package com.terry;
import java.net.*;
import java.io.*;
import java.util.*;
import java.awt.*;
import java.awt.image.*;
public class GifDecoder {
/**
* File read status: No errors.
*/
public static final int STATUS_OK = 0;
/**
* File read status: Error decoding file (may be partially decoded)
*/
public static final int STATUS_FORMAT_ERROR = 1;
/**
* File read status: Unable to open source.
*/
public static final int STATUS_OPEN_ERROR = 2;
protected BufferedInputStream in;
protected int status;
protected int width; // full image width
protected int height; // full image height
protected boolean gctFlag; // global color table used
protected int gctSize; // size of global color table
protected int loopCount = 1; // iterations; 0 = repeat forever
protected int[] gct; // global color table
protected int[] lct; // local color table
protected int[] act; // active color table
protected int bgIndex; // background color index
protected int bgColor; // background color
protected int lastBgColor; // previous bg color
protected int pixelAspect; // pixel aspect ratio
protected boolean lctFlag; // local color table flag
protected boolean interlace; // interlace flag
protected int lctSize; // local color table size
protected int ix, iy, iw, ih; // current image rectangle
protected Rectangle lastRect; // last image rect
protected BufferedImage image; // current frame
protected BufferedImage lastImage; // previous frame
protected byte[] block = new byte[256]; // current data block
protected int blockSize = 0; // block size
// last graphic control extension info
protected int dispose = 0;
// 0=no action; 1=leave in place; 2=restore to bg; 3=restore to prev
protected int lastDispose = 0;
protected boolean transparency = false; // use transparent color
protected int delay = 0; // delay in milliseconds
protected int transIndex; // transparent color index
protected static final int MaxStackSize = 4096;
// max decoder pixel stack size
// LZW decoder working arrays
protected short[] prefix;
protected byte[] suffix;
protected byte[] pixelStack;
protected byte[] pixels;
protected ArrayList frames; // frames read from current file
protected int frameCount;
static class GifFrame {
public GifFrame(BufferedImage im, int del) {
image = im;
delay = del;
}
public BufferedImage image;
public int delay;
}
/**
* Gets display duration for specified frame.
*
* @param n int index of frame
* @return delay in milliseconds
*/
public int getDelay(int n) {
//
delay = -1;
if ((n >= 0) && (n < frameCount)) {
delay = ((GifFrame) frames.get(n)).delay;
}
return delay;
}
/**
* Gets the number of frames read from file.
* @return frame count
*/
public int getFrameCount() {
return frameCount;
}
/**
* Gets the first (or only) image read.
*
* @return BufferedImage containing first frame, or null if none.
*/
public BufferedImage getImage() {
return getFrame(0);
}
/**
* Gets the "Netscape" iteration count, if any.
* A count of 0 means repeat indefinitiely.
*
* @return iteration count if one was specified, else 1.
*/
public int getLoopCount() {
return loopCount;
}
/**
* Creates new frame image from current data (and previous
* frames as specified by their disposition codes).
*/
protected void setPixels() {
// expose destination image's pixels as int array
int[] dest =
((DataBufferInt) image.getRaster().getDataBuffer()).getData();
// fill in starting image contents based on last image's dispose code
if (lastDispose > 0) {
if (lastDispose == 3) {
// use image before last
int n = frameCount - 2;
if (n > 0) {
lastImage = getFrame(n - 1);
} else {
lastImage = null;
}
}
if (lastImage != null) {
int[] prev =
((DataBufferInt) lastImage.getRaster().getDataBuffer()).getData();
System.arraycopy(prev, 0, dest, 0, width * height);
// copy pixels
if (lastDispose == 2) {
// fill last image rect area with background color
Graphics2D g = image.createGraphics();
Color c = null;
if (transparency) {
c = new Color(0, 0, 0, 0); // assume background is transparent
} else {
c = new Color(lastBgColor); // use given background color
}
g.setColor(c);
g.setComposite(AlphaComposite.Src); // replace area
g.fill(lastRect);
g.dispose();
}
}
}
// copy each source line to the appropriate place in the destination
int pass = 1;
int inc = 8;
int iline = 0;
for (int i = 0; i < ih; i++) {
int line = i;
if (interlace) {
if (iline >= ih) {
pass++;
switch (pass) {
case 2 :
iline = 4;
break;
case 3 :
iline = 2;
inc = 4;
break;
case 4 :
iline = 1;
inc = 2;
}
}
line = iline;
iline += inc;
}
line += iy;
if (line < height) {
int k = line * width;
int dx = k + ix; // start of line in dest
int dlim = dx + iw; // end of dest line
if ((k + width) < dlim) {
dlim = k + width; // past dest edge
}
int sx = i * iw; // start of line in source
while (dx < dlim) {
// map color and insert in destination
int index = ((int) pixels[sx++]) & 0xff;
int c = act[index];
if (c != 0) {
dest[dx] = c;
}
dx++;
}
}
}
}
/**
* Gets the image contents of frame n.
*
* @return BufferedImage representation of frame, or null if n is invalid.
*/
public BufferedImage getFrame(int n) {
BufferedImage im = null;
if ((n >= 0) && (n < frameCount)) {
im = ((GifFrame) frames.get(n)).image;
}
return im;
}
/**
* Gets image size.
*
* @return GIF image dimensions
*/
public Dimension getFrameSize() {
return new Dimension(width, height);
}
/**
* Reads GIF image from stream
*
* @param BufferedInputStream containing GIF file.
* @return read status code (0 = no errors)
*/
public int read(BufferedInputStream is) {
init();
if (is != null) {
in = is;
readHeader();
if (!err()) {
readContents();
if (frameCount < 0) {
status = STATUS_FORMAT_ERROR;
}
}
} else {
status = STATUS_OPEN_ERROR;
}
try {
is.close();
} catch (IOException e) {
}
return status;
}
/**
* Reads GIF image from stream
*
* @param InputStream containing GIF file.
* @return read status code (0 = no errors)
*/
public int read(InputStream is) {
init();
if (is != null) {
if (!(is instanceof BufferedInputStream))
is = new BufferedInputStream(is);
in = (BufferedInputStream) is;
readHeader();
if (!err()) {
readContents();
if (frameCount < 0) {
status = STATUS_FORMAT_ERROR;
}
}
} else {
status = STATUS_OPEN_ERROR;
}
try {
is.close();
} catch (IOException e) {
}
return status;
}
/**
* Reads GIF file from specified file/URL source
* (URL assumed if name contains ":/" or "file:")
*
* @param name String containing source
* @return read status code (0 = no errors)
*/
public int read(String name) {
status = STATUS_OK;
try {
name = name.trim().toLowerCase();
if ((name.indexOf("file:") >= 0) ||
(name.indexOf(":/") > 0)) {
URL url = new URL(name);
in = new BufferedInputStream(url.openStream());
} else {
in = new BufferedInputStream(new FileInputStream(name));
}
status = read(in);
} catch (IOException e) {
status = STATUS_OPEN_ERROR;
}
return status;
}
/**
* Decodes LZW image data into pixel array.
* Adapted from John Cristy's ImageMagick.
*/
protected void decodeImageData() {
int NullCode =
