/*
* Open Source Physics software is free software as described near the bottom of this code file.
*
* For additional information and documentation on Open Source Physics please see:
* <http://www.opensourcephysics.org/>
*/
/*
* The org.opensourcephysics.media.gif package provides animated gif
* implementations of the Video and VideoRecorder interfaces.
*
* Copyright (c) 2014 Douglas Brown and Wolfgang Christian.
*
* This is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston MA 02111-1307 USA
* or view the license online at http://www.gnu.org/copyleft/gpl.html
*
* For additional information and documentation on Open Source Physics,
* please see <http://www.opensourcephysics.org/>.
*/
package org.opensourcephysics.media.gif;
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import java.awt.image.DataBufferInt;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.util.ArrayList;
import org.opensourcephysics.tools.ResourceLoader;
/**
* Class GifDecoder - Decodes a GIF file into one or more frames.
* <br><pre>
* Example:
* GifDecoder d = new GifDecoder();
* d.read("sample.gif");
* int n = d.getFrameCount();
* for (int i = 0; i < n; i++) {
* BufferedImage frame = d.getFrame(i); // frame i
* int t = d.getDelay(i); // display duration of frame in milliseconds
* // do something with frame
* }
* </pre>
* No copyright asserted on the source code of this class. May be used for
* any purpose, however, refer to the Unisys LZW patent for any additional
* restrictions. Please forward any corrections to kweiner@fmsware.com.
*
* @author Kevin Weiner, FM Software; LZW decoder adapted from John Cristy's ImageMagick.
* @version 1.03 November 2003
*/
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<GifFrame> frames; // frames read from current file
protected int frameCount;
static class GifFrame {
BufferedImage image;
int delay;
GifFrame(BufferedImage im, int del) {
image = im;
delay = del;
}
}
/**
* 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 = 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 = pixels[sx++]&0xff;
int c = act[index];
if(c!=0) {
dest[dx] = c;
}
dx++;
}
}
}
}
/**
* Gets the image contents of frame n.
*
* @param n the frame number
* @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 = 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 input the BufferedInputStream containing GIF file.
* @return read status code (0 = no errors)
*/
public int read(BufferedInputStream input) {
init();
if(input!=null) {
in = input;
readHeader();
if(!err()) {
readContents();
if(frameCount<0) {
status = STATUS_FORMAT_ERROR;
}
}
} else {
status = STATUS_OPEN_ERROR;
}
try {
input.close();
} catch(IOException ex) {
/** empty block */
}
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;
// modified by Doug Brown 2007-10-17
try {
in = new BufferedInputStream(ResourceLoader.openInputStream(name));
status = read(in);
} catch(Exception 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 = -1;
int npix = iw*ih;
int available, clear, code_mask, code_size, end_of_information, in_code, old_code, bits, code, count, i, datum, data_size, first, top, bi, pi;
if((pixels==null)||(pixels.length<npix)) {
pixels = new byte[npix]; // allocate new pixel array
}
if(prefix==null) {
prefix = new short[MaxStackSize];
}
if(suffix==null) {
suffix = new byte[MaxStackSize];
}
if(pixelStack==null) {
pixelStack = new byte[MaxStackSize+1];
}
// Initialize GIF data stream decoder.
data_size = read();
clear = 1<<data_size;
end_of_information = clear+1;
available = clear+2;
old_code = NullCode;
code_size = data_size+1;
code_mask = (1<<code_size)-1;
for(code = 0; code<clear; code++) {
prefix[code] = 0;
suffix[code] = (byte) code;
}
// Decode GIF pixel stream.
datum = bits = count = first = top = pi = bi = 0;
for(i = 0; i<npix; ) {
if(top==0) {
if(bits<code_size) {
// Load bytes until there are enough bits for a code.
if(count==0) {
// Read a new data block.
count = readBlock();
if(count<=0) {
break;
}
bi = 0;
}
datum += (block[bi]&0xff)<<bits;
bits += 8;
bi++;
count--;
continue;
}
// Get the next code.
