/*******************************************************************************
* Copyright (c) 2000, 2012 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.swt.internal.image;
import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import java.io.*;
public final class GIFFileFormat extends FileFormat {
String signature;
int screenWidth, screenHeight, backgroundPixel, bitsPerPixel, defaultDepth;
int disposalMethod = 0;
int delayTime = 0;
int transparentPixel = -1;
int repeatCount = 1;
static final int GIF_APPLICATION_EXTENSION_BLOCK_ID = 0xFF;
static final int GIF_GRAPHICS_CONTROL_BLOCK_ID = 0xF9;
static final int GIF_PLAIN_TEXT_BLOCK_ID = 0x01;
static final int GIF_COMMENT_BLOCK_ID = 0xFE;
static final int GIF_EXTENSION_BLOCK_ID = 0x21;
static final int GIF_IMAGE_BLOCK_ID = 0x2C;
static final int GIF_TRAILER_ID = 0x3B;
static final byte [] GIF89a = new byte[] { (byte)'G', (byte)'I', (byte)'F', (byte)'8', (byte)'9', (byte)'a' };
static final byte [] NETSCAPE2_0 = new byte[] { (byte)'N', (byte)'E', (byte)'T', (byte)'S', (byte)'C', (byte)'A', (byte)'P', (byte)'E', (byte)'2', (byte)'.', (byte)'0' };
/**
* Answer a palette containing numGrays
* shades of gray, ranging from black to white.
*/
static PaletteData grayRamp(int numGrays) {
int n = numGrays - 1;
RGB[] colors = new RGB[numGrays];
for (int i = 0; i < numGrays; i++) {
int intensity = (byte)((i * 3) * 256 / n);
colors[i] = new RGB(intensity, intensity, intensity);
}
return new PaletteData(colors);
}
@Override
boolean isFileFormat(LEDataInputStream stream) {
try {
byte[] signature = new byte[3];
stream.read(signature);
stream.unread(signature);
return signature[0] == 'G' && signature[1] == 'I' && signature[2] == 'F';
} catch (Exception e) {
return false;
}
}
/**
* Load the GIF image(s) stored in the input stream.
* Return an array of ImageData representing the image(s).
*/
@Override
ImageData[] loadFromByteStream() {
byte[] signature = new byte[3];
byte[] versionBytes = new byte[3];
byte[] block = new byte[7];
try {
inputStream.read(signature);
if (!(signature[0] == 'G' && signature[1] == 'I' && signature[2] == 'F'))
SWT.error(SWT.ERROR_INVALID_IMAGE);
inputStream.read(versionBytes);
inputStream.read(block);
} catch (IOException e) {
SWT.error(SWT.ERROR_IO, e);
}
screenWidth = (block[0] & 0xFF) | ((block[1] & 0xFF) << 8);
loader.logicalScreenWidth = screenWidth;
screenHeight = (block[2] & 0xFF) | ((block[3] & 0xFF) << 8);
loader.logicalScreenHeight = screenHeight;
byte bitField = block[4];
backgroundPixel = block[5] & 0xFF;
//aspect = block[6] & 0xFF;
bitsPerPixel = ((bitField >> 4) & 0x07) + 1;
defaultDepth = (bitField & 0x7) + 1;
PaletteData palette = null;
if ((bitField & 0x80) != 0) {
// Global palette.
//sorted = (bitField & 0x8) != 0;
palette = readPalette(1 << defaultDepth);
} else {
// No global palette.
