/**
* Copyright (c) 2013 Xcellent Creations, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package com.mycom.lib.gifimageview;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.BufferUnderflowException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.ArrayList;
import android.graphics.Bitmap;
import android.util.Log;
/**
* Reads frame data from a GIF image source and decodes it into individual frames
* for animation purposes. Image data can be read from either and InputStream source
* or a byte[].
*
* This class is optimized for running animations with the frames, there
* are no methods to get individual frame images, only to decode the next frame in the
* animation sequence. Instead, it lowers its memory footprint by only housing the minimum
* data necessary to decode the next frame in the animation sequence.
*
* The animation must be manually moved forward using {@link #advance()} before requesting the next
* frame. This method must also be called before you request the first frame or an error will
* occur.
*
* Implementation adapted from sample code published in Lyons. (2004). <em>Java for Programmers</em>,
* republished under the MIT Open Source License
*/
public class GifDecoder {
private static final String TAG = GifDecoder.class.getSimpleName();
/**
* 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;
/**
* max decoder pixel stack size
*/
protected static final int MAX_STACK_SIZE = 4096;
/**
* GIF Disposal Method meaning take no action
*/
private static final int DISPOSAL_UNSPECIFIED = 0;
/**
* GIF Disposal Method meaning leave canvas from previous frame
*/
private static final int DISPOSAL_NONE = 1;
/**
* GIF Disposal Method meaning clear canvas to background color
*/
private static final int DISPOSAL_BACKGROUND = 2;
/**
* GIF Disposal Method meaning clear canvas to frame before last
*/
private static final int DISPOSAL_PREVIOUS = 3;
/**
* Global status code of GIF data parsing
*/
protected int status;
// Global File Header values and parsing flags
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[] act; // active color table
protected int bgIndex; // background color index
protected int bgColor; // background color
protected int pixelAspect; // pixel aspect ratio
protected boolean lctFlag; // local color table flag
protected int lctSize; // local color table size
// Raw GIF data from input source
protected ByteBuffer rawData;
// Raw data read working array
protected byte[] block = new byte[256]; // current data block
protected int blockSize = 0; // block size last graphic control extension info
// LZW decoder working arrays
protected short[] prefix;
protected byte[] suffix;
protected byte[] pixelStack;
protected byte[] mainPixels;
protected int[] mainScratch, copyScratch;
protected ArrayList<GifFrame> frames; // frames read from current file
protected GifFrame currentFrame;
protected Bitmap previousImage, currentImage, renderImage;
protected int framePointer;
protected int frameCount;
/**
* Inner model class housing metadata for each frame
*/
private static class GifFrame {
public int ix, iy, iw, ih;
/* Control Flags */
public boolean interlace;
public boolean transparency;
/* Disposal Method */
public int dispose;
/* Transparency Index */
public int transIndex;
/* Delay, in ms, to next frame */
public int delay;
/* Index in the raw buffer where we need to start reading to decode */
public int bufferFrameStart;
/* Local Color Table */
public int[] lct;
}
/**
* Move the animation frame counter forward
*/
public void advance() {
if (frameCount > 0)
framePointer = (framePointer + 1) % frameCount;
}
/**
* Gets display duration for specified frame.
*
* @param n int index of frame
* @return delay in milliseconds
*/
public int getDelay(final int n) {
int delay = 0;
if ((n >= 0) && (n < frameCount)) {
delay = frames.get(n).delay;
}
return delay;
}
/**
* Gets display duration for the upcoming frame
*/
public int getNextDelay() {
if (frameCount <= 0 || framePointer < 0) {
return 0;
}
return getDelay(framePointer);
}
/**
* Gets the number of frames read from file.
*
* @return frame count
*/
public int getFrameCount() {
return frameCount;
}
/**
* Gets the current index of the animation frame, or -1 if animation hasn't not yet started
*
* @return frame index
*/
public int getCurrentFrameIndex() {
return framePointer;
}
/**
* 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;
}
/**
* Get the next frame in the animation sequence.
