android 开发对gif解码（适配android 4.2、4.3、4.4版本）
使用方法：
public class ImageInputActivity extends Activity implements GifAction{
...
/**
* 解码之后得到的结果，实现接口
*/
@Override
public void parseOk(boolean parseStatus, int frameIndex) {
int size = gifDecoder2.getFrameCount();
Log.v("parseOk", "gifDecoder2 size=="+size+";frameIndex="+frameIndex+";parseStatus="+parseStatus);
if (frameIndex == -1) { //只有当-1的时候才说明解码完成，否则会解析得到一帧就会调用一次
for (int i = 0; i <= gifDecoder2.getFrameCount(); i++) {
com.xlm.testgif.gif.GifFrame frame = gifDecoder2.next();
// currentImage = frame.image;
// int delay = frame.delay;
// addFrame(new BitmapDrawable(currentImage), delay);
ImageView iv_image = new ImageView(CustomActivity.this);
iv_image.setPadding(5, 5, 5, 5);
LayoutParams lparams = new LayoutParams(100, 100);
iv_image.setLayoutParams(lparams);
iv_image.setBackgroundColor(Color.BLUE);
iv_image.setImageBitmap(frame.image);
ll_decodeimages.addView(iv_image);
}
}
}
gif解码源码：
GifDecoder
package com.xlm.testgif.gif; import java.io.ByteArrayInputStream;
import java.io.InputStream; import android.graphics.Bitmap;
import android.graphics.Bitmap.Config; public class GifDecoder implements Runnable{ public static final int STATUS_PARSING = 0;
public static final int STATUS_FORMAT_ERROR = 1;
public static final int STATUS_OPEN_ERROR = 2;
public static final int STATUS_FINISH = -1; private InputStream in;
private int status; public int width; // full image width
public int height; // full image height
private boolean gctFlag; // global color table used
private int gctSize; // size of global color table
private int loopCount = 1; // iterations; 0 = repeat forever private int[] gct; // global color table
private int[] lct; // local color table
private int[] act; // active color table private int bgIndex; // background color index
private int bgColor; // background color
private int lastBgColor; // previous bg color
private int pixelAspect; // pixel aspect ratio private boolean lctFlag; // local color table flag
private boolean interlace; // interlace flag
private int lctSize; // local color table size private int ix, iy, iw, ih; // current image rectangle
private int lrx, lry, lrw, lrh;
private Bitmap image; // current frame
private Bitmap lastImage; // previous frame
private GifFrame currentFrame = null; private boolean isShow = false; private byte[] block = new byte[256]; // current data block
private int blockSize = 0; // block size // last graphic control extension info
private int dispose = 0;
// 0=no action; 1=leave in place; 2=restore to bg; 3=restore to prev
private int lastDispose = 0;
private boolean transparency = false; // use transparent color
private int delay = 0; // delay in milliseconds
private int transIndex; // transparent color index private static final int MaxStackSize = 4096;
// max decoder pixel stack size // LZW decoder working arrays
private short[] prefix;
private byte[] suffix;
private byte[] pixelStack;
private byte[] pixels; private GifFrame gifFrame; // frames read from current file
private int frameCount; private GifAction action = null; private byte[] gifData = null; public GifDecoder(byte[] data,GifAction act){
gifData = data;
action = act;
} public GifDecoder(InputStream is,GifAction act){
in = is;
action = act;
} public void run(){
if(in != null){
readStream();
}else if(gifData != null){
readByte();
}
} /**
* 锟酵凤拷锟斤拷源
*/
public void free(){
GifFrame fg = gifFrame;
