Adding support for the MouseWheel event in Streams.

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index 06869b4f5f5eb528e46dc852563729ace9dea4e6..5da857794df1a15b7aab6a1e93b7c715f762c30e 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -8460,6 +8460,23 @@ abstract class Element extends Node implements ElementTraversal native "*Element
   @Creates('Null')  // Set from Dart code; does not instantiate a native type.
   var xtag;
 
+  static const EventStreamProvider<WheelEvent> mouseWheelEvent =
+      const _CustomEventStreamProvider<WheelEvent>(
+        Element._determineMouseWheelEventType);
+
+  static String _determineMouseWheelEventType(EventTarget e) {
+    if (JS('bool', '#.onwheel !== undefined', e)) {
+      // W3C spec, and should be IE9+, but IE has a bug exposing onwheel.
+      return 'wheel';
+    } else if (JS('bool', '#.onmousewheel !== undefined', e)) {
+      // Chrome & IE
+      return 'mousewheel';
+    } else {
+      // Firefox
+      return 'DOMMouseScroll';
+    }
+  }
+
   /**
    * Creates a text node and inserts it into the DOM at the specified location.
    *
@@ -9013,6 +9030,8 @@ abstract class Element extends Node implements ElementTraversal native "*Element
 
   Stream<MouseEvent> get onMouseUp => mouseUpEvent.forTarget(this);
 
+  Stream<WheelEvent> get onMouseWheel => mouseWheelEvent.forTarget(this);
+
   Stream<Event> get onPaste => pasteEvent.forTarget(this);
 
   Stream<Event> get onReset => resetEvent.forTarget(this);
@@ -23887,13 +23906,75 @@ class WebSocketEvents extends Events {
 @DomName('WheelEvent')
 class WheelEvent extends MouseEvent native "*WheelEvent" {
 
+  factory WheelEvent(String type, Window view, int wheelDeltaX, int wheelDeltaY,
+      int detail, int screenX, int screenY, int clientX, int clientY,
+      int button,
+      [bool canBubble = true, bool cancelable = true, bool ctrlKey = false,
+      bool altKey = false, bool shiftKey = false, bool metaKey = false,
+      EventTarget relatedTarget = null]) {
+
+    var eventType = 'WheelEvent';
+    if (_Device.isFirefox) {
+      eventType = 'MouseScrollEvents';
+    }
+    final event = document.$dom_createEvent(eventType);
+    if (event._hasInitWheelEvent) {
+      var modifiers = [];
+      if (ctrlKey) {
+        modifiers.push('Control');
+      }
+      if (altKey) {
+        modifiers.push('Alt');
+      }
+      if (shiftKey) {
+        modifiers.push('Shift');
+      }
+      if (metaKey) {
+        modifiers.push('Meta');
+      }
+      event._initWheelEvent(type, canBubble, cancelable, view, detail, screenX,
+          screenY, clientX, clientY, button, relatedTarget, modifiers.join(' '),
+          wheelDeltaX, wheelDeltaY, 0, 0);
+    } else if (event._hasInitMouseScrollEvent) {
+      var axis = 0;
+      var detail = 0;
+      if (wheelDeltaX != 0 && wheelDeltaY != 0) {
+        throw UnsupportedError(
+            'Cannot modify wheelDeltaX and wheelDeltaY simultaneously');
+      }
+      if (wheelDeltaY != 0) {
+        detail = wheelDeltaY;
+        axis = JS('int', 'MouseScrollEvent.VERTICAL_AXIS');
+      } else if (wheelDeltaX != 0) {
+        detail = wheelDeltaX;
+        axis = JS('int', 'MouseScrollEvent.HORIZONTAL_AXIS');
+      }
+      event._initMouseScrollEvent(type, canBubble, cancelable, view, detail,
+          screenX, screenY, clientX, clientY, ctrlKey, altKey, shiftKey,
+          metaKey, button, relatedTarget, axis);
+    } else {
+      // Fallthrough for Dartium.
+      event.$dom_initMouseEvent(type, canBubble, cancelable, view, detail,
+          screenX, screenY, clientX, clientY, ctrlKey, altKey, shiftKey,
+          metaKey, button, relatedTarget);
+      event.$dom_initWebKitWheelEvent(wheelDeltaX,
+          (wheelDeltaY / 120).toInt(), // Chrome does an auto-convert to pixels.
+          view, screenX, screenY, clientX, clientY, ctrlKey, altKey, shiftKey,
+          metaKey);
+    }
+
+    return event;
+  }
+
+
   /// @docsEditable true
   @DomName('WheelEvent.webkitDirectionInvertedFromDevice')
   final bool webkitDirectionInvertedFromDevice;
 
