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/*
This file is part of the iText (R) project.
Copyright (c) 1998-2022 iText Group NV
Authors: Bruno Lowagie, Paulo Soares, et al.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License version 3
as published by the Free Software Foundation with the addition of the
following permission added to Section 15 as permitted in Section 7(a):
FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
ITEXT GROUP. ITEXT GROUP DISCLAIMS THE WARRANTY OF NON INFRINGEMENT
OF THIRD PARTY RIGHTS
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 Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program; if not, see http://www.gnu.org/licenses or write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA, 02110-1301 USA, or download the license from the following URL:
http://itextpdf.com/terms-of-use/
The interactive user interfaces in modified source and object code versions
of this program must display Appropriate Legal Notices, as required under
Section 5 of the GNU Affero General Public License.
In accordance with Section 7(b) of the GNU Affero General Public License,
a covered work must retain the producer line in every PDF that is created
or manipulated using iText.
You can be released from the requirements of the license by purchasing
a commercial license. Buying such a license is mandatory as soon as you
develop commercial activities involving the iText software without
disclosing the source code of your own applications.
These activities include: offering paid services to customers as an ASP,
serving PDFs on the fly in a web application, shipping iText with a closed
source product.
For more information, please contact iText Software Corp. at this
address: [email protected]
*/
package com.itextpdf.io.image;
import com.itextpdf.io.exceptions.IOException;
import com.itextpdf.io.font.PdfEncodings;
import com.itextpdf.io.util.StreamUtil;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
public final class GifImageHelper {
// max decoder pixel stack size
static final int MAX_STACK_SIZE = 4096;
private static class GifParameters {
public GifParameters(GifImageData image) {
this.image = image;
}
InputStream input;
// global color table used
boolean gctFlag;
// background color index
int bgIndex;
// background color
int bgColor;
// pixel aspect ratio
int pixelAspect;
// local color table flag
boolean lctFlag;
// interlace flag
boolean interlace;
// local color table size
int lctSize;
// current image rectangle
int ix, iy, iw, ih;
// current data block
byte[] block = new byte[256];
// block size
int blockSize = 0;
// last graphic control extension info
// 0=no action; 1=leave in place; 2=restore to bg; 3=restore to prev
int dispose = 0;
// use transparent color
boolean transparency = false;
// delay in milliseconds
int delay = 0;
// transparent color index
int transIndex;
// LZW decoder working arrays
short[] prefix;
byte[] suffix;
byte[] pixelStack;
byte[] pixels;
byte[] m_out;
int m_bpc;
int m_gbpc;
byte[] m_global_table;
byte[] m_local_table;
byte[] m_curr_table;
int m_line_stride;
byte[] fromData;
URL fromUrl;
int currentFrame;
GifImageData image;
}
/**
* Reads image source and fills GifImage object with parameters (frames, width, height)
* @param image GifImage
*/
public static void processImage(GifImageData image) {
processImage(image, -1);
}
/**
* Reads image source and fills GifImage object with parameters (frames, width, height)
* @param image GifImage
* @param lastFrameNumber the last frame of the gif image should be read
*/
public static void processImage(GifImageData image, int lastFrameNumber) {
GifParameters gif = new GifParameters(image);
InputStream gifStream;
try {
if (image.getData() == null) {
image.loadData();
}
gifStream = new ByteArrayInputStream(image.getData());
process(gifStream, gif, lastFrameNumber);
} catch (java.io.IOException e) {
throw new IOException(IOException.GifImageException, e);
}
}
private static void process(InputStream stream, GifParameters gif, int lastFrameNumber) throws java.io.IOException {
gif.input = stream;
readHeader(gif);
readContents(gif, lastFrameNumber);
if (gif.currentFrame <= lastFrameNumber) {
throw new IOException(IOException.CannotFind1Frame).setMessageParams(lastFrameNumber);
}
}
/**
* Reads GIF file header information.
