1. High Performance Java Swing Animation David Wallace Croft 2004-05-22 Presented to the Plano Java Users Group Plano, TX Copyright 2004 David Wallace Croft. This work is licensed under the Creative Commons Attribution License.

2. David Wallace Croft ● Founder and VP, Game Developers Java Users Group (www.GameJUG.org) ● Taught Java game programming at the Institute of Interactive Arts & Engineering at UTD ● Author of "Advanced Java Game Programming" (www.CroftSoft.com/library/books/ajgp/) ● Software Developer, NIST ATP "Peer-to- Peer Virtual Reality Learning Environments" research grant project, Whoola Inc.

3. Open Source ● All code presented today is Open Source ● Code documented in detail in the book "Advanced Java Game Programming" ● Source code available for download from www.CroftSoft.com/library/books/ajgp/ ● Public Domain multimedia files also available ● This presentation archived on CroftSoft website

4. Performance Issues ● Clock resolution ● Hardware acceleration ● Repaint algorithm

5. Clock Resolution ● Need at least 24 fps for smooth animation ● Period of less than 42 ms ● System.currentTimeMillis() ● Clock resolution 50 to 60 ms on some Windows ● Swing Timer class limited to 20 fps ● Possibly due to clock resolution? ● Thread.sleep() within loop finer control

6. Animation Loop ● Phase 1: update sprite positions ● Phase 2: repaint sprites at new positions ● Phase 3: delay

7. LoopGovernor ● Slows animation loop down to desired frame rate ● Too slow = jerky animation ● Too fast = faster than monitor refresh, 100% CPU Do not squander time, for that is the stuff life is made of. -- Benjamin Franklin ● FixedDelayLoopGovernor ● SamplerLoopGovernor ● WindowedLoopGovernor

8. Hardware Acceleration ● Hardware acceleration for images ● Added to Java in version 1.4 ● Big difference in performance

9. Definitions ● VRAM = Video Random Access Memory ● Blit = BLT = Block Line Transfer ● Buffer = block of memory for image data ● Pixel = picture element ● Render = calculate and store pixel data ● Primary surface = screen surface ● Back buffer = offscreen image

10. Class Image ● Package java.awt ● Holds pixel (picture element) data ● Abstract superclass ● Subclasses – BufferedImage – VolatileImage

11. BufferedImage ● Quick and easy to modify pixel data ● Pixel data not in video memory ● Slow to transfer to video memory ● Blitting ● No hardware acceleration for drawing ops

12. VolatileImage ● Component.createVolatileImage(width,height ) ● Pixel data in video memory (VRAM) ● Hardware acceleration for drawing ops ● Video memory is volatile ● Screen saver will invalidate ● Must check and reload ● boolean VolatileImage.contentsLost()

13. CompatibleImage ● GraphicsConfiguration.createCompatibleIma ge() ● Pixel format conversion not needed ● BufferedImage for pixel manipulation ● VolatileImage cache for fast blitting ● Caching mechanism validates volatile memory ● Best for static images since cached ● Caching algorithm out of your control

14. Transparency ● GraphicsConfiguration.createCompatibleIma ge ( width, height, transparency ) ● Transparency.OPAQUE ● Transparency.BITMASK ● Transparency.TRANSLUCENT ● TRANSLUCENT not accelerated so slow ● Transparency lost when copying to VolatileImage

15. Translucent Demo ● SpriteDemo fog option ● Performance drops

16. Scaled BLT ● Graphics.drawImage ( x, y, width, height, null ) ● Slow ● Solution = pre-scale

17. loadAutomaticImage() ● com.croftsoft.core.awt.image.ImageLib ● Source code review

18. Repaint Algorithm ● Default algorithm in Swing bad for animation ● Creates union of dirty rectangles ● Slows down when rectangles far apart ● Demonstration using Sprite

19. RepaintCollector ● Phase 1: Collects repaint requests ● Phase 2: Delivers repaint requests ● Coalesces requests for efficiency ● Default algorithm in Swing bad for animation ● SimpleRepaintCollector ● BooleanRepaintCollector ● CoalescingRepaintCollector

20. References ● Jeffrey Kesselman, Understanding the AWT Image Types ● Michael Martak, Full-Screen Exclusive Mode API ● Sun, High Performance Graphics ● Sun, The VolatileImage API User Guide

21. Questions? ● Also ask via book discussion mailing list