[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

@@ -1200,25 +1200,32 @@ void main() {
     pointer.hover(const Offset(793.0, 15.0));
     await tester.sendEventToBinding(pointer.scroll(const Offset(0.0, 20.0)));
     await tester.pumpAndSettle();
-    // 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));
-    expect(scrollController.offset, previousOffset);
-    expect(
-      find.byType(CupertinoScrollbar),
-      paints..rrect(
-        rrect: RRect.fromRectAndRadius(
-          const Rect.fromLTRB(789.0, 13.0, 797.0, 102.1),
-          const Radius.circular(4.0),
+
+    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));
+      expect(scrollController.offset, previousOffset);
+      expect(
+        find.byType(CupertinoScrollbar),
+        paints..rrect(
+          rrect: RRect.fromRectAndRadius(
+            const Rect.fromLTRB(789.0, 13.0, 797.0, 102.1),
+            const Radius.circular(4.0),
+          ),
+          color: _kScrollbarColor.color,
         ),
-        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

@@ -1634,33 +1634,39 @@ void main() {
     pointer.hover(const Offset(798.0, 15.0));
     await tester.sendEventToBinding(pointer.scroll(const Offset(0.0, 20.0)));
     await tester.pumpAndSettle();
-    // 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));
-    expect(scrollController.offset, previousOffset);
-    expect(
-      find.byType(Scrollbar),
-      paints
-        ..rect(
-          rect: const Rect.fromLTRB(796.0, 0.0, 800.0, 600.0),
-          color: Colors.transparent,
-        )
-        ..line(
-          p1: const Offset(796.0, 0.0),
-          p2: const Offset(796.0, 600.0),
-          strokeWidth: 1.0,
-          color: Colors.transparent,
-        )
-        ..rect(
-          rect: const Rect.fromLTRB(796.0, 10.0, 800.0, 100.0),
-          color: const Color(0x99000000),
-        ),
-    );
+
+    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));
+      expect(scrollController.offset, previousOffset);
+      expect(
+        find.byType(Scrollbar),
+        paints
+          ..rect(
+            rect: const Rect.fromLTRB(796.0, 0.0, 800.0, 600.0),
+            color: Colors.transparent,
+          )
+          ..line(
+            p1: const Offset(796.0, 0.0),
+            p2: const Offset(796.0, 600.0),
+            strokeWidth: 1.0,
+            color: Colors.transparent,
+          )
+          ..rect(
+            rect: const Rect.fromLTRB(796.0, 10.0, 800.0, 100.0),
+            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

@@ -1607,33 +1607,39 @@ void main() {
     pointer.hover(const Offset(798.0, 15.0));
     await tester.sendEventToBinding(pointer.scroll(const Offset(0.0, 20.0)));
     await tester.pumpAndSettle();
-    // 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));
-    expect(scrollController.offset, previousOffset);
-    expect(
-      find.byType(RawScrollbar),
-      paints
-        ..rect(
-          rect: const Rect.fromLTRB(794.0, 0.0, 800.0, 600.0),
-          color: const Color(0x00000000),
-        )
-        ..line(
-          p1: const Offset(794.0, 0.0),
-          p2: const Offset(794.0, 600.0),
-          strokeWidth: 1.0,
-          color: const Color(0x00000000),
-        )
-        ..rect(
-          rect: const Rect.fromLTRB(794.0, 10.0, 800.0, 100.0),
-          color: const Color(0x66bcbcbc),
-        ),
-    );
+
+    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));
+      expect(scrollController.offset, previousOffset);
+      expect(
+        find.byType(RawScrollbar),
+        paints
+          ..rect(
+            rect: const Rect.fromLTRB(794.0, 0.0, 800.0, 600.0),
+            color: const Color(0x00000000),
+          )
+          ..line(
+            p1: const Offset(794.0, 0.0),
+            p2: const Offset(794.0, 600.0),
+            strokeWidth: 1.0,
+            color: const Color(0x00000000),
+          )
+          ..rect(
+            rect: const Rect.fromLTRB(794.0, 10.0, 800.0, 100.0),
+            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());
 }