*/
private static void readHeader(GifParameters gif) throws java.io.IOException {
StringBuilder id = new StringBuilder("");
for (int i = 0; i < 6; i++)
id.append((char)gif.input.read());
if (!id.toString().startsWith("GIF8")) {
throw new IOException(IOException.GifSignatureNotFound);
}
readLSD(gif);
if (gif.gctFlag) {
gif.m_global_table = readColorTable(gif.m_gbpc, gif);
}
}
/**
* Reads Logical Screen Descriptor
*/
private static void readLSD(GifParameters gif) throws java.io.IOException {
// logical screen size
gif.image.setLogicalWidth(readShort(gif));
gif.image.setLogicalHeight(readShort(gif));
// packed fields
int packed = gif.input.read();
// 1 : global color table flag
gif.gctFlag = (packed & 0x80) != 0;
gif.m_gbpc = (packed & 7) + 1;
// background color index
gif.bgIndex = gif.input.read();
// pixel aspect ratio
gif.pixelAspect = gif.input.read();
}
/**
* Reads next 16-bit value, LSB first
*/
private static int readShort(GifParameters gif) throws java.io.IOException {
// read 16-bit value, LSB first
return gif.input.read() | gif.input.read() << 8;
}
/**
* Reads next variable length block from input.
*
* @return number of bytes stored in "buffer"
*/
private static int readBlock(GifParameters gif) throws java.io.IOException {
gif.blockSize = gif.input.read();
if (gif.blockSize <= 0)
return gif.blockSize = 0;
gif.blockSize = gif.input.read(gif.block, 0, gif.blockSize);
return gif.blockSize;
}
private static byte[] readColorTable(int bpc, GifParameters gif) throws java.io.IOException {
int ncolors = 1 << bpc;
int nbytes = 3*ncolors;
bpc = newBpc(bpc);
byte[] table = new byte[(1 << bpc) * 3];
StreamUtil.readFully(gif.input, table, 0, nbytes);
return table;
}
private static int newBpc(int bpc) {
switch (bpc) {
case 1:
case 2:
case 4:
break;
case 3:
return 4;
default:
return 8;
}
return bpc;
}
private static void readContents(GifParameters gif, int lastFrameNumber) throws java.io.IOException {
// read GIF file content blocks
boolean done = false;
gif.currentFrame = 0;
while (!done) {
int code = gif.input.read();
switch (code) {
case 0x2C:
// image separator
readFrame(gif);
if (gif.currentFrame == lastFrameNumber) {
done = true;
}
gif.currentFrame++;
break;
case 0x21:
// extension
code = gif.input.read();
switch (code) {
case 0xf9:
// graphics control extension
readGraphicControlExt(gif);
break;
case 0xff:
// application extension
readBlock(gif);
// don't care
skip(gif);
break;
default:
// uninteresting extension
skip(gif);
}
break;
default:
done = true;
break;
}
}
}
/**
* Reads next frame image
*/
private static void readFrame(GifParameters gif) throws java.io.IOException {
// (sub)image position & size
gif.ix = readShort(gif);
gif.iy = readShort(gif);
gif.iw = readShort(gif);
gif.ih = readShort(gif);
int packed = gif.input.read();
// 1 - local color table flag
gif.lctFlag = (packed & 0x80) != 0;
// 2 - interlace flag
gif.interlace = (packed & 0x40) != 0;
// 3 - sort flag
// 4-5 - reserved
// 6-8 - local color table size
gif.lctSize = 2 << (packed & 7);
gif.m_bpc = newBpc(gif.m_gbpc);
if (gif.lctFlag) {
// read table
gif.m_curr_table = readColorTable((packed & 7) + 1, gif);
gif.m_bpc = newBpc((packed & 7) + 1);
}
else {
gif.m_curr_table = gif.m_global_table;
}
if (gif.transparency && gif.transIndex >= gif.m_curr_table.length / 3)
gif.transparency = false;
// Acrobat 5.05 doesn't like this combination
if (gif.transparency && gif.m_bpc == 1) {
byte[] tp = new byte[12];
System.arraycopy(gif.m_curr_table, 0, tp, 0, 6);
gif.m_curr_table = tp;
gif.m_bpc = 2;
}
// decode pixel data
boolean skipZero = decodeImageData(gif);
if (!skipZero)
skip(gif);
try {
Object[] colorspace = new Object[4];
colorspace[0] = "/Indexed";
colorspace[1] = "/DeviceRGB";
int len = gif.m_curr_table.length;
colorspace[2] = len / 3 - 1;
colorspace[3] = PdfEncodings.convertToString(gif.m_curr_table, null);
Map ad = new HashMap<>();
ad.put("ColorSpace", colorspace);
RawImageData img = new RawImageData(gif.m_out, ImageType.GIF);
RawImageHelper.updateRawImageParameters(img, gif.iw, gif.ih, 1, gif.m_bpc, gif.m_out);
RawImageHelper.updateImageAttributes(img, ad);
gif.image.addFrame(img);
if (gif.transparency) {
img.setTransparency(new int[]{gif.transIndex, gif.transIndex});
}
} catch (Exception e) {
throw new IOException(IOException.GifImageException, e);
}
}
private static boolean decodeImageData(GifParameters gif) throws java.io.IOException {
int NullCode = -1;
int npix = gif.iw * gif.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;
boolean skipZero = false;
if (gif.prefix == null)
gif.prefix = new short[MAX_STACK_SIZE];
if (gif.suffix == null)
gif.suffix = new byte[MAX_STACK_SIZE];
if (gif.pixelStack == null)
gif.pixelStack = new byte[MAX_STACK_SIZE +1];
gif.m_line_stride = (gif.iw * gif.m_bpc + 7) / 8;
gif.m_out = new byte[gif.m_line_stride * gif.ih];
int pass = 1;
int inc = gif.interlace ? 8 : 1;
int line = 0;
int xpos = 0;
// Initialize GIF data stream decoder.
