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J2ME中的GIF处理类
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  发一个GIF处理的类,可以减少图片资源,不需要太多的png了

  用法如下:

private GIFDecode gifd;
private int ind;
private int gifCount;
private Image frame;
void initGIF() {
 gifd = new GIFDecode();
 gifd.read(this.getClass().getResourceAsStream("/ar.gif"));//载入gif图片
 ind = 0;
 gifCount = gifd.getFrameCount();//获得帧数
 System.out.println("gifCount="+gifCount);
}
void drawProgressBar(Graphics g, int xpos, int ypos, int anchor) {
 frame = gifd.getFrame(ind);
 ind++;
 if (ind >= gifCount) {
 ind = 0;
 }
 g.drawImage(frame, xpos, ypos, anchor);//循环绘图
}
//////////////////////////////////////////////////////////////////////////////////
import java.util.Vector;
import java.io.InputStream;
import javax.microedition.lcdui.Image;
public class GIFDecode {
  /**
   * 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;
  protected InputStream in;
  protected int status;
  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[] lct; // local color table
  protected int[] act; // active color table
  protected int bgIndex; // background color index
  protected int bgColor; // background color
  protected int lastBgColor; // previous bg color
  protected int pixelAspect; // pixel aspect ratio
  protected boolean lctFlag; // local color table flag
  protected boolean interlace; // interlace flag
  protected int lctSize; // local color table size
  protected int ix, iy, iw, ih; // current image rectangle
  protected int lrx, lry, lrw, lrh;
  protected Image image; // current frame
  protected Image lastImage; // previous frame
  protected byte[] block = new byte[256]; // current data block
  protected int blockSize = 0; // block size
  // last graphic control extension info
  protected int dispose = 0;
  // 0=no action; 1=leave in place; 2=restore to bg; 3=restore to prev
  protected int lastDispose = 0;
  protected boolean transparency = false; // use transparent color
  protected int delay = 0; // delay in milliseconds
  protected int transIndex; // transparent color index
  protected static final int MaxStackSize = 4096;
  // max decoder pixel stack size
  // LZW decoder working arrays
  protected short[] prefix;
  protected byte[] suffix;
  protected byte[] pixelStack;
  protected byte[] pixels;
  protected Vector frames; // frames read from current file
  protected int frameCount;
  static class GifFrame {
    public GifFrame(Image im, int del) {
      image = im;
      delay = del;
    }
    public Image image;
    public int delay;
  }
  /**
   * Gets display duration for specified frame.
   *
   * @param n
   *      int index of frame
   * @return delay in milliseconds
   */
  public int getDelay(int n) {
<   delay = -1;
    if ((n >= 0) && (n < frameCount)) {
      delay = ((GifFrame) frames.elementAt(n)).delay;
    }
    return delay;
  }
  /**
   * Gets the number of frames read from file.
   *
   * @return frame count
   */
  public int getFrameCount() {
    return frameCount;
  }
  /**
   * Gets the first (or only) image read.
   *
   * @return BufferedImage containing first frame, or null if none.
   */
  public Image getImage() {
    return getFrame(0);
  }
  /**
   * 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;
  }
  /**
   * Creates new frame image from current data (and previous frames as
   * specified by their disposition codes).
   */
  protected void setPixels() {
    // expose destination image's pixels as int array
    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 = getFrame(n - 1);
        } else {
          lastImage = null;
        }
      }
      if (lastImage != null) {
        lastImage.getRGB(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 = Image.createRGBImage(dest, width, height, false);
  }
  /**
   * Gets the image contents of frame n.
   *
   * @return BufferedImage representation of frame, or null if n is invalid.
   */
  public Image getFrame(int n) {
    Image im = null;
    if ((n >= 0) && (n < frameCount)) {
      im = ((GifFrame) frames.elementAt(n)).image;
    }
    return im;
  }
  /**
   * Reads GIF image from stream
   *
   * @param BufferedInputStream
   *      containing GIF file.
   * @return read status code (0 = no errors)
   */
  public int read(InputStream is) {
    init();
    if (is != null) {
      in = is;
      readHeader();
      if (!err()) {
        readContents();
        if (frameCount < 0) {
          status = STATUS_FORMAT_ERROR;
        }
      }
    } else {
      status = STATUS_OPEN_ERROR;
    }
    try {
      is.close();
    } catch (Exception e) {
      e.printStackTrace();
    }
    return status;
  }
  /**
   * Decodes LZW image data into pixel array. Adapted from John Cristy's
   * ImageMagick.
   */
  protected 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)

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