Added a rudimentary DOM, to assist with event dispatch.

runtime/embedders/openglui/common/gl.dart

Index: runtime/embedders/openglui/common/gl.dart
===================================================================
--- runtime/embedders/openglui/common/gl.dart	(revision 19252)
+++ runtime/embedders/openglui/common/gl.dart	(working copy)
@@ -4,7 +4,140 @@
 
 library android_extension;
 
-class CanvasElement {
+// A VERY simplified DOM.
+
+class BodyElement {
+  List _nodes;
+  get nodes => _nodes;
+  BodyElement() : _nodes = new List();
+}
+
+class HtmlDocument {

[vsm, 2013/03/04 17:34:55]

I'd rather make this "Document" ... but body is defined only HtmlDocument right
now.  Maybe a TODO to revisit?  It'd be nice not to have the name HTML anywhere.

[gram, 2013/03/04 23:53:14]

Changed to OpenGLUIDocument. As the user just uses the document singleton, that
should be fine.

+  BodyElement _body;
+  get body => _body;
+  HtmlDocument() : _body = new BodyElement();

[vsm, 2013/03/04 17:34:55]

Can we make these constructors (this and below) private?  I don't think the user
should ever be creating these.

[gram, 2013/03/04 23:53:14]

I'm familiar with doing this in Cxx/Java when implementing Singletons, but how
would you do that in Dart? 

[vsm, 2013/03/05 00:23:58]

The usual pattern is:
   HtmlDocument._internal() : ...;

and, below:
  new HtmlDocument._internal();

[gram, 2013/03/05 01:06:49]

Done.

+}
+
+HtmlDocument document = new HtmlDocument();
+
+// Event handling. This is very kludgy for now, especially the
+// bare-bones Stream stuff!
+
+class Event {
+  final String type;
+  Event(String type) : this.type = type;
+}
+
+class KeyEvent extends Event {
+  final bool altKey;
+  final bool ctrlKey;
+  final bool shiftKey;
+  final int keyCode;
+
+  KeyEvent(String type, int keycode, bool alt, bool ctrl, bool shift) 
+    : super(type),
+      keyCode = keycode,
+      altKey = alt,
+      ctrlKey = ctrl,
+      shiftKey = shift {
+  }
+}
+
+class MouseEvent extends Event {
+  final double screenX, screenY;
+  final double clientX, clientY;

[vsm, 2013/03/04 17:34:55]

These are ints, not doubles in dart:html.

[gram, 2013/03/04 23:53:14]

Done.

+
+  MouseEvent(String type, double x, double y)
+    : super(type),
+      screenX = x,
+      screenY = y,
+      clientX = x,
+      clientY = y {
+  }
+}
+
+class StreamSubscription {
+  Stream _stream;
+  int _id;
+
+  StreamSubscription(this._stream, this._id);
+  void onData(handler) => _stream.onData(_id, handler);

[vsm, 2013/03/04 17:34:55]

Probably should declare:
typedef void EventListener(Event event)

and just use this type for handler.

[gram, 2013/03/04 23:53:14]

Done.

+}
+
+class Stream {

[vsm, 2013/03/04 17:34:55]

These will conflict with the names in dart:async.  We should be able to use that
library alongside ours.

[gram, 2013/03/04 23:53:14]

Modified the code to work with async library.

+  int _nextListenerId;
+  Map _listeners;
+
+  Stream() : _nextListenerId = 0, _listeners = new Map();
+
+  void onData(id, handler) {

[vsm, 2013/03/04 17:34:55]

types for args

[gram, 2013/03/04 23:53:14]

Done.

+    _listeners[id] = handler;
+  }
+
+  listen(callback) {

[vsm, 2013/03/04 17:34:55]

types for args

[gram, 2013/03/04 23:53:14]

Done.

+    var sub = new StreamSubscription(this, _nextListenerId++);
+    sub.onData(callback);
+    return sub;
+  }
+
+  post(Event e) {
+    for (var listener in _listeners.values) {
+      listener(e);
+    }
+  }
+}
+
+class Node {
+  Map<String,Stream>  _events;
+
+  get onMouseDown => _events['mousedown'];
+  get onMouseMove => _events['mousemove'];
+  get onMouseUp => _events['mouseup'];
+  get onKeyDown => _events['keydown'];
+  get onKeyUp => _events['keyup'];
+
+  get events => _events;
+
+  Node() : _events = new Map() {
+    _events['mousedown'] = new Stream();
+    _events['mousemove'] = new Stream();
+    _events['mouseup'] = new Stream();
+    _events['keydown'] = new Stream();
+    _events['keyup'] = new Stream();
+  }
+}
+
+_dispatchEvent(String type, Event e) {
+  for (var n in document.body.nodes) {
+    var handler = n.events[type];
+    if (handler != null) {
+      handler.post(e);
+    }
+  }
+}
+
+_dispatchKeyEvent(String type, int keyCode, bool alt, bool ctrl, bool shift) =>
+    _dispatchEvent(type, new KeyEvent(type, keyCode, alt, ctrl, shift));
+
+_dispatchMouseEvent(String type, double x, double y) =>
+    _dispatchEvent(type, new MouseEvent(type, x, y));
+
+onKeyDown(int when, int keyCode, bool alt, bool ctrl, bool shift, int repeat)

[vsm, 2013/03/04 17:34:55]

Do you really want these to be globally visible?  (Instead of _onKeyDown?)

[gram, 2013/03/04 23:53:14]

They have to be callable from vmglue.cc. Would they work if they were private?

[vsm, 2013/03/05 00:23:58]

I'm pretty sure it will work fine.  Dartium does it for creating Dart DOM nodes.

On 2013/03/04 23:53:14, gram wrote:

[gram, 2013/03/05 01:06:49]

I tried, but it didn't work:

Invoke _onMouseDown failed: Dart_Invoke: did not find top-level function
'_onMouseDown'.

I've changed the names to something less likely to result in a collision by
adding an underscore on the end instead.

+    =>  _dispatchKeyEvent('keydown', keyCode, alt, ctrl, shift);
+
+onKeyUp(int when, int keyCode, bool alt, bool ctrl, bool shift, int repeat) =>
+    _dispatchKeyEvent('keyup', keyCode, alt, ctrl, shift);
+
+onMouseDown(int when, double x, double y) =>
+    _dispatchMouseEvent('mousedown', x, y);
+
+onMouseMove(int when, double x, double y) =>
+    _dispatchMouseEvent('mousemove', x, y);
+
+onMouseUp(int when, double x, double y) =>
+    _dispatchMouseEvent('mouseup', x, y);
+
+class CanvasElement extends Node {
   int _height;
   int _width;
 
@@ -19,7 +152,8 @@
   // code.
   get src => "context2d://${_context2d.handle}";
 
-  CanvasElement({int width, int height}) {
+  CanvasElement({int width, int height})

[vsm, 2013/03/04 17:34:55]

Can we have more than one Canvas right now?

[gram, 2013/03/04 23:53:14]

Yes. Currently we can have just one canvas that is bound to the physical display
(this is the first canvas), but we can have multiple memory-backed canvases.

+    : super() {
     _width = (width == null) ? getDeviceScreenWidth() : width;
     _height = (height == null) ? getDeviceScreenHeight() : height;
   }