while(fg != null){
fg.image = null;
fg = null;
gifFrame = gifFrame.nextFrame;
fg = gifFrame;
}
if(in != null){
try{
in.close();
}catch(Exception ex){}
in = null;
}
gifData = null;
} /**
* 锟斤拷前状态
* @return
*/
public int getStatus(){
return status;
} /**
* 锟斤拷锟斤拷锟角凤拷晒锟斤拷锟斤拷晒锟斤拷锟斤拷锟絫rue
* @return 锟缴癸拷锟斤拷锟斤拷true锟斤拷锟斤拷锟津返伙拷false
*/
public boolean parseOk(){
return status == STATUS_FINISH;
} /**
* 取某帧锟斤拷锟斤拷时时锟斤拷
* @param n 锟节硷拷帧
* @return 锟斤拷时时锟戒，锟斤拷锟斤拷
*/
public int getDelay(int n) {
delay = -1;
if ((n >= 0) && (n < frameCount)) {
// delay = ((GifFrame) frames.elementAt(n)).delay;
GifFrame f = getFrame(n);
if (f != null)
delay = f.delay;
}
return delay;
} /**
* 取锟斤拷锟斤拷帧锟斤拷锟斤拷时时锟斤拷
* @return
*/
public int[] getDelays(){
GifFrame f = gifFrame;
int[] d = new int[frameCount];
int i = 0;
while(f != null && i < frameCount){
d[i] = f.delay;
f = f.nextFrame;
i++;
}
return d;
} /**
* 取锟斤拷帧 锟斤拷
* @return 图片锟斤拷锟斤拷帧锟斤拷
*/
public int getFrameCount() {
return frameCount;
} /**
* 取锟斤拷一帧图片
* @return
*/
public Bitmap getImage() {
return getFrameImage(0);
} public int getLoopCount() {
return loopCount;
} private void setPixels() {
int[] dest = new int[width * height];
// 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 = getFrameImage(n - 1);
} else {
lastImage = null;
}
}
if (lastImage != null) {
lastImage.getPixels(dest, 0, width, 0, 0, width, height);
// copy pixels
if (lastDispose == 2) {
// fill last image rect area with background color
int c = 0;
if (!transparency) {
c = lastBgColor;
}
for (int i = 0; i < lrh; i++) {
int n1 = (lry + i) * width + lrx;
int n2 = n1 + lrw;
for (int k = n1; k < n2; k++) {
dest[k] = c;
}
}
}
}
} // 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 = ((int) pixels[sx++]) & 0xff;
int c = act[index];
if (c != 0) {
dest[dx] = c;
}
dx++;
}
}
}
image = Bitmap.createBitmap(dest, width, height, Config.ARGB_4444);
} /**
* 取锟节硷拷帧锟斤拷图片
* @param n 帧锟斤拷
* @return 锟缴伙拷锟斤拷图片锟斤拷锟斤拷锟矫伙拷写锟街★拷锟斤拷叱锟斤拷?锟斤拷锟斤拷null
*/
public Bitmap getFrameImage(int n) {
GifFrame frame = getFrame(n);
if (frame == null)
return null;
else
return frame.image;
} /**
* 取锟斤拷前帧图片
* @return 锟斤拷前帧锟缴伙拷锟斤拷图片
*/
public GifFrame getCurrentFrame(){
return currentFrame;
} /**
* 取锟节硷拷帧锟斤拷每帧锟斤拷锟剿可伙拷锟斤拷图片锟斤拷锟斤拷时时锟斤拷
* @param n 帧锟斤拷
* @return
*/
public GifFrame getFrame(int n) {
GifFrame frame = gifFrame;
int i = 0;
while (frame != null) {
if (i == n) {
return frame;
} else {
frame = frame.nextFrame;
}
i++;
}
return null;
} /**
* 锟斤拷锟矫ｏ拷锟斤拷锟叫憋拷锟斤拷锟斤拷锟襟，伙拷直锟接碉拷锟斤拷一帧
*/
public void reset(){
currentFrame = gifFrame;
} /**
* 锟斤拷一帧锟斤拷锟斤拷锟叫憋拷锟斤拷锟斤拷锟斤拷通锟斤拷getCurrentFrame锟矫碉拷锟斤拷锟斤拷锟斤拷一帧
* @return 锟斤拷锟斤拷锟斤拷一帧
*/
public GifFrame next() {
if(isShow == false){
isShow = true;
return gifFrame;
}else{
if(status == STATUS_PARSING){
if(currentFrame.nextFrame != null)
currentFrame = currentFrame.nextFrame;
//currentFrame = gifFrame;
}else{
currentFrame = currentFrame.nextFrame;
if (currentFrame == null) {
currentFrame = gifFrame;
}
}
return currentFrame;
}
} private int readByte(){
in = new ByteArrayInputStream(gifData);
gifData = null;
return readStream();
} // public int read(byte[] data){
// InputStream is = new ByteArrayInputStream(data);
// return read(is);
// } private int readStream(){
init();
if(in != null){
readHeader();
if(!err()){
readContents();
if(frameCount < 0){
status = STATUS_FORMAT_ERROR;
action.parseOk(false,-1);
}else{
status = STATUS_FINISH;
action.parseOk(true,-1);