data_size = gif.input.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++) {
gif.prefix[code] = 0;
gif.suffix[code] = (byte) code;
}
// Decode GIF pixel stream.
datum = bits = count = first = top = 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(gif);
if (count <= 0) {
skipZero = true;
break;
}
bi = 0;
}
datum += (gif.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) {
gif.pixelStack[top++] = gif.suffix[code];
old_code = code;
first = code;
continue;
}
in_code = code;
if (code == available) {
gif.pixelStack[top++] = (byte) first;
code = old_code;
}
while (code > clear) {
gif.pixelStack[top++] = gif.suffix[code];
code = gif.prefix[code];
}
first = gif.suffix[code] & 0xff;
// Add a new string to the string table,
if (available >= MAX_STACK_SIZE)
break;
gif.pixelStack[top++] = (byte) first;
gif.prefix[available] = (short) old_code;
gif.suffix[available] = (byte) first;
available++;
if ((available & code_mask) == 0 && available < MAX_STACK_SIZE) {
code_size++;
code_mask += available;
}
old_code = in_code;
}
// Pop a pixel off the pixel stack.
top--;
i++;
setPixel(xpos, line, gif.pixelStack[top], gif);
++xpos;
if (xpos >= gif.iw) {
xpos = 0;
line += inc;
if (line >= gif.ih) {
if (gif.interlace) {
do {
pass++;
switch (pass) {
case 2:
line = 4;
break;
case 3:
line = 2;
inc = 4;
break;
case 4:
line = 1;
inc = 2;
break;
default:
// this shouldn't happen
line = gif.ih - 1;
inc = 0;
}
} while (line >= gif.ih);
}
else {
// this shouldn't happen
line = gif.ih - 1;
inc = 0;
}
}
}
}
return skipZero;
}
private static void setPixel(int x, int y, int v, GifParameters gif) {
if (gif.m_bpc == 8) {
int pos = x + gif.iw * y;
gif.m_out[pos] = (byte)v;
}
else {
int pos = gif.m_line_stride * y + x / (8 / gif.m_bpc);
int vout = v << 8 - gif.m_bpc * (x % (8 / gif.m_bpc))- gif.m_bpc;
gif.m_out[pos] |= (byte) vout;
}
}
/**
* Reads Graphics Control Extension values
*/
private static void readGraphicControlExt(GifParameters gif) throws java.io.IOException {
// block size
gif.input.read();
// packed fields
int packed = gif.input.read();
// disposal method
gif.dispose = (packed & 0x1c) >> 2;
if (gif.dispose == 0){
// elect to keep old image if discretionary
gif.dispose = 1;
}
gif.transparency = (packed & 1) != 0;
// delay in milliseconds
gif.delay = readShort(gif) * 10;
// transparent color index
gif.transIndex = gif.input.read();
// block terminator
gif.input.read();
}
/**
* Skips variable length blocks up to and including
* next zero length block.
*/
private static void skip(GifParameters gif) throws java.io.IOException {
do {
readBlock(gif);
} while (gif.blockSize > 0);
}
}
