Port RefreshIndicator to slivers (#8218)

This does not attempt to correct any logic, only to port it as written.

The API changed a bit to take into account what is newly available and
no longer available in the new world.

examples/flutter_gallery/lib/demo/overscroll_demo.dart

@@ -20,14 +20,11 @@ class OverscrollDemo extends StatefulWidget {
 class OverscrollDemoState extends State<OverscrollDemo> {
   final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>();
   final GlobalKey<RefreshIndicatorState> _refreshIndicatorKey = new GlobalKey<RefreshIndicatorState>();
-  static final GlobalKey<ScrollableState> _scrollableKey = new GlobalKey<ScrollableState>();
   static final List<String> _items = <String>[
     'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N'
   ];
 
-  IndicatorType _type = IndicatorType.refresh;
-
-  Future<Null> refresh() {
+  Future<Null> _handleRefresh() {
     Completer<Null> completer = new Completer<Null>();
     new Timer(new Duration(seconds: 3), () { completer.complete(null); });
     return completer.future.then((_) {
@@ -45,62 +42,37 @@ class OverscrollDemoState extends State<OverscrollDemo> {
 
   @override
   Widget build(BuildContext context) {
-    Widget body = new Block( // ignore: DEPRECATED_MEMBER_USE
-      padding: const EdgeInsets.all(8.0),
-      scrollableKey: _scrollableKey,
-      children: _items.map((String item) {
-        return new ListItem(
-          isThreeLine: true,
-          leading: new CircleAvatar(child: new Text(item)),
-          title: new Text('This item represents $item.'),
-          subtitle: new Text('Even more additional list item information appears on line three.')
-        );
-      }).toList(),
-    );
-
-    String  indicatorTypeText;
-    switch (_type) {
-      case IndicatorType.overscroll:
-        indicatorTypeText = 'Over-scroll indicator';
-        break;
-      case IndicatorType.refresh:
-        body = new RefreshIndicator(
-          key: _refreshIndicatorKey,
-          refresh: refresh,
-          scrollableKey: _scrollableKey,
-          location: RefreshIndicatorLocation.top,
-          child: body,
-        );
-        indicatorTypeText = 'Refresh indicator';
-        break;
-    }
-
     return new Scaffold(
       key: _scaffoldKey,
       appBar: new AppBar(
-        title: new Text('$indicatorTypeText'),
+        title: new Text('Pull to refresh'),
         actions: <Widget>[
           new IconButton(
             icon: new Icon(Icons.refresh),
-            tooltip: 'Pull to refresh',
+            tooltip: 'Refresh',
             onPressed: () {
-              setState(() {
-                _type = IndicatorType.refresh;
-              });
+              _refreshIndicatorKey.currentState.show();
             }
           ),
-          new IconButton(
-            icon: new Icon(Icons.play_for_work),
-            tooltip: 'Over-scroll indicator',
-            onPressed: () {
-              setState(() {
-                _type = IndicatorType.overscroll;
-              });
-            }
-          )
         ]
       ),
-      body: body
+      body: new RefreshIndicator(
+        key: _refreshIndicatorKey,
+        onRefresh: _handleRefresh,
+        child: new ListView.builder(
+          padding: const EdgeInsets.all(8.0),
+          itemCount: _items.length,
+          itemBuilder: (BuildContext context, int index) {
+            String item = _items[index];
+            return new ListItem(
+              isThreeLine: true,
+              leading: new CircleAvatar(child: new Text(item)),
+              title: new Text('This item represents $item.'),
+              subtitle: new Text('Even more additional list item information appears on line three.'),
+            );
+          },
+        ),
+      ),
     );
   }
 }

packages/flutter/lib/src/widgets/overscroll_indicator.dart

@@ -107,6 +107,9 @@ class _GlowingOverscrollIndicatorState extends State<GlowingOverscrollIndicator>
     }
   }
 
