Building Kaffe with GTK AWT

Jim Pick jim at
Sun Apr 14 18:10:28 PDT 2002

On Fri, Apr 12, 2002 at 05:15:10PM +0200, Marc Haisenko wrote:
> Hi folks,
> 	I'm developing a STB using Linux on which we run a Java AWT app.

Cool.  I wouldn't mind talking to you about KaffePro then, since
that's looking like it's going to be our target market, primarily.
We're just in the initial stages of defining what we're going to do to
the product, and I wouldn't mind some feedback.

> Because of 
> space saving issues we'd like to get rid of X Window and use the framebuffer 
> instead. Now, GTK can be compiled to use the FB instead of X, and I've read 
> that Kaffe can be compiled to use GTK as the underlying layering for AWT, 
> thus making Kaffe able to run Java AWT apps on the framebuffer.

Transvirtual released a lightweight AWT called no-native-wm (plus a
framebuffer graphics library called fgl) with the PocketLinux stuff.
You can dig it out of the tarball here:

Of course, it's already somewhat dated and completely unsupported, and
don't expect Transvirtual to be updating or bugfixing it in the future
(although other people are free to build on top of the GPL'd code).

Now I'll plug my employer -- If you want something newer, and you
don't mind proprietary, Transvirtual is offering an updated, well
supported, proprietary framebuffer AWT + graphics library called XGL.
It runs on more JVMs than just KaffePro (eg. the ones from Sun, IBM).
There's some info about it on  Our graphics
department guys are working on acceleration support too.  I can put
you in touch with the right guys to talk to if you are interested.

In another email, there was mention of a free framebuffer AWT that
comes with Wonka.

Also, I know the Microwindows people got kaffe working with their
framebuffer library (I'm not sure if they used the Win32 widgets or
the X11 widgets as their base).

Does anybody know of any other free framebuffer AWT implementations?

There are some pretty cool base graphics libraries out there that look
nice (DirectFB, PicoGUI).  Some of those could be bound to
no-native-wm, I guess, but somebody would have to do the work.

There are some really small X servers that can be used.  Just to give
you an idea of how small the X protocol can be - I personally use
WeirdX (a X server written in Java) on my Windows laptop (I'm using it
to write this), and it's only 150k.  Of course, that doesn't handle
the underlying graphics primitives and fonts, just the X protocol, and
not many of the extensions.  The people have a cut-down
xfree86-based X server that runs on the iPAQ.  Running X is a little
extra overhead (say, 1MB, excluding fonts, which you need anyway), and
is a bit klunkier and slower to boot -- but it does give you a bit of
extra flexibility too.  A straight-to-the-framebuffer implementation
such as XGL probably weighs in at about 75k (excluding fonts), but
it's a little less flexible than X11, and all your native graphics
bits (eg. video players, Macromedia Flash players) need to be ported.
It's the standard type of tradeoff you get in embedded work - extra
development time up-front vs. extra production costs down the road.

> My problem is, I can't find any instructions on how to actually compile Kaffe 
> to use GTK instead of X. I've downloaded and untarred Kaffe 1.0.6 and 
> gtkawt.tar.gz, copied the content into the Kaffe source tree and am now 
> puzzled with how to go on. There seems to be no switch in the configure 
> script and there seems to be not a single document about this, not in the 
> source, not on the Kaffe web site and according to Google not on the net at 
> all.
> So, can somebody give me the needed hints ? Or is the GTK AWT dead ? If so, 
> does someone know of an alternative to get an AWT for the Linux framebuffer ?

I don't think anybody is using it.  I notice that there is also a GTK
AWT in the PocketLinux kaffe sources that were released.  It might be
same one...

I know the Trolltech guys are also selling a Qt AWT - I'm not sure if
it is available under the GPL or not.  Does anybody know?  Someday,
I'm going to phone them up and ask.  :-)

Classpath has a free AWT project too, but I think it's X11 only.  I
think Red Hat/Cygnus might also have been doing one, but I think they
are merging with Classpath now.

Once we get into full blown development mode, I'd like to collect as
many of the AWT implementations together as I can, and make them
selectable at configuration or run time.  I'm sure some of them are
going to be essentially "dead" (eg. BISS AWT), but there's no harm in
making them available.  The main one I'm going to support (for is going to be the X11 one, and maybe the Win32 one.
Perhaps we'll make the switch to the Classpath one if theirs turns out
to be better.


 - Jim

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