Hey Jake,

I've never used the SWT Canvas, but if it's anything like the <canvas>
tag, you might want to check out the GWTCanvas in the incubator:
http://code.google.com/docreader/#p=google-web-toolkit-incubator&s=google-web-toolkit-incubator&t=GWTCanvas


Also, Vitali, there's a GWT library for accessing gears:
http://code.google.com/p/gwt-google-apis/

Regards,
--
Arthur Kalmenson



On Tue, Apr 7, 2009 at 3:35 PM, Jake <[email protected]> wrote:
>
> Isaac, thank you for the informed response, I believe that was exactly
> what I was looking for.
>
> Best regards,
>
> Jake
>
> On Apr 7, 3:27 pm, Isaac Truett <[email protected]> wrote:
>> Jake,
>>
>> You would have to create a class org.eclipse.swt.widgets.Canvas such
>> that it is GWT-compatible. That means only using emulated JRE classes
>> (String, collections, etc.). Any class required for the Canvas class
>> API has to be implemented in a GWT-compatible manner as well. This
>> transitive dependency is what really kills you. If you get to a point
>> where you have to use a non-emulated JRE class (e.g., java.io.*
>> (almost)), you're hosed (I believe this was essentially Ian's point).
>>
>> Assuming you manage to implement the entire API, you create a module
>> file (gwt.xml) that includes the source you just wrote, inherit that
>> module in your GWT app, and enjoy.
>>
>> For more on JRE emulation, see:
>>
>> http://code.google.com/docreader/#p=google-web-toolkit-doc-1-5&s=goog...
>>
>> - Isaac
>>
>> On Tue, Apr 7, 2009 at 3:14 PM, Jake <[email protected]> wrote:
>>
>> > I feel like I'm not expressing myself clearly. Let's just focus on the
>> > reduced case:
>>
>> > import org.eclipse.swt.widgets.Canvas;
>>
>> > public class foo {
>>
>> > }
>>
>> > Right now, if I try to run this through GWT, it will throw an error
>> > because it can't compile Canvas and all of its dependencies. This is
>> > to be expected. So what I would like is to roll my own Canvas class
>> > which extends GWT's Widget class, and have that be used instead, but
>> > in such a way that I don't have to touch the existing program's source
>> > code.
>>
>> > Ian, you seem to be suggesting that I need to hack this into the
>> > internals of GWT itself, and try to push it upstream. I feel like
>> > there should be a way to do this without having modify GWT internals,
>> > because this would allow certain applications (not all of them) that
>> > leverage native GUI toolkits to be compiled directly to a browser-
>> > based version, without having to port them to a GWT-friendly set of
>> > libraries. This would be a very powerful feature, but it may not
>> > exist. If I could just get confirmation on this, I would appreciate
>> > it.
>>
>> > Thanks,
>>
>> > Jake
>>
>> > On Apr 7, 2:38 pm, Ian Bambury <[email protected]> wrote:
>> >> GWT isn't Java. It just uses Java syntax so that Java books are useful, 
>> >> and
>> >> things like Eclipse work for it.
>> >> GWT code becomes JavaScript. It is never at any point Java.
>>
>> >> A very simple compiler might recognise '"Window.alert(" and translate it 
>> >> to
>> >> '"document.alert("
>>
>> >> If you whole program consists of Window.alert("Hello"); then it will be 
>> >> OK.
>> >> Anything else will fail.
>>
>> >> The Google team have emulated many other commands and structures, but not
>> >> all of them: some are obscure and therefore not high enough up the 
>> >> priority
>> >> list, and some are impossible because, like threading, JS just doesn't do
>> >> that.
>>
>> >> It would be an impossible task to emulate every possible class in every 
>> >> Java
>> >> library in existence. And would take for ever.
>>
>> >> So if it ain't emulated, it ain't gonna work because the compiler will 
>> >> issue
>> >> a polite and rather technical version of 'WTF?'
>>
>> >> And just throwing any old java program into the GWT compiler is, pretty
>> >> much, pointless.
>>
>> >> But if you really want to help Google and emulate 
>> >> rg.eclipse.swt.widgets.Canvas
>> >> for GWT, then I'm sure they (and many others) will be eternally grateful 
>> >> for
>> >> at least a week or two :-)
>>
>> >> If so, troll your little old lallies over to the very 
>> >> bonahttp://groups.google.com/group/Google-Web-Toolkit-Contributors
> >
>

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