+  Type _lastNotificationType;
+  final Map<bool, bool> _accepted = <bool, bool>{false: true, true: true};
+
   bool _handleScrollNotification(ScrollNotification2 notification) {
     if (notification.depth != 0)
       return false;
@@ -119,27 +122,35 @@ class _GlowingOverscrollIndicatorState extends State<GlowingOverscrollIndicator>
       } else {
         assert(false);
       }
+      bool isLeading = controller == _leadingController;
+      if (_lastNotificationType != OverscrollNotification) {
+        OverscrollIndicatorNotification confirmationNotification = new OverscrollIndicatorNotification(leading: isLeading);
+        confirmationNotification.dispatch(context);
+        _accepted[isLeading] = confirmationNotification._accepted;
+      }
       assert(controller != null);
       assert(notification.axis == config.axis);
-      if (notification.velocity != 0.0) {
-        assert(notification.dragDetails == null);
-        controller.absorbImpact(notification.velocity.abs());
-      } else {
-        assert(notification.overscroll != 0.0);
-        if (notification.dragDetails != null) {
-          assert(notification.dragDetails.globalPosition != null);
-          final RenderBox renderer = notification.context.findRenderObject();
-          assert(renderer != null);
-          assert(renderer.hasSize);
-          final Size size = renderer.size;
-          final Point position = renderer.globalToLocal(notification.dragDetails.globalPosition);
-          switch (notification.axis) {
-            case Axis.horizontal:
-              controller.pull(notification.overscroll.abs(), size.width, position.y.clamp(0.0, size.height), size.height);
-              break;
-            case Axis.vertical:
-              controller.pull(notification.overscroll.abs(), size.height, position.x.clamp(0.0, size.width), size.width);
-              break;
+      if (_accepted[isLeading]) {
+        if (notification.velocity != 0.0) {
+          assert(notification.dragDetails == null);
+          controller.absorbImpact(notification.velocity.abs());
+        } else {
+          assert(notification.overscroll != 0.0);
+          if (notification.dragDetails != null) {
+            assert(notification.dragDetails.globalPosition != null);
+            final RenderBox renderer = notification.context.findRenderObject();
+            assert(renderer != null);
+            assert(renderer.hasSize);
+            final Size size = renderer.size;
+            final Point position = renderer.globalToLocal(notification.dragDetails.globalPosition);
+            switch (notification.axis) {
+              case Axis.horizontal:
+                controller.pull(notification.overscroll.abs(), size.width, position.y.clamp(0.0, size.height), size.height);
+                break;
+              case Axis.vertical:
+                controller.pull(notification.overscroll.abs(), size.height, position.x.clamp(0.0, size.width), size.width);
+                break;
+            }
           }
         }
       }
@@ -149,6 +160,7 @@ class _GlowingOverscrollIndicatorState extends State<GlowingOverscrollIndicator>
         _trailingController.scrollEnd();
       }
     }
+    _lastNotificationType = notification.runtimeType;
     return false;
   }
 
@@ -466,3 +478,24 @@ class _GlowingOverscrollIndicatorPainter extends CustomPainter {
         || oldDelegate.trailingController != trailingController;
   }
 }
+
+class OverscrollIndicatorNotification extends Notification with ViewportNotificationMixin {
+  OverscrollIndicatorNotification({
+    this.leading,
+  });
+
+  final bool leading;
+
+  bool _accepted = true;
+
+  /// Call this method if the glow should be prevented.
+  void disallowGlow() {
+    _accepted = false;
+  }
+
+  @override
+  void debugFillDescription(List<String> description) {
+    super.debugFillDescription(description);
+    description.add('side: ${leading ? "leading edge" : "trailing edge"}');
+  }
+}
\ No newline at end of file