code = datum&code_mask;
datum >>= code_size;
bits -= code_size;
// Interpret the code
if((code>available)||(code==end_of_information)) {
break;
}
if(code==clear) {
// Reset decoder.
code_size = data_size+1;
code_mask = (1<<code_size)-1;
available = clear+2;
old_code = NullCode;
continue;
}
if(old_code==NullCode) {
pixelStack[top++] = suffix[code];
old_code = code;
first = code;
continue;
}
in_code = code;
if(code==available) {
pixelStack[top++] = (byte) first;
code = old_code;
}
while(code>clear) {
pixelStack[top++] = suffix[code];
code = prefix[code];
}
first = suffix[code]&0xff;
// Add a new string to the string table,
if(available>=MaxStackSize) {
break;
}
pixelStack[top++] = (byte) first;
prefix[available] = (short) old_code;
suffix[available] = (byte) first;
available++;
if(((available&code_mask)==0)&&(available<MaxStackSize)) {
code_size++;
code_mask += available;
}
old_code = in_code;
}
// Pop a pixel off the pixel stack.
top--;
pixels[pi++] = pixelStack[top];
i++;
}
for(i = pi; i<npix; i++) {
pixels[i] = 0; // clear missing pixels
}
}
/**
* Returns true if an error was encountered during reading/decoding
* @return true if an error occurred
*/
protected boolean err() {
return status!=STATUS_OK;
}
/**
* Initializes or re-initializes reader
*/
protected void init() {
status = STATUS_OK;
frameCount = 0;
frames = new ArrayList<GifFrame>();
gct = null;
lct = null;
}
/**
* Reads a single byte from the input stream.
* @return the byte read
*/
protected int read() {
int curByte = 0;
try {
curByte = in.read();
} catch(IOException e) {
status = STATUS_FORMAT_ERROR;
}
return curByte;
}
/**
* Reads next variable length block from input.
*
* @return number of bytes stored in "buffer"
*/
protected int readBlock() {
blockSize = read();
int n = 0;
if(blockSize>0) {
try {
int count = 0;
while(n<blockSize) {
count = in.read(block, n, blockSize-n);
if(count==-1) {
break;
}
n += count;
}
} catch(IOException ex) {
/** empty block */
}
if(n<blockSize) {
status = STATUS_FORMAT_ERROR;
}
}
return n;
}
/**
* Reads color table as 256 RGB integer values
*
* @param ncolors int number of colors to read
* @return int array containing 256 colors (packed ARGB with full alpha)
*/
protected int[] readColorTable(int ncolors) {
int nbytes = 3*ncolors;
int[] tab = null;
byte[] c = new byte[nbytes];
int n = 0;
try {
n = in.read(c);
} catch(IOException ex) {
/** empty block */
}
if(n<nbytes) {
status = STATUS_FORMAT_ERROR;
} else {
tab = new int[256]; // max size to avoid bounds checks
int i = 0;
int j = 0;
while(i<ncolors) {
int r = c[j++]&0xff;
int g = c[j++]&0xff;
int b = c[j++]&0xff;
tab[i++] = 0xff000000|(r<<16)|(g<<8)|b;
}
}
return tab;
}
/**
* Main file parser. Reads GIF content blocks.
*/
protected void readContents() {
// read GIF file content blocks
boolean done = false;
while(!(done||err())) {
int code = read();
switch(code) {
case 0x2C : // image separator
readImage();
break;
case 0x21 : // extension
code = read();
switch(code) {
case 0xf9 : // graphics control extension
readGraphicControlExt();
break;
case 0xff : // application extension
readBlock();
String app = ""; //$NON-NLS-1$
for(int i = 0; i<11; i++) {
app += (char) block[i];
}
if(app.equals("NETSCAPE2.0")) { //$NON-NLS-1$
readNetscapeExt();
} else {
skip(); // don't care
}
break;
default : // uninteresting extension
skip();
}
break;
case 0x3b : // terminator
done = true;
break;
case 0x00 : // bad byte, but keep going and see what happens
break;
default :
status = STATUS_FORMAT_ERROR;
}
}
}
/**
* Reads Graphics Control Extension values
*/
protected void readGraphicControlExt() {
read(); // block size
int packed = read(); // packed fields
dispose = (packed&0x1c)>>2; // disposal method
if(dispose==0) {
dispose = 1; // elect to keep old image if discretionary
}
transparency = (packed&1)!=0;
delay = readShort()*10; // delay in milliseconds
transIndex = read(); // transparent color index
read(); // block terminator
}
/**
* Reads GIF file header information.
