Re: extended peers

[Dalibor Topic]

Hallo Sascha,

Sascha Brawer wrote:
> graydon hoare <address@hidden> wrote on Wed, 10 Sep 2003 01:36:53 -0400:
>
>
> > I would like to attach some extra methods to a singleton object of
> > some sort -- something like Toolkit or GraphicsEnvironment, or a
> > classpath-specific subclass of these -- to produce peer or peer-like
> > (native-assisted subclass) objects for use in java2d.
>
>
> I think this is an excellent idea. I guess it comes to the following:
>
> - gnu.java.awt.peer -- abstract, platform-independent classes
> - gnu.java.awt.peer.gtk -- your GTK/Cairo implementation
> - gnu.java.awt.peer.(xxx) -- other implementations
>
> package gnu.java.awt.peer;
> abstract class GeneralGraphicsEnvironment
>   // should this be "ClasspathGraphicsEnvironment"?
>   // "CPGraphicsEnvironment"? "GNUGraphicsEnvironment"?
>   extends java.awt.GraphicsEnvironment
> {
>   abstract GeneralFontPeer createFontPeer(java.awt.Font awtFont, double
> size, ...);
> }
>
> package gnu.java.awt.peer.foo;
> class FooGraphicsEnvironment
>   extends gnu.java.awt.peer.GeneralGraphicsEnvironment
> {
>   GeneralFontPeer createFontPeer(...) { return new FooFontPeer(...); }
> }
>
> By the way, there are now some GDK/GTK-related classes in
> gnu.java.awt.image. Could/should these move to gnu.java.awt.peer.gtk as well?
>
> How will methods like java.awt.GraphicsEnvironment.getLocalEnvironment()
> know about the right peers?

What about having Classpath Graphics Environments that support the font 
peer factory interface imlement such an interface?

package gnu.java.awt.peer;

/* Here goes documentation about the FontPeerFactory interface */
public interface FontPeerFactory {
        GeneralFontPeer createFontPeer(java.awt.Font awtFont, double size, ...);
}

import gnu.java.awt.peer.FontPeerFactory;

package gnu.java.awt.peer;
abstract class GeneralGraphicsEnvironment
   // should this be "ClasspathGraphicsEnvironment"?
   // "CPGraphicsEnvironment"? "GNUGraphicsEnvironment"?
   extends java.awt.GraphicsEnvironment
   implements FontPeerFactory
 {
 }

Then getLocalEnvironment() could check if a GraphicsEnvironment 
instanceof FontPeerFactory.

cheers,
dalibor topic