org.opensourcephysics.media.gif
Class AnimatedGifEncoder

java.lang.Object
  org.opensourcephysics.media.gif.AnimatedGifEncoder

public class AnimatedGifEncoder
extends java.lang.Object

Class AnimatedGifEncoder - Encodes a GIF file consisting of one or more frames.

 Example:
    AnimatedGifEncoder e = new AnimatedGifEncoder();
    e.start(outputFileName);
    e.setDelay(1000);   // 1 frame per sec
    e.addFrame(image1);
    e.addFrame(image2);
    e.finish();
 

No copyright asserted on the source code of this class. May be used for any purpose, however, refer to the Unisys LZW patent for restrictions on use of the associated LZWEncoder class. Please forward any corrections to kweiner@fmsware.com.

Version:

1.03 November 2003

Author:

Kevin Weiner, FM Software

Field Summary

protected boolean	closeStream
protected int	colorDepth
protected byte[]	colorTab
protected int	delay
protected int	dispose
protected boolean	firstFrame
protected int	height
protected java.awt.image.BufferedImage	image
protected byte[]	indexedPixels
protected java.io.OutputStream	out
protected int	palSize
protected byte[]	pixels
protected int	repeat
protected int	sample
protected boolean	sizeSet
protected boolean	started
protected int	transIndex
protected java.awt.Color	transparent
protected boolean[]	usedEntry
protected int	width

Constructor Summary

AnimatedGifEncoder()

Method Summary

boolean	addFrame(java.awt.image.BufferedImage im) Adds next GIF frame.
protected void	analyzePixels() Analyzes image colors and creates color map.
protected int	findClosest(java.awt.Color c) Returns index of palette color closest to c
boolean	finish() Flushes any pending data and closes output file.
protected void	getImagePixels() Extracts image pixels into byte array "pixels"
void	setDelay(int ms) Sets the delay time between each frame, or changes it for subsequent frames (applies to last frame added).
void	setDispose(int code) Sets the GIF frame disposal code for the last added frame and any subsequent frames.
void	setFrameRate(float fps) Sets frame rate in frames per second.
void	setQuality(int quality) Sets quality of color quantization (conversion of images to the maximum 256 colors allowed by the GIF specification).
void	setRepeat(int iter) Sets the number of times the set of GIF frames should be played.
void	setSize(int w, int h) Sets the GIF frame size.
void	setTransparent(java.awt.Color c) Sets the transparent color for the last added frame and any subsequent frames.
boolean	start(java.io.OutputStream os) Initiates GIF file creation on the given stream.
boolean	start(java.lang.String file) Initiates writing of a GIF file with the specified name.
protected void	writeGraphicCtrlExt() Writes Graphic Control Extension
protected void	writeImageDesc() Writes Image Descriptor
protected void	writeLSD() Writes Logical Screen Descriptor
protected void	writeNetscapeExt() Writes Netscape application extension to define repeat count.
protected void	writePalette() Writes color table
protected void	writePixels() Encodes and writes pixel data
protected void	writeShort(int value) Write 16-bit value to output stream, LSB first
protected void	writeString(java.lang.String s) Writes string to output stream

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

width

protected int width

height

protected int height

transparent

protected java.awt.Color transparent

transIndex

protected int transIndex

repeat

protected int repeat

delay

protected int delay

started

protected boolean started

out

protected java.io.OutputStream out

image

protected java.awt.image.BufferedImage image

pixels

protected byte[] pixels

indexedPixels

protected byte[] indexedPixels

colorDepth

protected int colorDepth

colorTab

protected byte[] colorTab

usedEntry

protected boolean[] usedEntry

palSize

protected int palSize

dispose

protected int dispose

closeStream

protected boolean closeStream

firstFrame

protected boolean firstFrame

sizeSet

protected boolean sizeSet

sample

protected int sample

Constructor Detail

AnimatedGifEncoder

public AnimatedGifEncoder()

Method Detail

setDelay

public void setDelay(int ms)

Sets the delay time between each frame, or changes it for subsequent frames (applies to last frame added).