*/
protected void readHeader() {
String id = ""; //$NON-NLS-1$
for(int i = 0; i<6; i++) {
id += (char) read();
}
if(!id.startsWith("GIF")) { //$NON-NLS-1$
status = STATUS_FORMAT_ERROR;
return;
}
readLSD();
if(gctFlag&&!err()) {
gct = readColorTable(gctSize);
bgColor = gct[bgIndex];
}
}
/**
* Reads next frame image
*/
protected void readImage() {
ix = readShort(); // (sub)image position & size
iy = readShort();
iw = readShort();
ih = readShort();
int packed = read();
lctFlag = (packed&0x80)!=0; // 1 - local color table flag
interlace = (packed&0x40)!=0; // 2 - interlace flag
// 3 - sort flag
// 4-5 - reserved
lctSize = 2<<(packed&7); // 6-8 - local color table size
if(lctFlag) {
lct = readColorTable(lctSize); // read table
act = lct; // make local table active
} else {
act = gct; // make global table active
if(bgIndex==transIndex) {
bgColor = 0;
}
}
int save = 0;
if(transparency) {
save = act[transIndex];
act[transIndex] = 0; // set transparent color if specified
}
if(act==null) {
status = STATUS_FORMAT_ERROR; // no color table defined
}
if(err()) {
return;
}
decodeImageData(); // decode pixel data
skip();
if(err()) {
return;
}
frameCount++;
// create new image to receive frame data
image = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB_PRE);
setPixels(); // transfer pixel data to image
frames.add(new GifFrame(image, delay)); // add image to frame list
if(transparency) {
act[transIndex] = save;
}
resetFrame();
}
/**
* Reads Logical Screen Descriptor
*/
protected void readLSD() {
// logical screen size
width = readShort();
height = readShort();
// packed fields
int packed = read();
gctFlag = (packed&0x80)!=0; // 1 : global color table flag
// 2-4 : color resolution
// 5 : gct sort flag
gctSize = 2<<(packed&7); // 6-8 : gct size
bgIndex = read(); // background color index
pixelAspect = read(); // pixel aspect ratio
}
/**
* Reads Netscape extenstion to obtain iteration count
*/
protected void readNetscapeExt() {
do {
readBlock();
if(block[0]==1) {
// loop count sub-block
int b1 = block[1]&0xff;
int b2 = block[2]&0xff;
loopCount = (b2<<8)|b1;
}
} while((blockSize>0)&&!err());
}
/**
* Reads next 16-bit value, LSB first
* @return the value read
*/
protected int readShort() {
// read 16-bit value, LSB first
return read()|(read()<<8);
}
/**
* Resets frame state for reading next image.
*/
protected void resetFrame() {
lastDispose = dispose;
lastRect = new Rectangle(ix, iy, iw, ih);
lastImage = image;
lastBgColor = bgColor;
lct = null;
}
/**
* Skips variable length blocks up to and including
* next zero length block.
*/
protected void skip() {
do {
readBlock();
} while((blockSize>0)&&!err());
}
}
/*
* Open Source Physics software is free software; you can redistribute
* it and/or modify it under the terms of the GNU General Public License (GPL) as
* published by the Free Software Foundation; either version 2 of the License,
* or(at your option) any later version.
* Code that uses any portion of the code in the org.opensourcephysics package
* or any subpackage (subdirectory) of this package must must also be be released
* under the GNU GPL license.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston MA 02111-1307 USA
* or view the license online at http://www.gnu.org/copyleft/gpl.html
*
* Copyright (c) 2007 The Open Source Physics project
* http://www.opensourcephysics.org
*/