Transcript www.croftsoft.com

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.
David Wallace Croft
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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"
Open Source
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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
Performance Issues
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Clock resolution
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Hardware acceleration
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Repaint algorithm
Clock Resolution
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Need at least 24 fps for smooth animation
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Period of less than 42 ms
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System.currentTimeMillis()
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Clock resolution 50 to 60 ms on some
Windows
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Swing Timer class limited to 20 fps
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Possibly due to clock resolution?
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Thread.sleep() within loop finer control
Animation Loop
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Phase 1: update sprite positions
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Phase 2: repaint sprites at new positions
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Phase 3: delay
LoopGovernor
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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
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FixedDelayLoopGovernor
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SamplerLoopGovernor
Hardware Acceleration
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Hardware acceleration for images
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Added to Java in version 1.4
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Big difference in performance
Definitions
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VRAM = Video Random Access Memory
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Blit = BLT = Block Line Transfer
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Buffer = block of memory for image data
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Pixel = picture element
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Render = calculate and store pixel data
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Primary surface = screen surface
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Back buffer = offscreen image
Class Image
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Package java.awt
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Holds pixel (picture element) data
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Abstract superclass
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Subclasses
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BufferedImage
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VolatileImage
BufferedImage
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Quick and easy to modify pixel data
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Pixel data not in video memory
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Slow to transfer to video memory
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Blitting
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No hardware acceleration for drawing ops
VolatileImage
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Component.createVolatileImage(width,height
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Pixel data in video memory (VRAM)
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Hardware acceleration for drawing ops
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Video memory is volatile
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Screen saver will invalidate
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Must check and reload
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boolean VolatileImage.contentsLost()
CompatibleImage
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GraphicsConfiguration.createCompatibleIma
ge()
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Pixel format conversion not needed
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BufferedImage for pixel manipulation
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VolatileImage cache for fast blitting
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Caching mechanism validates volatile
memory
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Best for static images since cached
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Caching algorithm out of your control
Transparency
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GraphicsConfiguration.createCompatibleIma
ge (
width, height, transparency )
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Transparency.OPAQUE
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Transparency.BITMASK
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Transparency.TRANSLUCENT
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TRANSLUCENT not accelerated so slow
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Transparency lost when copying to
VolatileImage
Translucent Demo
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SpriteDemo fog option
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Performance drops
Scaled BLT
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Graphics.drawImage ( x, y, width, height, null
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Slow
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Solution = pre-scale
loadAutomaticImage()
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com.croftsoft.core.awt.image.ImageLib
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Source code review
Repaint Algorithm
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Default algorithm in Swing bad for animation
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Creates union of dirty rectangles
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Slows down when rectangles far apart
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Demonstration using Sprite
RepaintCollector
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Phase 1: Collects repaint requests
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Phase 2: Delivers repaint requests
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Coalesces requests for efficiency
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Default algorithm in Swing bad for animation
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SimpleRepaintCollector
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BooleanRepaintCollector
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CoalescingRepaintCollector
References
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Jeffrey Kesselman, Understanding the AWT
Image Types
Michael Martak, Full-Screen Exclusive Mode
API
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Sun, High Performance Graphics
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Sun, The VolatileImage API User Guide
Questions?
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Also ask via book discussion mailing list