This is what I effectively have today, but my point was that JSO's
can't subclass CanvasImpl. It is not the Canvas object that needs to
be a JSO, it's the CanvasImpl object, because it is the CanvasImpl
object that has the JSNI methods on it which directly interact with
the browser's native canvas.
Today, I have a wrapper for CanvasImpl, it looks sorta like this:
public class BrowserCanvasImpl extends CanvasImpl {
private JavaScriptObject ctx;
public native void moveTo(int x, int y) /*-{
[EMAIL PROTECTED]::ctx.moveTo(x,y);
}-*/;
}
What I really want is this:
public class BrowserCanvasImpl extends JavaScriptObject {
public native void moveTo(int x, int y) /*-{
this.moveTo(x,y);
}-*/;
}
public class FlashCanvasImpl extends JavaScriptObject {
public native void moveTo(int x, int y) /*-{
flashObject.drawCommand('m', x, y);
}-*/;
}
And the ability to bind either one of these based on deferred binding.
This returns the generated JavaScript output from:
foo.ctx.moveTo(x,y);
to
foo.moveTo(x,y); or foo.drawCommand('m', x,y);
Here's a question. What if CanvasImpl was a JSO with a bunch of stub
methods (non-final), and each subclass of CanvasImpl overrode every
stub method with a final method, would it still work? Actually, the
final isn't needed. In a sense, if due to a deferred binding, only a
single concrete subclass implementation exists, and no method dispatch
on CanvasImpl is ever polymorphic, then everything is "effectively"
final and it should work. Couldn't the JSO restriction checker be a
little more lenient and just prove in each permutation that no virtual
dispatches occur?
-Ray
On Fri, Aug 29, 2008 at 3:40 PM, Scott Blum <[EMAIL PROTECTED]> wrote:
> What about this?
> public final class Canvas extends JavaScriptObject {
> private static CanvasImpl impl = GWT.create(CanvasImpl.class);
> public static Canvas create() {
> return impl.create();
> }
> public void moveTo(int x, int y) {
> return impl.moveTo(this, x, y);
> }
> }
> Then you just create several subclasses of CanvasImpl, for Canvas, Flash,
> SVG, etc.
>
> >
>
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http://groups.google.com/group/Google-Web-Toolkit-Contributors
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