[Java-gnome-developer] Assertion failure while drawing on DrawingArea

[Jaime <re...@sa...>]

Hi folks.

I've tried to write a simple little program to draw on a DrawingArea,
but without success. I get the following assertion failure at runtime:

(java-gnome:2393): Gdk-CRITICAL **: file gdkdraw.c: line 338
(gdk_draw_point): assertion `GDK_IS_DRAWABLE (drawable)' failed

Could anyone please tell me where I'm going wrong? In fact, a pointer to
any example code which successfully draws onto a DrawingArea would be
just as good! Thank you,

Jaime :-)


<snip>
package drawingAreaTest;

import org.gnu.gtk.DrawingArea;
import org.gnu.gtk.Gtk;
import org.gnu.gtk.Window;
import org.gnu.gtk.WindowType;
import org.gnu.gtk.event.ExposeEvent;
import org.gnu.gtk.event.ExposeListener;
import org.gnu.gtk.event.LifeCycleEvent;
import org.gnu.gtk.event.LifeCycleListener;

public class Test {

  DrawingArea area = null;

  Window window;

  Test() {
    window = new Window(WindowType.TOPLEVEL);
    window.setTitle("Drawing Area Example");
    window.addListener(new LifeCycleListener() {
      public void lifeCycleEvent(LifeCycleEvent event) {
      }
      public boolean lifeCycleQuery(LifeCycleEvent event) {
        if (event.isOfType(LifeCycleEvent.Type.DESTROY)
          || event.isOfType(LifeCycleEvent.Type.DELETE)) {
          Gtk.mainQuit();
        }
        return true;
      }
    });
    area=new DrawingArea();
    window.add(area);
    area.addListener(new ExposeListener() {
      public boolean exposeEvent(ExposeEvent event) {
        System.out.println("Expose event: "+window.getWindow());
        window.getWindow().drawPoint(20, 20);
        return false;
      }
    });
    window.showAll();
    System.out.println("Should be printed before expose event");
  }

  public static void main(String[] args) {
    Gtk.init(args);
    new Test();
    Gtk.main();
  }

}
</snip>