//sorted = false;
backgroundPixel = -1;
defaultDepth = bitsPerPixel;
}
loader.backgroundPixel = backgroundPixel;
ImageData[] images = new ImageData[0];
int id = readID();
while (id != GIF_TRAILER_ID && id != -1) {
if (id == GIF_IMAGE_BLOCK_ID) {
ImageData image = readImageBlock(palette);
if (loader.hasListeners()) {
loader.notifyListeners(new ImageLoaderEvent(loader, image, 3, true));
}
ImageData[] oldImages = images;
images = new ImageData[oldImages.length + 1];
System.arraycopy(oldImages, 0, images, 0, oldImages.length);
images[images.length - 1] = image;
} else if (id == GIF_EXTENSION_BLOCK_ID) {
/* Read the extension block. Currently, only the
* interesting parts of certain extensions are kept,
* and the rest is discarded. In future, if we want
* to keep extensions, they should be grouped with
* the image data before which they appear.
*/
readExtension();
} else {
/* The GIF is not to spec, but try to salvage it
* if we read at least one image. */
if (images.length > 0) break;
SWT.error(SWT.ERROR_INVALID_IMAGE);
}
id = readID(); // block terminator (0)
if (id == 0) id = readID(); // next block ID (unless we just read it)
}
return images;
}
/**
* Read and return the next block or extension identifier from the file.
*/
int readID() {
try {
return inputStream.read();
} catch (IOException e) {
SWT.error(SWT.ERROR_IO, e);
}
return -1;
}
/**
* Read a control extension.
* Return the extension block data.
*/
byte[] readExtension() {
int extensionID = readID();
if (extensionID == GIF_COMMENT_BLOCK_ID)
return readCommentExtension();
if (extensionID == GIF_PLAIN_TEXT_BLOCK_ID)
return readPlainTextExtension();
if (extensionID == GIF_GRAPHICS_CONTROL_BLOCK_ID)
return readGraphicsControlExtension();
if (extensionID == GIF_APPLICATION_EXTENSION_BLOCK_ID)
return readApplicationExtension();
// Otherwise, we don't recognize the block. If the
// field size is correct, we can just skip over
// the block contents.
try {
int extSize = inputStream.read();
if (extSize < 0) {
SWT.error(SWT.ERROR_INVALID_IMAGE);
}
byte[] ext = new byte[extSize];
inputStream.read(ext, 0, extSize);
return ext;
} catch (IOException e) {
SWT.error(SWT.ERROR_IO, e);
return null;
}
}
/**
* We have just read the Comment extension identifier
* from the input stream. Read in the rest of the comment
* and return it. GIF comment blocks are variable size.
*/
byte[] readCommentExtension() {
try {
byte[] comment = new byte[0];
byte[] block = new byte[255];
int size = inputStream.read();
while ((size > 0) && (inputStream.read(block, 0, size) != -1)) {
byte[] oldComment = comment;
comment = new byte[oldComment.length + size];
System.arraycopy(oldComment, 0, comment, 0, oldComment.length);
System.arraycopy(block, 0, comment, oldComment.length, size);
size = inputStream.read();
}
return comment;
} catch (Exception e) {
SWT.error(SWT.ERROR_IO, e);
return null;
}
}
/**
* We have just read the PlainText extension identifier
* from the input stream. Read in the plain text info and text,
* and return the text. GIF plain text blocks are variable size.
*/
byte[] readPlainTextExtension() {
try {
// Read size of block = 0x0C.
inputStream.read();
// Read the text information (x, y, width, height, colors).
byte[] info = new byte[12];
inputStream.read(info);
// Read the text.
byte[] text = new byte[0];
byte[] block = new byte[255];
int size = inputStream.read();
while ((size > 0) && (inputStream.read(block, 0, size) != -1)) {
byte[] oldText = text;
text = new byte[oldText.length + size];
System.arraycopy(oldText, 0, text, 0, oldText.length);
System.arraycopy(block, 0, text, oldText.length, size);
size = inputStream.read();
}
return text;
} catch (Exception e) {
SWT.error(SWT.ERROR_IO, e);
return null;
}
}
/**
* We have just read the GraphicsControl extension identifier
* from the input stream. Read in the control information, store
* it, and return it.
