/*
* Copyright 1990-2007 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 only, as published by the Free Software Foundation.
*
* This program 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 version 2 for more details (a copy is
* included at /legal/license.txt).
*
* You should have received a copy of the GNU General Public License
* version 2 along with this work; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
* Clara, CA 95054 or visit www.sun.com if you need additional
* information or have any questions.
*/
package com.sun.mmedia;
/**
* Decodes single images after parsing headers. Helper for GIFPlayer.
* Performs LZW decoding, palette mapping, interlacing, tranparency follow-up
*/
class GIFImageDecoder {
final static int UNDRAW_LEAVE = 1;
final static int UNDRAW_RESTORE_BACKGROUND = 2;
final static int UNDRAW_RESTORE_PREVIOUS = 3;
private int width, height, colorDepth, globalColorDepth, curColorDepth;
private byte[] globalPalette;
private byte[] curPalette;
private int[] argb;
private int[] curArgb;
private int backgroundIndex;
private int transparentColorIndex = -1;
private int undrawFlag = UNDRAW_LEAVE;
private int framePosX, framePosY, frameWidth, frameHeight;
private boolean interlace;
/// Initialize with Global Descriptor data
GIFImageDecoder(int width, int height, int colorDepth) {
this.width = width;
this.height = height;
this.colorDepth = colorDepth;
globalColorDepth = colorDepth;
globalPalette = new byte [3 * (1 << globalColorDepth)];
// default global color map - increasing grays
globalPalette[0] = 0;
globalPalette[1] = 0;
globalPalette[2] = 0;
int shift = 8 - globalColorDepth;
int add = (1 << shift) - 1;
for (int i = 1; i < (1 << globalColorDepth); ++i) {
byte gray = (byte)((i << shift) | add);
globalPalette[3 * i + 0] = gray;
globalPalette[3 * i + 1] = gray;
globalPalette[3 * i + 2] = gray;
}
backgroundIndex = -1;
curColorDepth = globalColorDepth;
curPalette = globalPalette;
argb = new int [width * height];
for (int i = 0; i < width * height; ++i)
argb[i] = 0x00badbad; // transparent
}
/// Set Global Descriptor's palette data (optional)
void setGlobalPalette(int colorDepth, byte[] palette, int backgroundIndex) {
if (curPalette == globalPalette) {
curPalette = palette;
curColorDepth = colorDepth;
}
globalPalette = palette;
globalColorDepth = colorDepth;
this.backgroundIndex = backgroundIndex;
}
/// Clear current image to background color
void clearImage() {
if (globalPalette != null && backgroundIndex >= 0) {
int bkg = getColor(backgroundIndex, globalPalette);
for (int i = 0; i < width * height; ++i)
argb[i] = bkg;
}
}
/// Get current image (after undraw)
//int [] getCurrentARGB() {
// return argb;
//}
/// Get color from palette
private int getColor(int index, byte[] palette) {
index *= 3;
return 0xff000000 | ((palette[index + 0] & 0xff) << 16) |
((palette[index + 1] & 0xff) << 8 ) |
(palette[index + 2] & 0xff);
}
/// Prepare for next frame decoding (set Local Descriptor data)
void newFrame(int relx, int rely, int width, int height, boolean interlaceFlag) {
if (relx + width > this.width)
framePosX = this.width - width;
else
framePosX = relx;
if (rely + height > this.height)
framePosY = this.height - height;
else
framePosY = rely;
// Relying that frameWidth < this.width && frameHeight << this.height
frameWidth = width;
frameHeight = height;
interlace = interlaceFlag;
}
/// Set Local Descriptor's palette data (optional)
void setLocalPalette(int colorDepth, byte[] palette) {
