[vtkusers] Java app Xlib async problem

[Christopher.Moore at noaa.gov]

I know this was beaten to death, but I'm a humble C++ programmer trying to 
learn Java.

I'm using VTK 4.2 on RedHat 9, and I create a Java application, with a 
simple GUI, based on the Examples.  It uses vtkCanvas (which extends 
vtkPanel), so I thought I didn't have to worry about calls to the Renderer 
from the GUI, but I still get Xlib: unexpected async reply.

I'm including the shortest application I could make that repeats the 
problem.  Could someone let me know how I could fix the call to 
createIconFromScreen?  I tried using SwingUtilities.invokeLater, to no 
avail.

Thanks in advance,
Chris

==== code follows ====

import vtk.*;

import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;

/**
 *   Example application using Java-wrapped VTK
 *   to learn how to use threads in Java to avoid
 *   Xlib: async errors
 *
 *   Run the first time as is:
 *   (compile with "javac ExampleApp.java", run with "java ExampleApp")
 *
 *   Then uncomment the call to createIconFromScreen (line 128)
 *   and re-compile and run to see error message (click "Add" button
 *   repeatedly until error occurs)
 */

public class ExampleApp extends JFrame {

    private JToolBar mainTools;
    private JButton addButton;
    private JButton removeButton;
    private JButton cameraResetButton;
    private Dimension screenSize;

    private vtkCanvas renWin = null;
    private vtkRenderer ren = null;
    private vtkCamera camera = null;

    private Vector UserGobs = null;
    private int gobCount = -1;

    public ExampleApp() {
	this.setSize(800, 800);

	screenSize = Toolkit.getDefaultToolkit().getScreenSize();

	WindowListener l = new WindowAdapter() {
		public void windowClosing(WindowEvent e) {
		    System.exit(0);
		}
	    };
	this.addWindowListener(l);

	mainTools = new JToolBar();
	mainTools.setOrientation(1);

	addButton = new JButton("Add");
	addButton.addActionListener(new ActionListener() {
		public void actionPerformed(ActionEvent evt) {
		    addActor(evt);}
	    });
	mainTools.add(addButton);

	removeButton = new JButton("Remove");
	removeButton.addActionListener(new ActionListener() {
		public void actionPerformed(ActionEvent evt) {
		    removeActor(evt);}
	    });
	mainTools.add(removeButton);

	cameraResetButton = new JButton("ResetCamera");
	cameraResetButton.addActionListener(new ActionListener() {
		public void actionPerformed(ActionEvent evt) {
		    updateCamera();}
	    });
	mainTools.add(cameraResetButton);

	this.getContentPane().add(mainTools, BorderLayout.WEST);

	renWin = new vtkCanvas();

	// attach observer to set the render window size after
	// the render window is created...
	renWin.addWindowSetObserver(new Observer() {
		public void update(Observable o, Object arg) {
		    renWin.setSize(800, 800);
		}
	    });
	this.getContentPane().add(renWin, BorderLayout.CENTER);
	renWin.setSize(800,800);

	ren = renWin.GetRenderer();
        ren.SetBackground(1,1,1);
	ren.LightFollowCameraOn();

	this.getContentPane().add(renWin, BorderLayout.CENTER);

	// Always have at least one actor:
	vtkConeSource cs = new vtkConeSource();
	cs.SetRadius(0.5);
	cs.SetHeight(2.0);
	vtkPolyDataMapper coneMapper = new vtkPolyDataMapper();
	coneMapper.SetInput(cs.GetOutput());
	vtkActor coneActor = new vtkActor();
	coneActor.SetMapper(coneMapper);
	coneActor.GetProperty().SetColor(0,0,1);
	coneActor.AddPosition(0,1.0,0);
	ren.AddActor(coneActor);

	UserGobs = new Vector();

	camera = ren.GetActiveCamera();
    }


    private void updateCamera() {
	camera.SetPosition(0,0,10.0+(double)gobCount);
	camera.SetFocalPoint(0,0,0);
	camera.SetViewUp(0,1,0);
	renWin.resetCameraClippingRange();
	renWin.Render();
    }

    private void addActor(ActionEvent evt) {
	Hydro ctdHydro = new Hydro();
	UserGobs.add(ctdHydro);
	gobCount++;
	ctdHydro.getActor().GetProperty().SetColor(1,(double)gobCount/5.0,0);
	ctdHydro.getActor().AddPosition((double)gobCount/4.0,0,0);
	ren.AddActor(ctdHydro.getActor());
	renWin.resetCameraClippingRange();
	renWin.Render();
	// uncomment this to get Xlib: async error
	//createIconFromScreen();
    }

    private void removeActor(ActionEvent evt) {
	if (gobCount >= 0) {
	    Hydro ctdHydro = (Hydro) UserGobs.get(gobCount);
	    ren.RemoveActor(ctdHydro.getActor());
	    UserGobs.remove(gobCount);
	    gobCount--;
	    renWin.Render();
	}
    }

    public class Hydro {
	private vtkActor HydroActor;

	public Hydro() {
	    vtkSphereSource ss = new vtkSphereSource();
	    ss.SetRadius(1.0);
	    vtkPolyDataMapper sMapper = new vtkPolyDataMapper();
	    sMapper.SetInput(ss.GetOutput());
	    HydroActor = new vtkActor();
	    HydroActor.SetMapper(sMapper);
	}

	public vtkActor getActor() {
	    return HydroActor;
	}

    }

    private void createIconFromScreen() {
	// I tried with and without "invokeLater"
	SwingUtilities.invokeLater(new Runnable() {
		public void run() {
		    vtkWindowToImageFilter w2i = new vtkWindowToImageFilter();
		    w2i.SetInput(renWin.GetRenderWindow());
		    w2i.Update();

		    int[] dims = w2i.GetOutput().GetDimensions();
		    System.out.println("image x: " + dims[0]);
		    System.out.println("image y: " + dims[1]);
		    System.out.println("image z: " + dims[2]);
		}
	    });

	/*
	vtkPNGWriter pngWriter = new vtkPNGWriter();
	pgnWriter.SetInput(w2i.GetOutput());
	pngWriter.SetFileName();
	pngWriter.Write();

	w2i.Delete();
	pngWriter.Delete();
	*/
    }

    public static void main(String[] args) {
	JFrame f = new ExampleApp();
	f.pack();
	f.setVisible(true);
    }
}