Parameters:

ms - int delay time in milliseconds

setDispose

public void setDispose(int code)

Sets the GIF frame disposal code for the last added frame and any subsequent frames. Default is 0 if no transparent color has been set, otherwise 2.

Parameters:

code - int disposal code.

setRepeat

public void setRepeat(int iter)

Sets the number of times the set of GIF frames should be played. Default is 1; 0 means play indefinitely. Must be invoked before the first image is added.

Parameters:

iter - int number of iterations.

setTransparent

public void setTransparent(java.awt.Color c)

Sets the transparent color for the last added frame and any subsequent frames. Since all colors are subject to modification in the quantization process, the color in the final palette for each frame closest to the given color becomes the transparent color for that frame. May be set to null to indicate no transparent color.

Parameters:

c - Color to be treated as transparent on display.

addFrame

public boolean addFrame(java.awt.image.BufferedImage im)

Adds next GIF frame. The frame is not written immediately, but is actually deferred until the next frame is received so that timing data can be inserted. Invoking finish() flushes all frames. If setSize was not invoked, the size of the first image is used for all subsequent frames.

Parameters:

im - BufferedImage containing frame to write.

Returns:

true if successful.

finish

public boolean finish()

Flushes any pending data and closes output file. If writing to an OutputStream, the stream is not closed.

Returns:

true if successfully flushed and reset

setFrameRate

public void setFrameRate(float fps)

Sets frame rate in frames per second. Equivalent to setDelay(1000/fps).

Parameters:

fps - float frame rate (frames per second)

setQuality

public void setQuality(int quality)

Sets quality of color quantization (conversion of images to the maximum 256 colors allowed by the GIF specification). Lower values (minimum = 1) produce better colors, but slow processing significantly. 10 is the default, and produces good color mapping at reasonable speeds. Values greater than 20 do not yield significant improvements in speed.

Parameters:

quality - int greater than 0.

setSize

public void setSize(int w,
                    int h)

Sets the GIF frame size. The default size is the size of the first frame added if this method is not invoked.

Parameters:

w - int frame width.

h - int frame width.

start

public boolean start(java.io.OutputStream os)

Initiates GIF file creation on the given stream. The stream is not closed automatically.

Parameters:

os - OutputStream on which GIF images are written.

Returns:

false if initial write failed.

start

public boolean start(java.lang.String file)

Initiates writing of a GIF file with the specified name.

Parameters:

file - String containing output file name.

Returns:

false if open or initial write failed.

analyzePixels

protected void analyzePixels()

Analyzes image colors and creates color map.

findClosest

protected int findClosest(java.awt.Color c)

Returns index of palette color closest to c

getImagePixels

protected void getImagePixels()

Extracts image pixels into byte array "pixels"

writeGraphicCtrlExt

protected void writeGraphicCtrlExt()
                            throws java.io.IOException

Writes Graphic Control Extension

Throws:

java.io.IOException

writeImageDesc

protected void writeImageDesc()
                       throws java.io.IOException

Writes Image Descriptor

Throws:

java.io.IOException

writeLSD

protected void writeLSD()
                 throws java.io.IOException

Writes Logical Screen Descriptor

Throws:

java.io.IOException

writeNetscapeExt

protected void writeNetscapeExt()
                         throws java.io.IOException

Writes Netscape application extension to define repeat count.

Throws:

java.io.IOException

writePalette

protected void writePalette()
                     throws java.io.IOException

Writes color table

Throws:

java.io.IOException

writePixels

protected void writePixels()
                    throws java.io.IOException

Encodes and writes pixel data

Throws:

java.io.IOException

writeShort

protected void writeShort(int value)
                   throws java.io.IOException

Write 16-bit value to output stream, LSB first

Throws:

java.io.IOException

writeString

protected void writeString(java.lang.String s)
                    throws java.io.IOException

Writes string to output stream

Throws:

java.io.IOException