curColorDepth = colorDepth;
curPalette = palette;
}
/**
* Set Local Description Extension data (optional)
*
* udrawFlag: see UNDRAW_* constants
* tranparentColor: -1 - no transparent color, otherwise - index from color table
*/
void setGraphicsControl(int undrawFlag, int transparentColorIndex) {
this.undrawFlag = undrawFlag;
this.transparentColorIndex = transparentColorIndex;
}
/// Decode frame data from dataBlocks to out
boolean decodeImage(int lzwCodeSize, int dataSize, byte data[], int out[]) {
curArgb = out;
// Get saved image
System.arraycopy(argb, 0, curArgb, 0, width * height);
// LZW decode
boolean result = lzwImage(lzwCodeSize, dataSize, data);
// Undraw
switch (undrawFlag) {
case UNDRAW_LEAVE:
{
int pixel = framePosX + framePosY * width;
for (int i = 0; i < frameHeight; ++i, pixel += width)
System.arraycopy(curArgb, pixel, argb, pixel, frameWidth);
break;
}
case UNDRAW_RESTORE_BACKGROUND:
if (globalPalette != null && backgroundIndex >= 0) {
int pixel = framePosX + framePosY * width;
int wdif = width - frameWidth;
int bkg = getColor(backgroundIndex, globalPalette);
for (int i = 0; i < frameHeight; ++i, pixel += wdif)
for (int j = 0; j < frameWidth; ++j, ++pixel)
argb[pixel] = bkg;
break;
}
case UNDRAW_RESTORE_PREVIOUS:
// Do nothing
break;
}
resetLocalData();
return result;
}
// Should be called at the end of the image parsing
private void resetLocalData() {
undrawFlag = UNDRAW_LEAVE;
transparentColorIndex = -1;
curColorDepth = globalColorDepth;
curPalette = globalPalette;
}
private void drawLine(byte[] line, int y/*, int multiply*/) {
if (y > frameHeight)
return;
int pixel = (framePosY + y) * width + framePosX;
for (int i = 0; i < frameWidth; ++i, ++pixel) {
int idx = line[i] & 0xff;
if (idx != transparentColorIndex)
curArgb[pixel] = getColor(idx, curPalette);
}
}
// ------------------------- LZW decoder ------------------------
// This is converted from the native version. The java version is
// much faster when we have JIT.
private short prefix[] = new short[4096];
private byte suffix[] = new byte[4096];
private byte outCode[] = new byte[4097];
/**
* Parses image, using current palette and graphics control.
* Returns true if the image has been wholly parsed,
* false if it was truncated.
*/
private boolean lzwImage(int initCodeSize, int dataSize, byte block[]) {
byte [] rasline = new byte[frameWidth];
int OUTCODELENGTH = 4097;
int clearCode = (1 << initCodeSize);
int eofCode = clearCode + 1;
int bitMask;
int curCode;
int outCount = OUTCODELENGTH;
/* Variables used to walk read data */
int remain = dataSize;
int byteoff = 0;
int accumbits = 0;
int accumdata = 0;
/* Variables used to decompress the data */
int codeSize = initCodeSize + 1;
int maxCode = 1 << codeSize;
int codeMask = maxCode - 1;
int freeCode = clearCode + 2;
int code = 0;
int oldCode = 0;
char prevChar = 0;
/* Variables used for writing pixels */
int x = frameWidth;
int y = 0;
int off = 0;
int passinc = interlace ? 8 : 1;
int passht = passinc;
bitMask = (1 << curColorDepth) - 1;
/* Read codes until the eofCode is encountered */
for (;;) {
if (accumbits < codeSize) {
while (remain < 2) {
/* Sometimes we have one last byte to process... */
if (remain == 1 && accumbits + 8 >= codeSize)
break;
if (off > 0)
drawLine(rasline, y/*, passht*/);
/* quietly accept truncated GIF images */
return false;
}
/* 2 bytes at a time saves checking for accumbits < codeSize.
* We know we'll get enough and also that we can't overflow
* since codeSize <= 12.
