java jpanel synchronization with repaint() or: Is a Listener addable to swing's repaint?

Question

I'm writing a plugin for a miscropy program and have problems with the repaint() method.

short question: Is there any way to get informed as soon as the repaint of a JPanel was done or synchronize the code with it?

detailed version:

My program can plot a set of data in a xy-chart to a JPanel and show it using jfree.chart; In another part of the programm I have many datasets (~100) that I want to plot and save as images. I've also found a solution, but I really don't like it. The Problem can be reduced to a notification about the paint status of a JPanel.

In the part that shall save all images I have this solution:

PlotSpectrum spectrumWindow = getTheWindow(); //pseudo code...
// some stuff
ti = storage.getImage(channel, slice, frame, position);
spectrumWindow.plotData(false, andor.captureSpectrum(ti.pix), wave,
                 centerWave, fineGrating, exposureTime,
                 slitWidth, substractBackground);
spectrumWindow.repaint(); // probably not necessary
sleep(100);               // this annoys me...
spectrumWindow.savePlot(path, true, config, null);

spectrumWindow is a JPanel that is also displayed in another window and it all works fine. BUT I really don't like that sleep(100) in there... without it I'm asking for a repaint but it isn't done till I try to save a "snapshot" of (thats what savePlot is doing...). I know, other Thread and these damn synchronization problems... With the sleeping I'm just making it unnecessary slow and if I wait not long enough the images are not completly drawn (eg lower half missing)

Is there any way to get informed as soon as the repaint was done? I probably would be also fine with a Listener, better would be a solution with a monitor or sth comparable or a method that is repainting NOW (doesn't exists as far I know?) The main GUI (include the JPanel spectrumWindow) and the earlier pasted code are running in different Threads.

The probably also important parts of my code are following here. Please excuse if some brackets aren't matching or some variables aren't declared, I removed very much code.

thanks schetefan24

class PlotSpectrum extends ApplicationFrame // that extends JFrame
{
public void plotData(boolean backgroundGiven, int[] spect, double[] wave_,
                     double centerWave, boolean fineGrating_, double exposureTime,
                     double slitWidth, boolean substractBackground)
{
//process data and store internally
replot();
}

private void replot()
{
XYSeries series = new XYSeries("Spectrum");
//add data to series
XYSeriesCollection collection = new XYSeriesCollection(series);
//setting up some labels and such stuff...
 JFreeChart chart = ChartFactory.createXYLineChart(
        title,
        "Wavelength [nm]", 
        yLabel, 
        collection,
        PlotOrientation.VERTICAL,
        false,
        false,
        false
    );
 dataPanel.add(new ChartPanel(chart)); // this is contained in a Frame
}

public void savePlot(String path, boolean overWriteAll, HashMap<String,String> config, int[][] addData)
{
File output = new File(path);
//some more stuff, ask overwrite etc
if(image)
{
    BufferedImage im = createImage();
    String extension = path.substring(path.lastIndexOf(".")+1, path.length());
    ImageIO.write(im, extension, output);
} else {
//that is an textexport, works fine
}
}

public BufferedImage createImage()
{
    JPanel panel = (JPanel) flipChart.getSelectedComponent();
    int w = panel.getWidth();
    int h = panel.getHeight();
    BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
    Graphics2D g = bi.createGraphics();
    panel.paint(g);
    return bi;
}
}

Answer 1

that I want to plot and save as images.

1. add the data to a non visible panel.
2. create a BufferedImage of the panel
3. create an ImageIcon using the Image from above
4. update a JLabel (that has already been added to the frame) using the setIcon(...) method
5. the above step should generate a PropertyChange event when the Icon changes. You can use a ProperChangeListener to listen for this event. When you receive the event you can repeat steps 1 - 4.

Check out Screen Image. It will help you create an image of a non-visible component.

Note, you don't really need steps 4-5. I just added them so you have a visual of the plots as they are being processed. If you don't want the visual then maybe you just display text on a JLabel indicating which plot is currently being converted.