*/
byte[] readGraphicsControlExtension() {
try {
// Read size of block = 0x04.
inputStream.read();
// Read the control block.
byte[] controlBlock = new byte[4];
inputStream.read(controlBlock);
byte bitField = controlBlock[0];
// Store the user input field.
//userInput = (bitField & 0x02) != 0;
// Store the disposal method.
disposalMethod = (bitField >> 2) & 0x07;
// Store the delay time.
delayTime = (controlBlock[1] & 0xFF) | ((controlBlock[2] & 0xFF) << 8);
// Store the transparent color.
if ((bitField & 0x01) != 0) {
transparentPixel = controlBlock[3] & 0xFF;
} else {
transparentPixel = -1;
}
return controlBlock;
} catch (Exception e) {
SWT.error(SWT.ERROR_IO, e);
return null;
}
}
/**
* We have just read the Application extension identifier
* from the input stream. Read in the rest of the extension,
* look for and store 'number of repeats', and return the data.
*/
byte[] readApplicationExtension() {
try {
// Read block data.
int blockSize = inputStream.read();
byte[] blockData = new byte[blockSize];
inputStream.read(blockData);
// Read application data.
byte[] data = new byte[0];
byte[] block = new byte[255];
int size = inputStream.read();
while ((size > 0) && (inputStream.read(block, 0, size) != -1)) {
byte[] oldData = data;
data = new byte[oldData.length + size];
System.arraycopy(oldData, 0, data, 0, oldData.length);
System.arraycopy(block, 0, data, oldData.length, size);
size = inputStream.read();
}
// Look for the NETSCAPE 'repeat count' field for an animated GIF.
boolean netscape =
blockSize > 7 &&
blockData[0] == 'N' &&
blockData[1] == 'E' &&
blockData[2] == 'T' &&
blockData[3] == 'S' &&
blockData[4] == 'C' &&
blockData[5] == 'A' &&
blockData[6] == 'P' &&
blockData[7] == 'E';
boolean authentic =
blockSize > 10 &&
blockData[8] == '2' &&
blockData[9] == '.' &&
blockData[10] == '0';
if (netscape && authentic && data[0] == 01) { //$NON-NLS-1$ //$NON-NLS-2$
repeatCount = (data[1] & 0xFF) | ((data[2] & 0xFF) << 8);
loader.repeatCount = repeatCount;
}
return data;
} catch (Exception e) {
SWT.error(SWT.ERROR_IO, e);
return null;
}
}
/**
* Return a DeviceIndependentImage representing the
* image block at the current position in the input stream.
* Throw an error if an error occurs.
*/
ImageData readImageBlock(PaletteData defaultPalette) {
int depth;
PaletteData palette;
byte[] block = new byte[9];
try {
inputStream.read(block);
} catch (IOException e) {
SWT.error(SWT.ERROR_IO, e);
}
int left = (block[0] & 0xFF) | ((block[1] & 0xFF) << 8);
int top = (block[2] & 0xFF) | ((block[3] & 0xFF) << 8);
int width = (block[4] & 0xFF) | ((block[5] & 0xFF) << 8);
int height = (block[6] & 0xFF) | ((block[7] & 0xFF) << 8);
byte bitField = block[8];
boolean interlaced = (bitField & 0x40) != 0;
//boolean sorted = (bitField & 0x20) != 0;
if ((bitField & 0x80) != 0) {
// Local palette.
depth = (bitField & 0x7) + 1;
palette = readPalette(1 << depth);
} else {
// No local palette.
depth = defaultDepth;
palette = defaultPalette;
}
/* Work around: Ignore the case where a GIF specifies an
* invalid index for the transparent pixel that is larger
* than the number of entries in the palette. */
if (transparentPixel > 1 << depth) {
transparentPixel = -1;
}
// Promote depth to next highest supported value.
