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Re: Lightweight peer implementation



On Saturday, Aug 9, 2003, at 15:27 Pacific/Auckland, Thomas Fitzsimmons wrote:


On Fri, 2003-08-08 at 15:38, Scott Gilbertson Onsite wrote:
I claim that lightweights are not platform-specific, which is why I
submitted the following patch (which has not been comitted) a while back.
http://gcc.gnu.org/ml/java-patches/2003-q2/msg00140.html

Yup, I agree. Lightweights should be implemented entirely in the "generic" part of the code, not in the peer code.


I've adopted your approach and implemented some of the ComponentPeer
methods.  I tried to copy the behaviour of the corresponding Component
calls when peer == null.  My rational is that maybe we can eventually
remove the peer != null checks in Component.java, and assume that a
component always has a non-null peer, whether it be lightweight or
heavyweight.

I think the null peer checks in Component are required because the peers do not get created until the component is added to a container.


In the original thread, Tom mentioned that returning a gnu.java.awt
class from a java.awt class might not be a good idea.  What about
implementing LightweightPeer as a private inner class of
Component.java?  This approach would have the advantage that the peer
would have direct access to Component's fields.

I don't see a problem with returning a gnu.* class from getPeer(). Sun calls it sun.awt.NullComponentPeer (obtained via getPeer().getClass()) so our name is analogous to that. Having direct access to the fields would be nice (note that they are package-private), the problem of course is that clients can override the get/set methods, and matching the JREs behaviour with regard to what public methods it calls at what times might be important to some (badly written) applications. Does anyone have an idea on how much this matters in the real world?


Regards

Bryce.


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