Re: javafx

[Chris Vine <chris at cvine dot freeserve dot co dot uk>]

On Sat, 13 May 2017 09:30:35 -0700
Per Bothner <per@bothner.com> wrote:
> On 05/13/2017 05:58 AM, Chris Vine wrote:
> > There seems to be a problem with the 'javafx-scene' macro in
> > kawa-2.4.
> > 
> > First, the example at
> > https://www.gnu.org/software/kawa/Building-JavaFX-applications.html#idm139760384873792
> > fails to size the button correctly when compared with kawa-2.1.9.
> > The same occurs with kawa-2.3 (I have not tested with kawa-2.2).  
> 
> This was a bug introduced here:
> 
> 2016-06-26  Per Bothner  <per@bothner.com>
> 
> 	* MakeScene.scm (MakeScene): Don't create Group until
> actually needed.
> 
> I checked in a fix, in both the master and kawa-2.4 branches.
>   
> > kawa-2.3 works correctly (the buttons are correctly sized), whereas
> > kawa-2.4 fails to run the code, with this error:
> > 
> > Exception in Application start method
> > java.lang.RuntimeException: Exception in Application start method
> > 	at
> > com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
> > at
> > com.sun.javafx.application.LauncherImpl.lambda$launchApplication$156(LauncherImpl.java:182)
> > at java.lang.Thread.run(Thread.java:745) Caused by:
> > java.lang.ClassCastException: java.util.ArrayList cannot be cast to
> > javafx.scene.Node at
> > gnu.kawa.javafx.MakeScene.build(MakeScene.scm:54) at
> > javafx-test2.run(javafx-test2.kawa:10008) at
> > gnu.kawa.javafx.KawaJavafxApplication.start(defs.scm:65) at
> > com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$163(LauncherImpl.java:863)
> > at
> > com.sun.javafx.application.PlatformImpl.lambda$runAndWait$176(PlatformImpl.java:326)
> > at
> > com.sun.javafx.application.PlatformImpl.lambda$null$174(PlatformImpl.java:295)
> > at java.security.AccessController.doPrivileged(Native Method) at
> > com.sun.javafx.application.PlatformImpl.lambda$runLater$175(PlatformImpl.java:294)
> > at
> > com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
> > at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method) at
> > com.sun.glass.ui.gtk.GtkApplication.lambda$null$50(GtkApplication.java:139) ...
> > 1 more  
> 
> I was able to reproduce it before, though only on the old 2.4 branch.
> It seems to have gone away - though it might be JDK or other
> environment issues. Let me know if you still experience it with the
> kawa-2.4 branch. Of course, you could also switch to the master
> (formerly 'invoke') branch; I doubt I'll make another 2.4.x release.

I posted this mainly to alert you to the issue rather than needing a
fix myself, as I use your binary distribution.  Congratulations on the
job you have done with kawa: I find that programming Java is not a
pleasant experience (its like being in an Austin Powers time warp), so
it is good to have something nice to program for on the JVM.

As regards javafx I prefer to reproduce the kawa definition of
javafx-application (which also injects javafx-stage) and
KawaJavafxApplication directly into a separate importable file and build
the scene myself rather than use the javafx-scene macro.

Apart from anything else, javafx-defs aliases a random set of other
definitions such as Button, Node and FlowPane which can clash with the
user code's own imports (if any) and I find it easier to avoid
javafx-scene altogether.  But I came across the problem and thought I
would let you know.

Chris