if (!(depth == 1 || depth == 4 || depth == 8)) {
if (depth < 4)
depth = 4;
else
depth = 8;
}
if (palette == null) {
palette = grayRamp(1 << depth);
}
int initialCodeSize = -1;
try {
initialCodeSize = inputStream.read();
} catch (IOException e) {
SWT.error(SWT.ERROR_IO, e);
}
if (initialCodeSize < 0) {
SWT.error(SWT.ERROR_INVALID_IMAGE);
}
ImageData image = ImageData.internal_new(
width,
height,
depth,
palette,
4,
null,
0,
null,
null,
-1,
transparentPixel,
SWT.IMAGE_GIF,
left,
top,
disposalMethod,
delayTime);
LZWCodec codec = new LZWCodec();
codec.decode(inputStream, loader, image, interlaced, initialCodeSize);
return image;
}
/**
* Read a palette from the input stream.
*/
PaletteData readPalette(int numColors) {
byte[] bytes = new byte[numColors * 3];
try {
if (inputStream.read(bytes) != bytes.length)
SWT.error(SWT.ERROR_INVALID_IMAGE);
} catch (IOException e) {
SWT.error(SWT.ERROR_IO, e);
}
RGB[] colors = new RGB[numColors];
for (int i = 0; i < numColors; i++)
colors[i] = new RGB(bytes[i*3] & 0xFF,
bytes[i*3+1] & 0xFF, bytes[i*3+2] & 0xFF);
return new PaletteData(colors);
}
@Override
void unloadIntoByteStream(ImageLoader loader) {
/* Step 1: Acquire GIF parameters. */
ImageData[] data = loader.data;
int frameCount = data.length;
boolean multi = frameCount > 1;
ImageData firstImage = data[0];
int logicalScreenWidth = multi ? loader.logicalScreenWidth : firstImage.width;
int logicalScreenHeight = multi ? loader.logicalScreenHeight : firstImage.height;
int backgroundPixel = loader.backgroundPixel;
int depth = firstImage.depth;
PaletteData palette = firstImage.palette;
RGB[] colors = palette.getRGBs();
short globalTable = 1;
/* Step 2: Check for validity and global/local color map. */
if (!(depth == 1 || depth == 4 || depth == 8)) {
SWT.error(SWT.ERROR_UNSUPPORTED_DEPTH);
}
for (int i=0; i<frameCount; i++) {
if (data[i].palette.isDirect) {
SWT.error(SWT.ERROR_INVALID_IMAGE);
}
if (multi) {
if (!(data[i].height <= logicalScreenHeight && data[i].width <= logicalScreenWidth && data[i].depth == depth)) {
SWT.error(SWT.ERROR_INVALID_IMAGE);
}
if (globalTable == 1) {
RGB rgbs[] = data[i].palette.getRGBs();
if (rgbs.length != colors.length) {
globalTable = 0;
} else {
for (int j=0; j<colors.length; j++) {
if (!(rgbs[j].red == colors[j].red &&
rgbs[j].green == colors[j].green &&
rgbs[j].blue == colors[j].blue))
globalTable = 0;
}
}
}
}
}
try {
/* Step 3: Write the GIF89a Header and Logical Screen Descriptor. */
outputStream.write(GIF89a);
int bitField = globalTable*128 + (depth-1)*16 + depth-1;
outputStream.writeShort((short)logicalScreenWidth);
outputStream.writeShort((short)logicalScreenHeight);
outputStream.write(bitField);
outputStream.write(backgroundPixel);
outputStream.write(0); // Aspect ratio is 1:1
} catch (IOException e) {
SWT.error(SWT.ERROR_IO, e);
}
/* Step 4: Write Global Color Table if applicable. */
if (globalTable == 1) {
writePalette(palette, depth);
}
/* Step 5: Write Application Extension if applicable. */
if (multi) {
int repeatCount = loader.repeatCount;
try {