*
* @return Bitmap representation of frame
*/
public Bitmap getNextFrame() {
if (frameCount <= 0 || framePointer < 0 || currentImage == null) {
return null;
}
final GifFrame frame = frames.get(framePointer);
// Set the appropriate color table
if (frame.lct == null) {
act = gct;
} else {
act = frame.lct;
if (bgIndex == frame.transIndex) {
bgColor = 0;
}
}
int save = 0;
if (frame.transparency) {
save = act[frame.transIndex];
act[frame.transIndex] = 0; // set transparent color if specified
}
if (act == null) {
Log.w(TAG, "No Valid Color Table");
status = STATUS_FORMAT_ERROR; // no color table defined
return null;
}
setPixels(framePointer); // transfer pixel data to image
// Reset the transparent pixel in the color table
if (frame.transparency) {
act[frame.transIndex] = save;
}
return currentImage;
}
/**
* Reads GIF image from stream
*
* @param is containing GIF file.
* @return read status code (0 = no errors)
*/
public int read(final InputStream is, final int contentLength) {
if (is != null) {
try {
final int capacity = (contentLength > 0) ? (contentLength + 4096) : 4096;
final ByteArrayOutputStream buffer = new ByteArrayOutputStream(capacity);
int nRead;
final byte[] data = new byte[16384];
while ((nRead = is.read(data, 0, data.length)) != -1) {
buffer.write(data, 0, nRead);
}
buffer.flush();
read(buffer.toByteArray());
} catch (final IOException e) {
Log.w(TAG, "Error reading data from stream", e);
}
} else {
status = STATUS_OPEN_ERROR;
}
try {
is.close();
} catch (final Exception e) {
Log.w(TAG, "Error closing stream", e);
}
return status;
}
/**
* Reads GIF image from byte array
*
* @param data containing GIF file.
* @return read status code (0 = no errors)
*/
public int read(final byte[] data) {
init();
if (data != null) {
// Initiliaze the raw data buffer
rawData = ByteBuffer.wrap(data);
rawData.rewind();
rawData.order(ByteOrder.LITTLE_ENDIAN);
readHeader();
if (!err()) {
readContents();
if (frameCount < 0) {
status = STATUS_FORMAT_ERROR;
}
}
} else {
status = STATUS_OPEN_ERROR;
}
return status;
}
/**
* Creates new frame image from current data (and previous frames as specified by their disposition codes).
*/
protected void setPixels(final int frameIndex) {
final GifFrame currentFrame = frames.get(frameIndex);
GifFrame previousFrame = null;
final int previousIndex = frameIndex - 1;
if (previousIndex >= 0) {
previousFrame = frames.get(previousIndex);
}
// final location of blended pixels
final int[] dest = mainScratch;
// fill in starting image contents based on last image's dispose code
if (previousFrame != null && previousFrame.dispose > DISPOSAL_UNSPECIFIED) {
if (previousFrame.dispose == DISPOSAL_NONE && currentImage != null) {
// Start with the current image
currentImage.getPixels(dest, 0, width, 0, 0, width, height);
}
if (previousFrame.dispose == DISPOSAL_BACKGROUND) {
// Start with a canvas filled with the background color
int c = 0;
if (!currentFrame.transparency) {
c = bgColor;
}
for (int i = 0; i < previousFrame.ih; i++) {
final int n1 = (previousFrame.iy + i) * width + previousFrame.ix;
final int n2 = n1 + previousFrame.iw;
for (int k = n1; k < n2; k++) {
dest[k] = c;
}
}
}
if (previousFrame.dispose == DISPOSAL_PREVIOUS && previousImage != null) {
// Start with the previous frame
previousImage.getPixels(dest, 0, width, 0, 0, width, height);
}
}
// Decode pixels for this frame into the global pixels[] scratch
decodeBitmapData(currentFrame, mainPixels); // decode pixel data
// 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 < currentFrame.ih; i++) {
int line = i;
if (currentFrame.interlace) {
if (iline >= currentFrame.ih) {
pass++;
switch (pass) {
case 2:
iline = 4;
break;
case 3:
iline = 2;
inc = 4;
break;
case 4:
iline = 1;
inc = 2;
break;
default:
break;
}
}
line = iline;