   /// @docsEditable true
+  @JSName('initWebKitWheelEvent')
   @DomName('WheelEvent.initWebKitWheelEvent')
-  void initWebKitWheelEvent(int wheelDeltaX, int wheelDeltaY, Window view, int screenX, int screenY, int clientX, int clientY, bool ctrlKey, bool altKey, bool shiftKey, bool metaKey) native;
+  void $dom_initWebKitWheelEvent(int wheelDeltaX, int wheelDeltaY, Window view, int screenX, int screenY, int clientX, int clientY, bool ctrlKey, bool altKey, bool shiftKey, bool metaKey) native;
 
 
   @DomName('WheelEvent.deltaY')
@@ -23938,7 +24019,8 @@ class WheelEvent extends MouseEvent native "*WheelEvent" {
 
       // Handle DOMMouseScroll case where it uses detail and the axis to
       // differentiate.
-      if (JS('bool', '#.axis !== undefined && #.axis == MouseScrollEvent.HORIZONTAL_AXIS', this, this)) {
+      if (JS('bool', '#.axis !== undefined && '
+        '#.axis == MouseScrollEvent.HORIZONTAL_AXIS', this, this)) {
         var detail = this._detail;
         // Firefox is normally the number of lines to scale (normally 3)
         // so multiply it by 40 to get pixels to move, matching IE & WebKit.
@@ -23968,6 +24050,49 @@ class WheelEvent extends MouseEvent native "*WheelEvent" {
   num get _detail => JS('num', '#.detail', this);
   int get _deltaMode => JS('int', '#.deltaMode', this);
 
+  bool get _hasInitMouseScrollEvent =>
+      JS('bool', '!!(#.initMouseScrollEvent)', this);
+
+  @JSName('initMouseScrollEvent')
+  void _initMouseScrollEvent(
+      String type,
+      bool canBubble,
+      bool cancelable,
+      Window view,
+      int detail,
+      int screenX,
+      int screenY,
+      int clientX,
+      int clientY,
+      bool ctrlKey,
+      bool altKey,
+      bool shiftKey,
+      bool metaKey,
+      int button,
+      EventTarget relatedTarget,
+      int axis) native;
+
+  bool get _hasInitWheelEvent =>
+      JS('bool', '!!(#.initWheelEvent)', this);
+  @JSName('initWheelEvent')
+  void _initWheelEvent(
+      String eventType,
+      bool canBubble,
+      bool cancelable,
+      Window view,
+      int detail,
+      int screenX,
+      int screenY,
+      int clientX,
+      int clientY,
+      int button,
+      EventTarget relatedTarget,
+      String modifiersList,
+      int deltaX,
+      int deltaY,
+      int deltaZ,
+      int deltaMode) native;
+
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -27820,6 +27945,21 @@ class EventStreamProvider<T extends Event> {
     return new _EventStream(e, _eventType, useCapture);
   }
 }
+
+/**
+ * A factory to expose DOM events as streams, where the DOM event name has to
+ * be determined on the fly (for example, mouse wheel events).
+ */
+class _CustomEventStreamProvider<T extends Event>
+    implements EventStreamProvider<T> {
+
+  final _eventTypeGetter;
+  const _CustomEventStreamProvider(this._eventTypeGetter);
+
+  Stream<T> forTarget(EventTarget e, {bool useCapture: false}) {
+    return new _EventStream(e, _eventTypeGetter(e), useCapture);
+  }
+}
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.