Save graphics as image?

I'm developing an app for BlackBerry with Eclipse and want to know if there is any way to save a picture that is drawn with a Graphics object...The app involves drawing a pie chart using Graphics.It works fine the first time I open the screen to display the chart but the next time I try to create the chart by calling th开发者_C百科e screen, it goes haywire.So I was wondering if I can save the chart as an image...that way I wont have to keep drawing over and over everytime I open the screen...Please help...Thanks in advance!

I understood you are using the java.awt.Graphics class, right? Ensure you are drawing only on the AWT event thread. Use

SwingUtilities.invokeLater(new Runnable() {
  public void run() {
    // YOUR CODE        
  }
});

to run your saving code on the event thread. If you try to save from another thread, the image could get distorted if it is not drawn completely.

I don't know the blackberry API but you could take other aproach to your problem. You could do offscreen rendering. Create a BufferedImage, get a reference to its Graphics object, do the rendering and then save the BufferedImage as a png for example.

For example:

int width = 200, height = 200;

// TYPE_INT_ARGB specifies the image format: 8-bit RGBA packed
// into integer pixels
BufferedImage bi = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);

Graphics2D ig2 = bi.createGraphics();

// Draw your chart

ImageIO.write(bi, "PNG", new File("yourImageName.PNG"));

This way you can do all your drawing once, saving it as a file or just in memory (depends on what you need) and then you just need either to load the image from the file or do g.drawImage() in your screen.

But as i said before i don't know if this applies to the Blackberry API it works for sure with the JDK/JRE in a desktop.