}
}
try {
in.close();
} catch (Exception e) {
e.printStackTrace();
} }else {
status = STATUS_OPEN_ERROR;
action.parseOk(false,-1);
}
return status;
} private 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 += (((int) 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 = ((int) 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
}
} private boolean err() {
return status != STATUS_PARSING;
} private void init() {
status = STATUS_PARSING;
frameCount = 0;
gifFrame = null;
gct = null;
lct = null;
} private int read() {
int curByte = 0;
try { curByte = in.read();
} catch (Exception e) {
status = STATUS_FORMAT_ERROR;
}
return curByte;
} private 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 (Exception e) {
e.printStackTrace();
}
if (n < blockSize) {
status = STATUS_FORMAT_ERROR;
}
}
return n;
} private 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 (Exception e) {
e.printStackTrace();
}
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 = ((int) c[j++]) & 0xff;
int g = ((int) c[j++]) & 0xff;
int b = ((int) c[j++]) & 0xff;
tab[i++] = 0xff000000 | (r << 16) | (g << 8) | b;
}
}
return tab;
} private 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 = "";
for (int i = 0; i < 11; i++) {
app += (char) block[i];
}
if (app.equals("NETSCAPE2.0")) {
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;
}
}
} private 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
} private 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];
}
} private 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 = Bitmap.createBitmap(width, height, Config.ARGB_4444);
// createImage(width, height);
setPixels(); // transfer pixel data to image
if (gifFrame == null) {
gifFrame = new GifFrame(image, delay);
currentFrame = gifFrame;
} else {
GifFrame f = gifFrame;
while(f.nextFrame != null){
f = f.nextFrame;
}
f.nextFrame = new GifFrame(image, delay);
}
// frames.addElement(new GifFrame(image, delay)); // add image to frame
// list
if (transparency) {
act[transIndex] = save;
}
resetFrame();
action.parseOk(true, frameCount);
} private 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
setPixelAspect(read()); // pixel aspect ratio
} private void readNetscapeExt() {
do {
readBlock();
if (block[0] == 1) {
// loop count sub-block
int b1 = ((int) block[1]) & 0xff;
int b2 = ((int) block[2]) & 0xff;
loopCount = (b2 << 8) | b1;
}
} while ((blockSize > 0) && !err());
} private int readShort() {
// read 16-bit value, LSB first
return read() | (read() << 8);
} private void resetFrame() {
lastDispose = dispose;
lrx = ix;
lry = iy;
lrw = iw;
lrh = ih;
lastImage = image;
lastBgColor = bgColor;
dispose = 0;
transparency = false;
delay = 0;
lct = null;
} /**
* Skips variable length blocks up to and including next zero length block.
*/
private void skip() {
do {
readBlock();
} while ((blockSize > 0) && !err());
} public int getPixelAspect() {
return pixelAspect;
} public void setPixelAspect(int pixelAspect) {
this.pixelAspect = pixelAspect;
}
}
GifFrame
import android.graphics.Bitmap;
public class GifFrame {
public Bitmap image;
public int delay;
public GifFrame nextFrame = null;
public GifFrame(Bitmap im, int del) {
image = im;
delay = del;
}
}
GifAction
public abstract interface GifAction {
/**
* gif 接口
* @param parseStatus 解析成功true
* @param frameIndex -1时说明已经全部解析完成，当大于0时为解析得到的gif帧编号
*/
public abstract void parseOk(boolean parseStatus,int frameIndex);
}