: Container(
+            color: Colors.green,
+          ),
+          onEndDrawerChanged: (bool isOpen) {
+            isEndDrawerOpen = isOpen;
+          },
+          body: Container()),
+    ));
+
+    final ScaffoldState scaffoldState = tester.state(find.byType(Scaffold));
+
+    scaffoldState.openDrawer();
+    await tester.pumpAndSettle();
+    expect(true, isDrawerOpen);
+    scaffoldState.openEndDrawer();
+    await tester.pumpAndSettle();
+    expect(false, isDrawerOpen);
+
+    scaffoldState.openEndDrawer();
+    await tester.pumpAndSettle();
+    expect(true, isEndDrawerOpen);
+    scaffoldState.openDrawer();
+    await tester.pumpAndSettle();
+    expect(false, isEndDrawerOpen);
+  });
+
   testWidgets('Scaffold control test', (WidgetTester tester) async {
     final Key bodyKey = UniqueKey();
     Widget boilerplate(Widget child) {