Show `RefreshIndicator` on top when scroll's axis direction is up (matching...

Show `RefreshIndicator` on top when scroll's axis direction is up (matching native behaviour) (#93779)

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

@@ -296,7 +296,8 @@ class RefreshIndicatorState extends State<RefreshIndicator> with TickerProviderS
     // In this case, we don't want to trigger the refresh indicator.
     return ((notification is ScrollStartNotification && notification.dragDetails != null)
             || (notification is ScrollUpdateNotification && notification.dragDetails != null && widget.triggerMode == RefreshIndicatorTriggerMode.anywhere))
-      && notification.metrics.extentBefore == 0.0
+      && (( notification.metrics.axisDirection == AxisDirection.up && notification.metrics.extentAfter == 0.0)
+            || (notification.metrics.axisDirection == AxisDirection.down && notification.metrics.extentBefore == 0.0))
       && _mode == null
       && _start(notification.metrics.axisDirection);
   }
@@ -313,10 +314,8 @@ class RefreshIndicatorState extends State<RefreshIndicator> with TickerProviderS
     bool? indicatorAtTopNow;
     switch (notification.metrics.axisDirection) {
       case AxisDirection.down:
-        indicatorAtTopNow = true;
-        break;
       case AxisDirection.up:
-        indicatorAtTopNow = false;
+        indicatorAtTopNow = true;
         break;
       case AxisDirection.left:
       case AxisDirection.right:
@@ -328,10 +327,15 @@ class RefreshIndicatorState extends State<RefreshIndicator> with TickerProviderS
         _dismiss(_RefreshIndicatorMode.canceled);
     } else if (notification is ScrollUpdateNotification) {
       if (_mode == _RefreshIndicatorMode.drag || _mode == _RefreshIndicatorMode.armed) {
-        if (notification.metrics.extentBefore > 0.0) {
+        if ((notification.metrics.axisDirection  == AxisDirection.down && notification.metrics.extentBefore > 0.0)
+            || (notification.metrics.axisDirection  == AxisDirection.up && notification.metrics.extentAfter > 0.0)) {
           _dismiss(_RefreshIndicatorMode.canceled);
         } else {
-          _dragOffset = _dragOffset! - notification.scrollDelta!;
+          if (notification.metrics.axisDirection == AxisDirection.down) {
+            _dragOffset = _dragOffset! - notification.scrollDelta!;
+          } else if (notification.metrics.axisDirection == AxisDirection.up) {
+            _dragOffset = _dragOffset! + notification.scrollDelta!;
+          }
           _checkDragOffset(notification.metrics.viewportDimension);
         }
       }
@@ -343,7 +347,11 @@ class RefreshIndicatorState extends State<RefreshIndicator> with TickerProviderS
       }
     } else if (notification is OverscrollNotification) {
       if (_mode == _RefreshIndicatorMode.drag || _mode == _RefreshIndicatorMode.armed) {
-        _dragOffset = _dragOffset! - notification.overscroll;
+        if (notification.metrics.axisDirection == AxisDirection.down) {
+          _dragOffset = _dragOffset! - notification.overscroll;
+        } else if (notification.metrics.axisDirection == AxisDirection.up) {
+          _dragOffset = _dragOffset! + notification.overscroll;
+        }
         _checkDragOffset(notification.metrics.viewportDimension);
       }
     } else if (notification is ScrollEndNotification) {
@@ -382,10 +390,8 @@ class RefreshIndicatorState extends State<RefreshIndicator> with TickerProviderS
     assert(_dragOffset == null);
     switch (direction) {
       case AxisDirection.down:
-        _isIndicatorAtTop = true;
-        break;
       case AxisDirection.up:
-        _isIndicatorAtTop = false;
+        _isIndicatorAtTop = true;
         break;
       case AxisDirection.left:
       case AxisDirection.right:

packages/flutter/test/material/refresh_indicator_test.dart

@@ -95,7 +95,7 @@ void main() {
     expect(refreshCalled, true);
   });
 
-  testWidgets('RefreshIndicator - bottom', (WidgetTester tester) async {
+  testWidgets('RefreshIndicator - reverse', (WidgetTester tester) async {
     refreshCalled = false;
     await tester.pumpWidget(
       MaterialApp(
@@ -115,7 +115,7 @@ void main() {
       ),
     );
 
-    await tester.fling(find.text('X'), const Offset(0.0, -300.0), 1000.0);
+    await tester.fling(find.text('X'), const Offset(0.0, 600.0), 1000.0);
     await tester.pump();
     await tester.pump(const Duration(seconds: 1)); // finish the scroll animation
     await tester.pump(const Duration(seconds: 1)); // finish the indicator settle animation
@@ -149,7 +149,7 @@ void main() {
     expect(tester.getCenter(find.byType(RefreshProgressIndicator)).dy, lessThan(300.0));
   });
 
-  testWidgets('RefreshIndicator - bottom - position', (WidgetTester tester) async {
+  testWidgets('RefreshIndicator - reverse - position', (WidgetTester tester) async {
     refreshCalled = false;
     await tester.pumpWidget(
       MaterialApp(
@@ -169,11 +169,11 @@ void main() {
       ),
     );
 
