RefreshIndicator backgroundColor (#4924)

examples/flutter_gallery/lib/demo/overscroll_demo.dart

@@ -31,15 +31,18 @@ class OverscrollDemoState extends State<OverscrollDemo> {
     Completer<Null> completer = new Completer<Null>();
     new Timer(new Duration(seconds: 3), () { completer.complete(null); });
     return completer.future.then((_) {
-      _scaffoldKey.currentState.showSnackBar(new SnackBar(
-       content: new Text("Refresh complete"),
-       action: new SnackBarAction(
-         label: 'RETRY',
-         onPressed: () {
-           _refreshIndicatorKey.currentState.show();
-         }
-       )
-      ));
+      final ScaffoldState scaffoldState = _scaffoldKey.currentState;
+      if (scaffoldState != null) {
+         scaffoldState.showSnackBar(new SnackBar(
+           content: new Text("Refresh complete"),
+           action: new SnackBarAction(
+             label: 'RETRY',
+             onPressed: () {
+               _refreshIndicatorKey.currentState.show();
+             }
+           )
+         ));
+       }
     });
   }
 

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

@@ -46,14 +46,15 @@ abstract class ProgressIndicator extends StatefulWidget {
   /// much actual progress is being made.
   final double value;
 
-  /// The progress indicator's background color. If null, the background color is
-  /// the current theme's backgroundColor.
+  /// The progress indicator's background color. The current theme's
+  /// [ThemeData.backgroundColor] by default.
   final Color backgroundColor;
 
   /// The indicator's color is the animation's value. To specify a constant
   /// color use: `new AlwaysStoppedAnimation<Color>(color)`.
   ///
-  /// If null, the progress indicator is rendered with the current theme's primaryColor.
+  /// If null, the progress indicator is rendered with the current theme's
+  /// [ThemeData.primaryColor].
   final Animation<Color> valueColor;
 
   Color _getBackgroundColor(BuildContext context) => backgroundColor ?? Theme.of(context).backgroundColor;
@@ -485,7 +486,7 @@ class _RefreshProgressIndicatorState extends _CircularProgressIndicatorState {
       margin: const EdgeInsets.all(4.0), // acommodate the shadow
       child: new Material(
         type: MaterialType.circle,
-        color: Theme.of(context).canvasColor,
+        color: config.backgroundColor ?? Theme.of(context).canvasColor,
         elevation: 2,
         child: new Padding(
           padding: const EdgeInsets.all(12.0),

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

@@ -68,18 +68,20 @@ enum _DismissTransition {
 /// animated circular progress indicator is faded into view. When the scroll
 /// ends, if the indicator has been dragged far enough for it to become
 /// completely opaque, the refresh callback is called. The callback is
-/// expected to udpate the scrollback and then complete the Future it
-/// returns. The refresh indicator disappears after the callback's
+/// expected to update the scrollable's contents and then complete the Future
+/// it returns. The refresh indicator disappears after the callback's
 /// Future has completed.
 ///
 /// The required [scrollableKey] parameter identifies the scrollable widget
 /// whose scrollOffset is monitored by this RefreshIndicator. The same
-/// scrollableKey must also be set on the scrollable. See [Block.scrollableKey]
+/// scrollableKey must also be set on the scrollable. See [Block.scrollableKey],
 /// [ScrollableList.scrollableKey], etc.
 ///
 /// See also:
 ///
 ///  * <https://www.google.com/design/spec/patterns/swipe-to-refresh.html>
+///  * [RefreshIndicatorState] (can be used to programatically show the refresh indicator)
+///  * [RefreshProgressIndicator]
 class RefreshIndicator extends StatefulWidget {
   /// Creates a refresh indicator.
   ///
@@ -91,7 +93,9 @@ class RefreshIndicator extends StatefulWidget {
     this.child,
     this.displacement: 40.0,
     this.refresh,
-    this.location: RefreshIndicatorLocation.top
+    this.location: RefreshIndicatorLocation.top,
+    this.color,
+    this.backgroundColor
   }) : super(key: key) {
     assert(child != null);
     assert(refresh != null);
@@ -116,10 +120,18 @@ class RefreshIndicator extends StatefulWidget {
   /// Future must complete when the refresh operation is finished.
   final RefreshCallback refresh;
 
-  /// Where the refresh indicator should appear, RefreshIndicatorLocation.top
+  /// Where the refresh indicator should appear, [RefreshIndicatorLocation.top]
   /// by default.
   final RefreshIndicatorLocation location;
 
+  /// The progress indicator's foreground color. The current theme's
+  /// [ThemeData.primaryColor] by default.
+  final Color color;
+
+  /// The progress indicator's background color. The current theme's
+  /// [ThemeData.canvasColor] by default.
+  final Color backgroundColor;
+
   @override
   RefreshIndicatorState createState() => new RefreshIndicatorState();
 }
@@ -156,8 +168,8 @@ class RefreshIndicatorState extends State<RefreshIndicator> {
 
     // Fully opaque when we've reached config.displacement.
     _valueColor = new ColorTween(
-      begin: theme.primaryColor.withOpacity(0.0),
-      end: theme.primaryColor.withOpacity(1.0)
+      begin: (config.color ?? theme.primaryColor).withOpacity(0.0),
+      end: (config.color ?? theme.primaryColor).withOpacity(1.0)
     )
     .animate(new CurvedAnimation(
       parent: _sizeController,
@@ -369,7 +381,8 @@ class RefreshIndicatorState extends State<RefreshIndicator> {
                       builder: (BuildContext context, Widget child) {
                         return new RefreshProgressIndicator(
                           value: showIndeterminateIndicator ? null : _value.value,
-                          valueColor: _valueColor
+                          valueColor: _valueColor,
+                          backgroundColor: config.backgroundColor
                         );
                       }
                     )