Code

private void testPngExport()
{
	double dpiScale = 4;
	double unitScale = Utilities.convert(
		1, diagram.getMeasureUnit(), GraphicsUnit.Point);
	double scale = unitScale * dpiScale;

	// create bitmap image
	BufferedImage img = new BufferedImage(
		(int)(diagram.getBounds().getWidth() * scale),
		(int)(diagram.getBounds().getHeight() * scale),
		BufferedImage.TYPE_INT_ARGB);

	// draw the diagram
	Graphics2D graphics = img.createGraphics();
	graphics.scale(scale, scale);
	diagram.draw(
		graphics,
		new RenderOptions(),
		diagram.getBounds());

	File file = new File("test.png");
	try
	{
		ImageIO.write(img, "png", file);
	}
	catch (IOException e)
	{
		// TODO Auto-generated catch block
		e.printStackTrace();
	}
}