android 开发对gif解码（适配android 4.2、4.3、4.4版本）

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);
}