[New Feature]Support mouse wheel event on the scrollbar widget (#109659)

* rebase master and add a test

* fix the test

* fix the test

* fix the test

packages/flutter/test/cupertino/scrollbar_test.dart

@@ -1200,6 +1200,8 @@ void main() {
     pointer.hover(const Offset(793.0, 15.0));
     await tester.sendEventToBinding(pointer.scroll(const Offset(0.0, 20.0)));
     await tester.pumpAndSettle();
+
+    if (!kIsWeb) {
       // Scrolling while holding the drag on the scrollbar and still hovered over
       // the scrollbar should not have changed the scroll offset.
       expect(pointer.location, const Offset(793.0, 15.0));
@@ -1214,11 +1216,16 @@ void main() {
           color: _kScrollbarColor.color,
         ),
       );
+    } else {
+      expect(pointer.location, const Offset(793.0, 15.0));
+      expect(scrollController.offset, previousOffset + 20.0);
+    }
+
 
     // Drag is still being held, move pointer to be hovering over another area
     // of the scrollable (not over the scrollbar) and execute another pointer scroll
     pointer.hover(tester.getCenter(find.byType(SingleChildScrollView)));
-    await tester.sendEventToBinding(pointer.scroll(const Offset(0.0, -70.0)));
+    await tester.sendEventToBinding(pointer.scroll(const Offset(0.0, -90.0)));
     await tester.pumpAndSettle();
     // Scrolling while holding the drag on the scrollbar changed the offset
     expect(pointer.location, const Offset(400.0, 300.0));

packages/flutter/test/material/scrollbar_test.dart

@@ -1634,6 +1634,8 @@ void main() {
     pointer.hover(const Offset(798.0, 15.0));
     await tester.sendEventToBinding(pointer.scroll(const Offset(0.0, 20.0)));
     await tester.pumpAndSettle();
+
+    if (!kIsWeb) {
       // Scrolling while holding the drag on the scrollbar and still hovered over
       // the scrollbar should not have changed the scroll offset.
       expect(pointer.location, const Offset(798.0, 15.0));
@@ -1656,11 +1658,15 @@ void main() {
             color: const Color(0x99000000),
           ),
       );
+    } else {
+      expect(pointer.location, const Offset(798.0, 15.0));
+      expect(scrollController.offset, previousOffset + 20.0);
+    }
 
     // Drag is still being held, move pointer to be hovering over another area
     // of the scrollable (not over the scrollbar) and execute another pointer scroll
     pointer.hover(tester.getCenter(find.byType(SingleChildScrollView)));
-    await tester.sendEventToBinding(pointer.scroll(const Offset(0.0, -70.0)));
+    await tester.sendEventToBinding(pointer.scroll(const Offset(0.0, -90.0)));
     await tester.pumpAndSettle();
     // Scrolling while holding the drag on the scrollbar changed the offset
     expect(pointer.location, const Offset(400.0, 300.0));

packages/flutter/test/widgets/scrollbar_test.dart

@@ -1607,6 +1607,8 @@ void main() {
     pointer.hover(const Offset(798.0, 15.0));
     await tester.sendEventToBinding(pointer.scroll(const Offset(0.0, 20.0)));
     await tester.pumpAndSettle();
+
+    if (!kIsWeb) {
       // Scrolling while holding the drag on the scrollbar and still hovered over
       // the scrollbar should not have changed the scroll offset.
       expect(pointer.location, const Offset(798.0, 15.0));
@@ -1629,11 +1631,15 @@ void main() {
             color: const Color(0x66bcbcbc),
           ),
       );
+    } else {
+      expect(pointer.location, const Offset(798.0, 15.0));
+      expect(scrollController.offset, previousOffset + 20.0);
+    }
 
     // Drag is still being held, move pointer to be hovering over another area
     // of the scrollable (not over the scrollbar) and execute another pointer scroll
     pointer.hover(tester.getCenter(find.byType(SingleChildScrollView)));
-    await tester.sendEventToBinding(pointer.scroll(const Offset(0.0, -70.0)));
+    await tester.sendEventToBinding(pointer.scroll(const Offset(0.0, -90.0)));
     await tester.pumpAndSettle();
     // Scrolling while holding the drag on the scrollbar changed the offset
     expect(pointer.location, const Offset(400.0, 300.0));
@@ -2788,4 +2794,50 @@ void main() {
         ),
     );
   });
+
+  testWidgets('The bar support mouse wheel event', (WidgetTester tester) async {
+    // Regression test for https://github.com/flutter/flutter/pull/109659
+    final ScrollController scrollController = ScrollController();
+    Widget buildFrame() {
+      return Directionality(
+        textDirection: TextDirection.ltr,
+        child: MediaQuery(
+          data: const MediaQueryData(),
+          child: PrimaryScrollController(
+            controller: scrollController,
+            child: RawScrollbar(
+              thumbVisibility: true,
+              controller: scrollController,
+              child: const SingleChildScrollView(
+                primary: true,
+                child: SizedBox(
+                  width: double.infinity,
+                  height: 1200.0,
+                ),
+              ),
+            ),
+          ),
+        ),
+      );
+    }
+
+    await tester.pumpWidget(buildFrame());
+    await tester.pumpAndSettle();
+    expect(scrollController.offset, 0.0);
+
+    // Execute a pointer scroll hover on the scroll bar
+    final TestPointer pointer = TestPointer(1, ui.PointerDeviceKind.mouse);
+    pointer.hover(const Offset(798.0, 15.0));
+    await tester.sendEventToBinding(pointer.scroll(const Offset(0.0, 30.0)));
+    await tester.pumpAndSettle();
+
+    expect(scrollController.offset, 30.0);
+
+    // Execute a pointer scroll outside the scroll bar
+    pointer.hover(const Offset(198.0, 15.0));
+    await tester.sendEventToBinding(pointer.scroll(const Offset(0.0, 70.0)));
+    await tester.pumpAndSettle();
+
+    expect(scrollController.offset, 100.0);
+  }, variant: TargetPlatformVariant.all());
 }