outputStream.write(GIF_EXTENSION_BLOCK_ID);
outputStream.write(GIF_APPLICATION_EXTENSION_BLOCK_ID);
outputStream.write(NETSCAPE2_0.length);
outputStream.write(NETSCAPE2_0);
outputStream.write(3); // Three bytes follow
outputStream.write(1); // Extension type
outputStream.writeShort((short) repeatCount);
outputStream.write(0); // Block terminator
} catch (IOException e) {
SWT.error(SWT.ERROR_IO, e);
}
}
for (int frame=0; frame<frameCount; frame++) {
/* Step 6: Write Graphics Control Block for each frame if applicable. */
if (multi || data[frame].transparentPixel != -1) {
writeGraphicsControlBlock(data[frame]);
}
/* Step 7: Write Image Header for each frame. */
int x = data[frame].x;
int y = data[frame].y;
int width = data[frame].width;
int height = data[frame].height;
try {
outputStream.write(GIF_IMAGE_BLOCK_ID);
byte[] block = new byte[9];
block[0] = (byte)(x & 0xFF);
block[1] = (byte)((x >> 8) & 0xFF);
block[2] = (byte)(y & 0xFF);
block[3] = (byte)((y >> 8) & 0xFF);
block[4] = (byte)(width & 0xFF);
block[5] = (byte)((width >> 8) & 0xFF);
block[6] = (byte)(height & 0xFF);
block[7] = (byte)((height >> 8) & 0xFF);
block[8] = (byte)(globalTable == 0 ? (depth-1) | 0x80 : 0x00);
outputStream.write(block);
} catch (IOException e) {
SWT.error(SWT.ERROR_IO, e);
}
/* Step 8: Write Local Color Table for each frame if applicable. */
if (globalTable == 0) {
writePalette(data[frame].palette, depth);
}
/* Step 9: Write the actual data for each frame. */
try {
outputStream.write(depth); // Minimum LZW Code size
} catch (IOException e) {
SWT.error(SWT.ERROR_IO, e);
}
new LZWCodec().encode(outputStream, data[frame]);
}
/* Step 10: Write GIF terminator. */
try {
outputStream.write(0x3B);
} catch (IOException e) {
SWT.error(SWT.ERROR_IO, e);
}
}
/**
* Write out a GraphicsControlBlock to describe
* the specified device independent image.
*/
void writeGraphicsControlBlock(ImageData image) {
try {
outputStream.write(GIF_EXTENSION_BLOCK_ID);
outputStream.write(GIF_GRAPHICS_CONTROL_BLOCK_ID);
byte[] gcBlock = new byte[4];
gcBlock[0] = 0;
gcBlock[1] = 0;
gcBlock[2] = 0;
gcBlock[3] = 0;
if (image.transparentPixel != -1) {
gcBlock[0] = (byte)0x01;
gcBlock[3] = (byte)image.transparentPixel;
}
if (image.disposalMethod != 0) {
gcBlock[0] |= (byte)((image.disposalMethod & 0x07) << 2);
}
if (image.delayTime != 0) {
gcBlock[1] = (byte)(image.delayTime & 0xFF);
gcBlock[2] = (byte)((image.delayTime >> 8) & 0xFF);
}
outputStream.write((byte)gcBlock.length);
outputStream.write(gcBlock);
outputStream.write(0); // Block terminator
} catch (IOException e) {
SWT.error(SWT.ERROR_IO, e);
}
}
/**
* Write the specified palette to the output stream.
*/
void writePalette(PaletteData palette, int depth) {
byte[] bytes = new byte[(1 << depth) * 3];
int offset = 0;
for (int i = 0; i < palette.colors.length; i++) {
RGB color = palette.colors[i];
bytes[offset] = (byte)color.red;
bytes[offset + 1] = (byte)color.green;
bytes[offset + 2] = (byte)color.blue;
offset += 3;
}
try {
outputStream.write(bytes);
} catch (IOException e) {
SWT.error(SWT.ERROR_IO, e);
}
}
}