iline += inc;
}
line += currentFrame.iy;
if (line < height) {
final int k = line * width;
int dx = k + currentFrame.ix; // start of line in dest
int dlim = dx + currentFrame.iw; // end of dest line
if ((k + width) < dlim) {
dlim = k + width; // past dest edge
}
int sx = i * currentFrame.iw; // start of line in source
while (dx < dlim) {
// map color and insert in destination
final int index = (mainPixels[sx++]) & 0xff;
final int c = act[index];
if (c != 0) {
dest[dx] = c;
}
dx++;
}
}
}
// Copy pixels into previous image
currentImage.getPixels(copyScratch, 0, width, 0, 0, width, height);
previousImage.setPixels(copyScratch, 0, width, 0, 0, width, height);
// Set pixels for current image
currentImage.setPixels(dest, 0, width, 0, 0, width, height);
}
/**
* Decodes LZW image data into pixel array. Adapted from John Cristy's BitmapMagick.
*/
protected void decodeBitmapData(final GifFrame frame, byte[] dstPixels) {
if (frame != null) {
// Jump to the frame start position
rawData.position(frame.bufferFrameStart);
}
final int nullCode = -1;
final int npix = (frame == null) ? width * height : frame.iw * frame.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 (dstPixels == null || dstPixels.length < npix) {
dstPixels = new byte[npix]; // allocate new pixel array
}
if (prefix == null) {
prefix = new short[MAX_STACK_SIZE];
}
if (suffix == null) {
suffix = new byte[MAX_STACK_SIZE];
}
if (pixelStack == null) {
pixelStack = new byte[MAX_STACK_SIZE + 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; // XXX ArrayIndexOutOfBoundsException
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 >= MAX_STACK_SIZE) {
break;
}
pixelStack[top++] = (byte)first;
prefix[available] = (short)old_code;
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--;
dstPixels[pi++] = pixelStack[top];
i++;
}
for (i = pi; i < npix; i++) {
dstPixels[i] = 0; // clear missing pixels
}
}
/**
* Returns true if an error was encountered during reading/decoding
*/
protected boolean err() {
return status != STATUS_OK;
}
/**
* Initializes or re-initializes reader
*/
protected void init() {
status = STATUS_OK;
frameCount = 0;
framePointer = -1;
frames = new ArrayList<GifFrame>();
gct = null;
}
/**
* Reads a single byte from the input stream.
*/
protected int read() {
int curByte = 0;
try {
curByte = (rawData.get() & 0xFF);
} catch (final Exception 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;
while (n < blockSize) {
count = blockSize - n;
rawData.get(block, n, count);
n += count;
}
} catch (final Exception e) {
Log.w(TAG, "Error Reading Block", e);
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(final int ncolors) {
final int nbytes = 3 * ncolors;
int[] tab = null;
final byte[] c = new byte[nbytes];
try {
rawData.get(c);
tab = new int[256]; // max size to avoid bounds checks
int i = 0;
int j = 0;
while (i < ncolors) {
final int r = (c[j++]) & 0xff;
final int g = (c[j++]) & 0xff;
final int b = (c[j++]) & 0xff;
tab[i++] = 0xff000000 | (r << 16) | (g << 8) | b;
}
} catch (final BufferUnderflowException e) {
Log.w(TAG, "Format Error Reading Color Table", e);
status = STATUS_FORMAT_ERROR;
}
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
readBitmap();
break;
case 0x21: // extension
code = read();
switch (code) {
case 0xf9: // graphics control extension
// Start a new frame
currentFrame = new GifFrame();
readGraphicControlExt();
break;
case 0xff: // application extension
readBlock();
String app = "";
for (int i = 0; i < 11; i++) {
app += (char)block[i];
}
if (app.equals("NETSCAPE2.0")) {
readNetscapeExt();
} else {
skip(); // don't care
}
break;
case 0xfe:// comment extension
skip();
break;
case 0x01:// plain text extension
skip();
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 GIF file header information.