*/
if (remain >= 2) {
remain -= 2;
accumdata += (block[byteoff++] & 0xff) << accumbits;
accumbits += 8;
accumdata += (block[byteoff++] & 0xff) << accumbits;
accumbits += 8;
} else {
remain--;
accumdata += (block[byteoff++] & 0xff) << accumbits;
accumbits += 8;
}
}
/* Compute the code */
code = accumdata & codeMask;
accumdata >>= codeSize;
accumbits -= codeSize;
/*
* Interpret the code
*/
if (code == clearCode) {
/* Clear code sets everything back to its initial value, then
* reads the immediately subsequent code as uncompressed data.
*/
/* Note that freeCode is one less than it is supposed to be,
* this is because it will be incremented next time round the
* loop
*/
freeCode = clearCode + 1;
codeSize = initCodeSize + 1;
maxCode = 1 << codeSize;
codeMask = maxCode - 1;
/* Continue if we've NOT reached the end, some Gif images
* contain bogus codes after the last clear code.
*/
if (y < height)
continue;
return true;
}
if (code == eofCode)
return true;
/* It must be data: save code in CurCode */
curCode = code;
/* Whenever it gets here outCount is always equal to
OUTCODELENGTH, so no need to reset outCount. */
//outCount = OUTCODELENGTH;
/* If greater or equal to freeCode, not in the hash table
* yet; repeat the last character decoded
*/
if (curCode >= freeCode) {
if (curCode > freeCode)
/*
* if we get a code too far outside our range, it
* could case the parser to start traversing parts
* of our data structure that are out of range...
*/
return true;
curCode = oldCode;
outCode[--outCount] = (byte)prevChar;
}
/* Unless this code is raw data, pursue the chain pointed
* to by curCode through the hash table to its end; each
* code in the chain puts its associated output code on
* the output queue.
*/
while (curCode > bitMask) {
outCode[--outCount] = suffix[curCode];
if (outCount == 0)
/*
* In theory this should never happen since our
* prefix and suffix arrays are monotonically
* decreasing and so outCode will only be filled
* as much as those arrays, but I don't want to
* take that chance and the test is probably
* cheap compared to the read and write operations.
* If we ever do overflow the array, we will just
* flush the rest of the data and quietly accept
* the GIF as truncated here.
*/
return true;
curCode = prefix[curCode];
}
/* The last code in the chain is treated as raw data. */
prevChar = (char)curCode;
outCode[--outCount] = (byte)prevChar;
/* Now we put the data out to the Output routine. It's
* been stacked LIFO, so deal with it that way...
*/
int len = OUTCODELENGTH - outCount; /* This is why I commented out
the code that resets outCount. */
while (--len >= 0) {
rasline[off++] = outCode[outCount++];
/* Update the X-coordinate, and if it overflows, update the
* Y-coordinate
*/
if (--x == 0) {
/* If a non-interlaced picture, just increment y to the next
* scan line. If it's interlaced, deal with the interlace as
* described in the GIF spec. Put the decoded scan line out
* to the screen if we haven't gone past the bottom of it
*/
drawLine(rasline, y/*, passht*/);
x = frameWidth;
off = 0;
/* pass inc ht ystart */
/* 0 8 8 0 */
/* 1 8 4 4 */
/* 2 4 2 2 */
/* 3 2 1 1 */
y += passinc;
while (y >= height) {
passinc = passht;
passht >>= 1;
y = passht;
if (passht == 0)
return true;
}
}
}
/* Build the hash table on-the-fly. No table is stored in the file. */
prefix[freeCode] = (short)oldCode;
suffix[freeCode] = (byte)prevChar;
oldCode = code;
/* Point to the next slot in the table. If we exceed the
* maxCode, increment the code size unless
* it's already 12. If it is, do nothing: the next code
* decompressed better be CLEAR
*/
if (++freeCode >= maxCode) {
if (codeSize < 12) {
codeSize++;
maxCode <<= 1;
codeMask = maxCode - 1;
} else
/* Just in case */
freeCode = maxCode - 1;
}
}
}
}
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