Saving large images - Raster problem

I already asked a Question how to save large images and I think I'm on the right track but I still need some advice.

I have an Image 12000 x 12000 and I need to save it as .png

BufferedImage can't be used.

I was already advised to use the RenderedImage interface but somehow I can't get the desired result. ( I haven't worked with rasters yet so probably I got something wrong )

Code for the saving image method:

   public static void SavePanel() {

    PanelImage IMAGE = new PanelImage(panel);

    try {
        ImageIO.write(IMAGE, "png"开发者_JS百科, new File(ProjectNameTxt.getText() +  ".png"));
    } catch (IOException e) {
    }

   }

And code for the PanelImage class:

 public static class PanelImage implements RenderedImage {

    // some variables here

    public PanelImage(JImagePanel panel) {
       this.panel = panel;
    }

  public Raster getData(Rectangle rect) {

        sizex = (int) rect.getWidth();
        sizey += (int) rect.getHeight();
        image = null;
        image = new BufferedImage(
                (int) sizex,
                (int) sizey,
                BufferedImage.TYPE_INT_RGB);
        g2 = image.createGraphics();
        panel.paintComponent(g2);
        return image.getData();
    }

 // rest of the implemented methods - no problems here
 }

I noticed that the ImageIO requests one line of pixels at a time ( 12000 x 1 ). This method is working but I still need the whole image in the BufferedImage. I have to increase the size of the BImage each time ImageIO calls the method, otherwise I get " Coordinate out of bounds! " exeption

Thanks

This PNGJ library can be useful to read/write huge images, because it does it sequentially, it only keeps a line in memory at a time. (I wrote it myself a while ago, because I had a similar need)

I just hacked an minimal working example for a ComponentImage, which takes an arbitrary JComponent and can be passed to ImageIO for writing. For brevity, only the "interesting" parts are included here:

public final class ComponentImage implements RenderedImage {    
    private final JComponent comp;
    private final ColorModel colorModel;
    private final SampleModel sampleModel;

    public ComponentImage(JComponent comp) {
        this.comp = comp;
            this.colorModel = comp.getColorModel();
        this.sampleModel = this.colorModel.createCompatibleWritableRaster(1, 1).
                getSampleModel();
    }
    @Override
    public ColorModel getColorModel() {
        return this.comp.getColorModel();
    }

    @Override
    public SampleModel getSampleModel() {
        return this.sampleModel;
    }
    @Override
    public Raster getData(Rectangle rect) {
        final WritableRaster raster = this.colorModel.
                createCompatibleWritableRaster(rect.width, rect.height);

        final Raster result = raster.
                createChild(0, 0, rect.width, rect.height,
                rect.x, rect.y, null);

        final BufferedImage img = new BufferedImage(
                colorModel, raster, true, null);

        final Graphics2D g2d = img.createGraphics();
        g2d.translate(-rect.x, -rect.y);
        this.comp.paintAll(g2d);
        g2d.dispose();

        return result;

    }
}