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Custom JComponent with embedded Swing components not positioned in exported image.

Answer 1

A:

Do you by any change modify the Transform object of the provided Graphics object in your custom Component? If you do make sure to save it first and then modify a new instance for your purposes and when you are done, set the old Transform back.

Savvas Dalkitsis 2010-08-26 21:28:09

No, i don't. The custom JComponents have just painted themselves on the graphics context of the new image. they did (do) all of the low-level positioning of bits themselves using the Rectangle passed in.

redBeard 2010-08-26 21:37:56

Answer 2

A:

I would try invoking the paint() method, not paintComponents().

Maybe because you are setting the text of the editor pane the text hasn't been properly parsed and the Document isn't in a final state when you attempt to paint the component. Or maybe because you are dynamically setting the bounds of components you have problems. Try wrapping the super.paint() method in a SwingUtilities.invokeLater().

The ScreenImage class is what I use to create images. But I've always used it to create images of static GUI's. That is I don't alter the bounds of components at the same time a try to create an image.

camickr 2010-08-27 02:42:15

Hmmm, didn't work. Same results.....

redBeard 2010-08-27 16:26:50

Answer 3

A:

Layout of Swing components usually occurs lazily rather than immediately so that might be causing your intermittent behaviour. You could try calling scrollPane.doLayout() directly - usually this is a bad idea but it should guarantee that scrollPane is laid out before you paint it.

Also for painting to an off-screen image you should probably call printAll(g) rather than paintComponents(g) as that avoids double buffering issues.

Russ Hayward 2010-08-27 09:14:06

Hmm, no changes. same results....

redBeard 2010-08-27 16:28:29

Answer 4

A:

Found a solution!! Your comments about 'scheduling painting events' rang around in my head for a bit. I had a problem like this some years ago and forgot about that. Old age will do that....

The solution is to wrap the 'draw()' method in a 'SwingUtilities.invokeAndWait()'. Voila! My 'export()' method now looks like:

    public void export(File file, final int width, final int height)
    throws IOException
{

    BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
    final Graphics2D g2 = image.createGraphics();

    //  Must wait for the bloody image to be drawn as Swing 'paint()' methods
    //  merely schedule painting events.  The 'draw()' below may not complete
    //  the painting process before the 'write()' of the image is performed.

    //  thus, we wait....

    try {
        SwingUtilities.invokeAndWait(new Runnable() {
            public void run() {
                draw (g2, new Rectangle (0, 0, width, height));
            }
        });
        ImageIO.write(image, "png", file);
    } catch (FileNotFoundException e) {
        throw new IOException ("Unable to export chart to ("
                + file.getAbsolutePath() + "): " + e.getLocalizedMessage());
    } catch (InterruptedException e) {
        e.printStackTrace();
        throw new IOException ("Unable to export chart to ("
                + file.getAbsolutePath() + "): " + e.getLocalizedMessage());
    } catch (InvocationTargetException e) {
        e.printStackTrace();
        throw new IOException ("Unable to export chart to ("
                + file.getAbsolutePath() + "): " + e.getLocalizedMessage());
    } finally {
        g2.dispose();
    }
}

Whew!

redBeard 2010-08-27 17:03:42

That will hang the GUI if called on the EDT! Which makes me think the issue is really that the export code is calling paint on a non-EDT thread. Probably, somewhere deep in the bowels of Swing, some method determined it was not on the EDT and make an invokeLater call, thereby deferring the actual painting.

Devon_C_Miller 2010-08-31 16:39:19

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Custom JComponent with embedded Swing components not positioned in exported image.

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