java生成gif

package com.lh.utils; import java.net.*; import java.io.*; import java.util.*; import java.awt.*; import java.awt.image.*; /** * Class GifDecoder - Decodes a GIF file into one or more frames. * <br><pre> * Example: * GifDecoder d = new GifDecoder(); * d.read("sample.gif"); * int n = d.getFrameCount(); * for (int i = 0; i < n; i++) { * BufferedImage frame = d.getFrame(i); // frame i * int t = d.getDelay(i); // display duration of frame in milliseconds * // do something with frame * } * </pre> * No copyright asserted on the source code of this class. May be used for * any purpose, however, refer to the Unisys LZW patent for any additional * restrictions. Please forward any corrections to questions at fmsware.com. * * @author Kevin Weiner, FM Software; LZW decoder adapted from John Cristy's ImageMagick. * @version 1.03 November 2003 * */ public class GifDecoder { /** * 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 BufferedInputStream 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 Rectangle lastRect; // last image rect protected BufferedImage image; // current frame protected BufferedImage 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 ArrayList frames; // frames read from current file protected int frameCount; static class GifFrame { public GifFrame(BufferedImage im, int del) { image = im; delay = del; } public BufferedImage 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.get(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 BufferedImage 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 = ((DataBufferInt) image.getRaster().getDataBuffer()).getData(); // 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) { int[] prev = ((DataBufferInt) lastImage.getRaster().getDataBuffer()).getData(); System.arraycopy(prev, 0, dest, 0, width * height); // copy pixels if (lastDispose == 2) { // fill last image rect area with background color Graphics2D g = image.createGraphics(); Color c = null; if (transparency) { c = new Color(0, 0, 0, 0); // assume background is transparent } else { c = new Color(lastBgColor); // use given background color } g.setColor(c); g.setComposite(AlphaComposite.Src); // replace area g.fill(lastRect); g.dispose(); } } } // 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++; } } } } /** * Gets the image contents of frame n. * * @return BufferedImage representation of frame, or null if n is invalid. */ public BufferedImage getFrame(int n) { BufferedImage im = null; if ((n >= 0) && (n < frameCount)) { im = ((GifFrame) frames.get(n)).image; } return im; } /** * Gets image size. * * @return GIF image dimensions */ public Dimension getFrameSize() { return new Dimension(width, height); } /** * Reads GIF image from stream * * @param BufferedInputStream containing GIF file. * @return read status code (0 = no errors) */ public int read(BufferedInputStream 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 (IOException e) { } return status; } /** * Reads GIF image from stream * * @param InputStream containing GIF file. * @return read status code (0 = no errors) */ public int read(InputStream is) { init(); if (is != null) { if (!(is instanceof BufferedInputStream)) is = new BufferedInputStream(is); in = (BufferedInputStream) is; readHeader(); if (!err()) { readContents(); if (frameCount < 0) { status = STATUS_FORMAT_ERROR; } } } else { status = STATUS_OPEN_ERROR; } try { is.close(); } catch (IOException e) { } return status; } /** * Reads G