Is there any better way to refresh?

Question

Hello
I would like to know if anyone here has a better solution for refreshing components like JPanels. I'm developing an application which uses slow algorithms to draw the points on them. It would be absurd to call these methods again to simply refresh these components (ex: when the user minimizes or resizes the component), just as absurd as it would be to put the slow algorithm code in the paint(Graphics g) method.
The solution I'm using now is to save the coordinates and attributes of the points the program needs to draw in an array or some other data structure, so that the program can easily call a refresh method (which draws the points from the information store in these arrays).
But, since I'm using many (slow) algorithms, and since each plot has it's own particularities, I end up creating big refresh methods, even creating classes specifically to refresh components!
I was wondering if it would be possible to simply copy the image of a component in a given time, so that I could just repaint it on the component whenever it's necessary (i.e, when the component listeners called it). Is it possible?

Answer 1

I think want you're wanting to do is just a simple double-buffering?
So, the first time your component is asked to paint itself (you should override paintComponent() rather than paint(), by the way), do this:   private BufferedImage image = null;
   public void paintComponent(Graphics g) {
      if (image == null)
         image = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_RGB);
         Graphics imageG = image.createGraphics();
         // TODO: paint your component onto 'imageG'
      g.drawImage(imageG, 0, 0, null);
   }You may also want to reset 'image' to null if the component changes sizes.