packages/flutter/lib/src/widgets/scroll_notification.dart

@@ -54,7 +54,36 @@ class ScrollMetrics {
   }
 }
 
-abstract class ScrollNotification2 extends LayoutChangedNotification {
+/// Mixin for [Notification]s that track how many [RenderAbstractViewport] they
+/// have bubbled through.
+///
+/// This is used by [ScrollNotification2] and [OverscrollIndicatorNotification].
+abstract class ViewportNotificationMixin extends Notification {
+  /// The number of viewports that this notification has bubbled through.
+  ///
+  /// Typically listeners only respond to notifications with a [depth] of zero.
+  ///
+  /// Specifically, this is the number of [Widget]s representing
+  /// [RenderAbstractViewport] render objects through which this notification
+  /// has bubbled.
+  int get depth => _depth;
+  int _depth = 0;
+
+  @override
+  bool visitAncestor(Element element) {
+    if (element is RenderObjectElement && element.renderObject is RenderAbstractViewport)
+      _depth += 1;
+    return super.visitAncestor(element);
+  }
+
+  @override
+  void debugFillDescription(List<String> description) {
+    super.debugFillDescription(description);
+    description.add('depth: $depth (${ depth == 0 ? "local" : "remote"})');
+  }
+}
+
+abstract class ScrollNotification2 extends LayoutChangedNotification with ViewportNotificationMixin {
   /// Creates a notification about scrolling.
   ScrollNotification2({
     @required Scrollable2State scrollable,
@@ -75,29 +104,11 @@ abstract class ScrollNotification2 extends LayoutChangedNotification {
   /// size of the viewport, for instance.
   final BuildContext context;
 
-  /// The number of viewports that this notification has bubbled through.
-  ///
-  /// Typically listeners only respond to notifications with a [depth] of zero.
-  ///
-  /// Specifically, this is the number of [Widget]s representing
-  /// [RenderAbstractViewport] render objects through which this notification
-  /// has bubbled.
-  int get depth => _depth;
-  int _depth = 0;
-
-  @override
-  bool visitAncestor(Element element) {
-    if (element is RenderObjectElement && element.renderObject is RenderAbstractViewport)
-      _depth += 1;
-    return super.visitAncestor(element);
-  }
-
   @override
   void debugFillDescription(List<String> description) {
     super.debugFillDescription(description);
     description.add('$axisDirection');
     description.add('metrics: $metrics');
-    description.add('depth: $depth (${ depth == 0 ? "local" : "remote"})');
   }
 }
 

packages/flutter/test/material/refresh_indicator_test.dart

@@ -7,8 +7,6 @@ import 'dart:async';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/material.dart';
 
-final GlobalKey<ScrollableState> scrollableKey = new GlobalKey<ScrollableState>();
-
 bool refreshCalled = false;
 
 Future<Null> refresh() {
@@ -26,10 +24,8 @@ void main() {
     refreshCalled = false;
     await tester.pumpWidget(
       new RefreshIndicator(
-        scrollableKey: scrollableKey,
-        refresh: refresh,
-        child: new Block( // ignore: DEPRECATED_MEMBER_USE
-          scrollableKey: scrollableKey,
+        onRefresh: refresh,
+        child: new ListView(
           children: <String>['A', 'B', 'C', 'D', 'E', 'F'].map((String item) {
             return new SizedBox(
               height: 200.0,
@@ -52,15 +48,13 @@ void main() {
     refreshCalled = false;
     await tester.pumpWidget(
       new RefreshIndicator(
-        scrollableKey: scrollableKey,
-        refresh: refresh,
-        location: RefreshIndicatorLocation.bottom,
-        child: new Block( // ignore: DEPRECATED_MEMBER_USE
-          scrollableKey: scrollableKey,
+        onRefresh: refresh,
+        child: new ListView(
+          reverse: true,
           children: <Widget>[
             new SizedBox(
               height: 200.0,
-              child: new Text('X')
+              child: new Text('X'),
             ),
           ],
         ),
@@ -75,18 +69,88 @@ void main() {
     expect(refreshCalled, true);
   });
 