-    await tester.fling(find.text('X'), const Offset(0.0, -300.0), 1000.0);
+    await tester.fling(find.text('X'), const Offset(0.0, 600.0), 1000.0);
     await tester.pump();
     await tester.pump(const Duration(seconds: 1));
     await tester.pump(const Duration(seconds: 1));
-    expect(tester.getCenter(find.byType(RefreshProgressIndicator)).dy, greaterThan(300.0));
+    expect(tester.getCenter(find.byType(RefreshProgressIndicator)).dy, lessThan(300.0));
   });
 
   testWidgets('RefreshIndicator - no movement', (WidgetTester tester) async {
@@ -612,7 +612,7 @@ void main() {
     expect(tester.getCenter(find.byType(RefreshProgressIndicator)).dy, lessThan(300.0));
   });
 
-  testWidgets('Bottom RefreshIndicator(anywhere mode) should be shown when dragging from non-zero scroll position', (WidgetTester tester) async {
+  testWidgets('Reverse RefreshIndicator(anywhere mode) should be shown when dragging from non-zero scroll position', (WidgetTester tester) async {
     refreshCalled = false;
     final ScrollController scrollController = ScrollController();
     await tester.pumpWidget(
@@ -641,11 +641,11 @@ void main() {
 
     scrollController.jumpTo(50.0);
 
-    await tester.fling(find.text('X'), const Offset(0.0, -300.0), 1000.0);
+    await tester.fling(find.text('X'), const Offset(0.0, 600.0), 1000.0);
     await tester.pump();
     await tester.pump(const Duration(seconds: 1)); // finish the scroll animation
     await tester.pump(const Duration(seconds: 1)); // finish the indicator settle animation
-    expect(tester.getCenter(find.byType(RefreshProgressIndicator)).dy, greaterThan(300.0));
+    expect(tester.getCenter(find.byType(RefreshProgressIndicator)).dy, lessThan(300.0));
   });
 
   // Regression test for https://github.com/flutter/flutter/issues/71936
@@ -719,7 +719,7 @@ void main() {
     expect(find.byType(RefreshProgressIndicator), findsNothing);
   });
 
-  testWidgets('Bottom RefreshIndicator(onEdge mode) should be shown when dragging from non-zero scroll position', (WidgetTester tester) async {
+  testWidgets('Reverse RefreshIndicator(onEdge mode) should be shown when dragging from non-zero scroll position', (WidgetTester tester) async {
     refreshCalled = false;
     final ScrollController scrollController = ScrollController();
     await tester.pumpWidget(
@@ -817,7 +817,7 @@ void main() {
       ),
     );
 
-    await tester.fling(find.text('X'), const Offset(0.0, -300.0), 1000.0);
+    await tester.fling(find.text('X'), const Offset(0.0, 600.0), 1000.0);
     await tester.pump();
     expect(tester.widget<RefreshProgressIndicator>(find.byType(RefreshProgressIndicator)).valueColor!.value, primaryColor);
   });
@@ -857,7 +857,7 @@ void main() {
       ),
     );
 
-    await tester.fling(find.text('X'), const Offset(0.0, -300.0), 1000.0);
+    await tester.fling(find.text('X'), const Offset(0.0, 600.0), 1000.0);
     await tester.pump();
     expect(tester.widget<RefreshProgressIndicator>(find.byType(RefreshProgressIndicator)).valueColor!.value, refreshIndicatorColor.withOpacity(1.0));
 
@@ -868,4 +868,38 @@ void main() {
     await tester.pump();
     expect(tester.widget<RefreshProgressIndicator>(find.byType(RefreshProgressIndicator)).valueColor!.value, red.withOpacity(1.0));
   });
+
+  testWidgets('RefreshIndicator - reverse - BouncingScrollPhysics', (WidgetTester tester) async {
+    refreshCalled = false;
+    await tester.pumpWidget(
+      MaterialApp(
+        home: RefreshIndicator(
+          onRefresh: refresh,
+          child: ListView(
+            reverse: true,
+            physics: const BouncingScrollPhysics(),
+            children: <Widget>[
+              for (int i = 0; i < 4; i++)
+                SizedBox(
+                  height: 200.0,
+                  child: Text('X - $i'),
+                ),
+            ],
+          )
+        ),
+      ),
+    );
+
+    // Scroll to top
+    await tester.fling(find.text('X - 0'), const Offset(0.0, 800.0), 1000.0);
+    await tester.pumpAndSettle();
+
+    // Fling down to show refresh indicator
+    await tester.fling(find.text('X - 3'), const Offset(0.0, 250.0), 1000.0);
+    await tester.pump();
+    await tester.pump(const Duration(seconds: 1)); // finish the scroll animation
+    await tester.pump(const Duration(seconds: 1)); // finish the indicator settle animation
+    await tester.pump(const Duration(seconds: 1)); // finish the indicator hide animation
+    expect(refreshCalled, true);
+  });
 }