Question

I have a custom UI drawn for my java application. Right now I draw the entire UI from scratch. I know for a fact some parts of the UI are static. I know I could save these static parts to an image, but will this yield a improvement in performance (Since even an image must be drawn every frame)?

Is it plausible to save a reference to the Graphics2D object after the UI has been drawn and assign that to the new graphics object every frame (starting from a point where all the static components are drawn)?

Thanks in advance,
Alan

Answer 1

You don’t need to redraw everything in every frame. So if you have static parts of your UI (or even dynamic parts that you know haven’t changed since last frame) then you simply don’t need to repaint them.

In my code (Swing games and simulations mostly) I usually try to follow the following rules:

1. Pre-prepare static images (e.g. BufferedImage textures for UI elements)
2. Override the paintComponent() method for each UI element individually to do the painting
3. Only call the repaint() method of any given UI element if I know that something has changed
4. Call repaint() in a timer-based loop for animation, but only call it on the portion of the UI that is being animated (e.g. a nested JPanel)

This approach seems to work and perform pretty well (though I’d welcome comments if there are ways to improve it!!)