+  testWidgets('RefreshIndicator - top - position', (WidgetTester tester) async {
+    refreshCalled = false;
+    await tester.pumpWidget(
+      new RefreshIndicator(
+        onRefresh: holdRefresh,
+        child: new ListView(
+          children: <Widget>[
+            new SizedBox(
+              height: 200.0,
+              child: new Text('X'),
+            ),
+          ],
+        ),
+      ),
+    );
+
+    await tester.fling(find.text('X'), const Offset(0.0, -300.0), 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)).y, lessThan(300.0));
+  });
+
+  testWidgets('RefreshIndicator - bottom - position', (WidgetTester tester) async {
+    refreshCalled = false;
+    await tester.pumpWidget(
+      new RefreshIndicator(
+        onRefresh: holdRefresh,
+        child: new ListView(
+          reverse: true,
+          children: <Widget>[
+            new SizedBox(
+              height: 200.0,
+              child: new Text('X'),
+            ),
+          ],
+        ),
+      ),
+    );
+
+    await tester.fling(find.text('X'), const Offset(0.0, -300.0), 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)).y, greaterThan(300.0));
+  });
+
+  testWidgets('RefreshIndicator - no movement', (WidgetTester tester) async {
+    refreshCalled = false;
+    await tester.pumpWidget(
+      new RefreshIndicator(
+        onRefresh: refresh,
+        child: new ListView(
+          children: <Widget>[
+            new SizedBox(
+              height: 200.0,
+              child: new Text('X'),
+            ),
+          ],
+        ),
+      ),
+    );
+
+    // this fling is horizontal, not up or down
+    await tester.fling(find.text('X'), const Offset(1.0, 0.0), 1000.0);
+    await tester.pump();
+    await tester.pump(const Duration(seconds: 1));
+    await tester.pump(const Duration(seconds: 1));
+    await tester.pump(const Duration(seconds: 1));
+    expect(refreshCalled, false);
+  });
+
   testWidgets('RefreshIndicator - not enough', (WidgetTester tester) async {
     refreshCalled = false;
     await tester.pumpWidget(
       new RefreshIndicator(
-        scrollableKey: scrollableKey,
-        refresh: refresh,
-        child: new Block( // ignore: DEPRECATED_MEMBER_USE
-          scrollableKey: scrollableKey,
+        onRefresh: refresh,
+        child: new ListView(
           children: <Widget>[
             new SizedBox(
               height: 200.0,
-              child: new Text('X')
+              child: new Text('X'),
             ),
           ],
         ),
@@ -105,14 +169,12 @@ void main() {
     refreshCalled = false;
     await tester.pumpWidget(
       new RefreshIndicator(
-        scrollableKey: scrollableKey,
-        refresh: holdRefresh, // this one never returns
-        child: new Block( // ignore: DEPRECATED_MEMBER_USE
-          scrollableKey: scrollableKey,
+        onRefresh: holdRefresh, // this one never returns
+        child: new ListView(
           children: <Widget>[
             new SizedBox(
               height: 200.0,
-              child: new Text('X')
+              child: new Text('X'),
             ),
           ],
         ),
@@ -147,14 +209,12 @@ void main() {
     refreshCalled = false;
     await tester.pumpWidget(
       new RefreshIndicator(
-        scrollableKey: scrollableKey,
-        refresh: refresh,
-        child: new Block( // ignore: DEPRECATED_MEMBER_USE
-          scrollableKey: scrollableKey,
+        onRefresh: refresh,
+        child: new ListView(
           children: <Widget>[
             new SizedBox(
               height: 200.0,
-              child: new Text('X')
+              child: new Text('X'),
             ),
           ],
         ),
@@ -190,14 +250,12 @@ void main() {
     refreshCalled = false;
     await tester.pumpWidget(
       new RefreshIndicator(
-        scrollableKey: scrollableKey,
-        refresh: refresh,
-        child: new Block( // ignore: DEPRECATED_MEMBER_USE
-          scrollableKey: scrollableKey,
+        onRefresh: refresh,
+        child: new ListView(
           children: <Widget>[
             new SizedBox(
               height: 200.0,
-              child: new Text('X')
+              child: new Text('X'),
             ),
           ],
         ),