Making ScriptProcessorNode not an EventTarget.

sdk/lib/web_audio/dart2js/web_audio_dart2js.dart

Index: sdk/lib/web_audio/dart2js/web_audio_dart2js.dart
diff --git a/sdk/lib/web_audio/dart2js/web_audio_dart2js.dart b/sdk/lib/web_audio/dart2js/web_audio_dart2js.dart
index 13d8b3645d7625c5fcef55be734e8ccd5602da34..269ca0692a505287290b068d747d0ad24bc07efd 100644
--- a/sdk/lib/web_audio/dart2js/web_audio_dart2js.dart
+++ b/sdk/lib/web_audio/dart2js/web_audio_dart2js.dart
@@ -4,7 +4,7 @@ import 'dart:async';
 import 'dart:collection';
 import 'dart:html';
 import 'dart:html_common';
-import 'dart:_js_helper' show Creates, Returns;
+import 'dart:_js_helper' show Creates, Returns, convertDartClosureToJS;
 import 'dart:_foreign_helper' show JS;
 // DO NOT EDIT - unless you are editing documentation as per:
 // https://code.google.com/p/dart/wiki/ContributingHTMLDocumentation
@@ -184,6 +184,9 @@ class AudioContext extends EventTarget native "*AudioContext" {
   @DocsEditable
   static const EventStreamProvider<Event> completeEvent = const EventStreamProvider<Event>('complete');
 
+  /// Checks if this type is supported on the current platform.
+  static bool get supported => JS('bool', '!!(window.AudioContex || window.webkitAudioContext)');
+
   @DomName('AudioContext.activeSourceCount')
   @DocsEditable
   final int activeSourceCount;
@@ -813,19 +816,145 @@ class PannerNode extends AudioNode native "*PannerNode" {
   @DocsEditable
   void setVelocity(num x, num y, num z) native;
 }
-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2013, 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.
 
 
-@DocsEditable
 @DomName('ScriptProcessorNode')
-class ScriptProcessorNode extends AudioNode implements EventTarget native "*ScriptProcessorNode" {
+class ScriptProcessorNode extends AudioNode native "*ScriptProcessorNode" {
+  Stream<AudioProcessingEvent> _eventStream;
+
+  /**
+   * Get a Stream that fires events when AudioProcessingEvents occur.
+   * This particular stream is special in that it only allows one listener to a
+   * given stream. Subsequent calls to [listen] after the first call will throw
+   */
+  Stream<AudioProcessingEvent> get onAudioProcess {
+    if (_eventStream == null) {
+      _eventStream = new _AudioEventStream(this);
+    }
+    return _eventStream;
+  }
 
   @DomName('ScriptProcessorNode.bufferSize')
   @DocsEditable
   final int bufferSize;
+
 }
+
+class _AudioEventStreamSubscription<AudioProcessingEvent> extends
+    StreamSubscription<AudioProcessingEvent> {
+  EventListener _callback;
+  ScriptProcessorNode _target;
+  bool _paused;
+
+  _AudioEventStreamSubscription(this._target, this._callback) {
+    _paused = false;
+    _tryResume();
+  }
+
+  void cancel() {
+    if (_callback != null) {
+      throw new StateError("Subscription has already been canceled.");
+    }
+    _unlisten();
+  }
+
+  void onData(void callback(AudioProcessingEvent)) {
+    if (_callback != null) {
+      throw new StateError("Subscription has been canceled.");
+    }
+    _setCallback(callback);
+  }
+
+  /// Has no effect.
+  void onError(void handleError(AsyncError error)) {}
+
+  /// Has no effect.
+  void onDone(void handleDone()) {}
+
+  void pause([Future resumeSignal]) {
+    if (_callback != null) {
+      throw new StateError("Subscription has been canceled.");
+    }
+    _unlisten();
+    _paused = true;
+
+    if (resumeSignal != null) {
+      resumeSignal.whenComplete(() { _paused = false; resume(); });
+    }
+  }
+
+  void resume() {
+    if (_callback != null) {
+      throw new StateError("Subscription has been canceled.");
+    }
+    if (!_paused) {
+      throw new StateError("Subscription is not paused.");
+    }
+    _tryResume();
+  }
+
+  void _tryResume() {
+    if (_callback != null) {
+      _setCallback(_callback);
+      _callback = null;
+    }
+  }
+
+  void _unlisten() {
+    if (_callback == null) {
+      var noop = (event) {};
+      _callback = JS('Function', '#.onaudioprocess', _target);
+      _setCallback(noop);
+    }
+  }
+
+  void _setCallback(callbackFunc) {
+    JS('void', '#.onaudioprocess = #', _target,
+        convertDartClosureToJS(_callback, 1));
+  }
+}
+
+/**
+ * Adapter for exposing DOM events as Dart streams.
+ */
+class _AudioEventStream<AudioProcessingEvent> 
+    extends Stream<AudioProcessingEvent> {
+  static Set _createdTargets = new Set();
+  ScriptProcessorNode _target;
+  StreamSubscription _streamSubscription;
+
+  _AudioEventStream(target) {
+    if (_createdTargets.contains(target)) {
+      throw new ArgumentError('This ScriptProcessorNode already has an event '
+          'stream associated with it. There can be only one listener per '
+          'ScriptProcessorNode');
+    } else {
+      _target = target;
+      _createdTargets.add(_target);
+    }
+  }
+
+  bool get isBroadcast => true;
+
+  StreamSubscription<AudioProcessingEvent> listen(
+      void onData(AudioProcessingEvent event),
+      { void onError(AsyncError error),
+      void onDone(),
+      bool unsubscribeOnError}) {
+    if (_streamSubscription != null) {
+      throw new StateError('Only one listener is allowed for this particular '
+          'stream.');
+    }
+    _streamSubscription = 
+        new _AudioEventStreamSubscription<AudioProcessingEvent>(
+            this._target, onData);
+    return _streamSubscription;
+  }
+}
+
 // 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.