*/
protected void readHeader() {
String id = "";
for (int i = 0; i < 6; i++) {
id += (char)read();
}
if (!id.startsWith("GIF")) {
status = STATUS_FORMAT_ERROR;
return;
}
readLSD();
if (gctFlag && !err()) {
gct = readColorTable(gctSize);
bgColor = gct[bgIndex];
}
}
/**
* Reads Graphics Control Extension values
*/
protected void readGraphicControlExt() {
read(); // block size
final int packed = read(); // packed fields
currentFrame.dispose = (packed & 0x1c) >> 2; // disposal method
if (currentFrame.dispose == 0) {
currentFrame.dispose = 1; // elect to keep old image if discretionary
}
currentFrame.transparency = (packed & 1) != 0;
currentFrame.delay = readShort() * 10; // delay in milliseconds
currentFrame.transIndex = read(); // transparent color index
read(); // block terminator
}
/**
* Reads next frame image
*/
protected void readBitmap() {
currentFrame.ix = readShort(); // (sub)image position & size
currentFrame.iy = readShort();
currentFrame.iw = readShort();
currentFrame.ih = readShort();
final int packed = read();
lctFlag = (packed & 0x80) != 0; // 1 - local color table flag interlace
lctSize = (int)Math.pow(2, (packed & 0x07) + 1);
// 3 - sort flag
// 4-5 - reserved lctSize = 2 << (packed & 7); // 6-8 - local color
// table size
currentFrame.interlace = (packed & 0x40) != 0;
if (lctFlag) {
currentFrame.lct = readColorTable(lctSize); // read table
} else {
currentFrame.lct = null; // No local color table
}
currentFrame.bufferFrameStart = rawData.position(); // Save this as the decoding position pointer
skipBitmapData();
if (err()) {
return;
}
frameCount++;
frames.add(currentFrame); // add image to frame
}
private void skipBitmapData() {
read(); // code size
skip();
}
/**
* Reads Logical Screen Descriptor
*/
protected void readLSD() {
// logical screen size
width = readShort();
height = readShort();
// packed fields
final 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
// Now that we know the size, init scratch arrays
try {
mainPixels = new byte[width * height];
mainScratch = new int[width * height];
copyScratch = new int[width * height];
previousImage = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);
currentImage = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);
} catch (final OutOfMemoryError e) {
// Try with halving down the bitmap size
final int dimension = (width * height) / 2;
mainPixels = new byte[dimension];
mainScratch = new int[dimension];
copyScratch = new int[dimension];
previousImage = Bitmap.createBitmap(width / 2, height / 2, Bitmap.Config.RGB_565);
currentImage = Bitmap.createBitmap(width / 2, height / 2, Bitmap.Config.RGB_565);
}
}
/**
* Reads Netscape extenstion to obtain iteration count
*/
protected void readNetscapeExt() {
do {
readBlock();
if (block[0] == 1) {
// loop count sub-block
final int b1 = (block[1]) & 0xff;
final int b2 = (block[2]) & 0xff;
loopCount = (b2 << 8) | b1;
}
} while ((blockSize > 0) && !err());
}
/**
* Reads next 16-bit value, LSB first
*/
protected int readShort() {
// read 16-bit value
return rawData.getShort();
}
/**
* Skips variable length blocks up to and including next zero length block.
*/
protected void skip() {
do {
readBlock();
} while ((blockSize > 0) && !err());
}
}