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 78fb2021d8aa49eba670151b5c59a0d985b8c64c..1d03ea66be4c4031f3db25759620b3755d2078a4 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -7963,6 +7963,23 @@ 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.
    *
@@ -8453,6 +8470,8 @@ 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);
@@ -21777,11 +21796,135 @@ 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]) {

[Siggi Cherem (dart-lang), 2013/01/16 18:52:00]

generally indentation here looks strange. Consider combining these 16 lines into
a couple? (same below on the method calls)

[blois, 2013/01/16 20:04:02]

Updated. In general I find the collapsed form fairly unreadable for long lists,
but that is the convention.

+
+    var eventType = 'WheelEvent';
+    if (_Device.isFirefox) {
+      eventType = 'MouseScrollEvents';
+    }
+    final event = document.$dom_createEvent(eventType);
+
+    if (_Device.isWebKit) {
+      event.$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);
+    }
+    else if (_Device.isIE) {

[Siggi Cherem (dart-lang), 2013/01/16 18:52:00]

move else to previous line?

[blois, 2013/01/16 20:04:02]

Was a by-product of template expansion, updated with new format in later patch.

+      var modifiers = [];
+      if (ctrlKey) {
+        modifiers.push('Control');
+      }
+      if (altKey) {
+        modifiers.push('Alt');
+      }
+      if (shiftKey) {
+        modifiers.push('Shift');
+      }
+      if (metaKey) {
+        modifiers.push('Meta');
+      }
+      var modifiersList = modifiers.join(' ');
+      event._initIEWheelEvent(
+        type,
+        canBubble,
+        cancelable,
+        view,
+        detail,
+        screenX,
+        screenY,
+        clientX,
+        clientY,
+        button,
+        relatedTarget,
+        modifiersList,

[Siggi Cherem (dart-lang), 2013/01/16 18:52:00]

nit: maybe simply inline modifiers.join(' ') here?

[blois, 2013/01/16 20:04:02]

Done.

+        wheelDeltaX,
+        wheelDeltaY,
+        0,
+        0);
+    } else if (_Device.isFirefox) {
+      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._initFireFoxMouseScrollEvent(
+        type,
+        canBubble,
+        cancelable,
+        view,
+        detail,
+        screenX,
+        screenY,
+        clientX,
+        clientY,
+        ctrlKey,
+        altKey,
+        shiftKey,
+        metaKey,
+        button,
+        relatedTarget,
+        axis);
+    }
+    return event;
+  }
+
+
   /// @domName WheelEvent.webkitDirectionInvertedFromDevice; @docsEditable true
   final bool webkitDirectionInvertedFromDevice;
 
   /// @domName WheelEvent.initWebKitWheelEvent; @docsEditable true
-  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;
+  @JSName('initWebKitWheelEvent')
+  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 */
@@ -21856,6 +21999,44 @@ class WheelEvent extends MouseEvent native "*WheelEvent" {
   num get _detail => JS('num', '#.detail', this);
   int get _deltaMode => JS('int', '#.deltaMode', this);
 
+  @JSName('initMouseScrollEvent')
+  void _initFireFoxMouseScrollEvent(
+      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;
+
+  @JSName('initWheelEvent')
+  void _initIEWheelEvent(
+      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
@@ -25533,6 +25714,23 @@ class EventStreamProvider<T extends Event> {
     return new _EventStream(e, _eventType, useCapture);
   }
 }
+
+typedef String _EventTypeGetter(EventTarget target);

[Siggi Cherem (dart-lang), 2013/01/16 18:52:00]

did you mean to use this type somewhere? (e.g. field of
_CustomEventStreamProvider?

[blois, 2013/01/16 20:04:02]

Yes, but dart2js checked mode issue blocked it. removed.

+
+/**
+ * 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.