PC Online 1998 January/PCO0198.ISO/1&1/java.z/java_301/sun/awt/image/GifImageDecoder.class

Java Class File | 1996-10-20 | 5.3 KB | 207 lines

package sun.awt.image;

import java.awt.image.ImageConsumer;
import java.awt.image.IndexColorModel;
import java.io.IOException;
import java.io.InputStream;
import java.util.Hashtable;

public class GifImageDecoder extends ImageDecoder {
   private final boolean verbose = false;
   private static final int IMAGESEP = 44;
   private static final int EXBLOCK = 33;
   private static final int EX_GRAPHICS_CONTROL = 249;
   private static final int EX_COMMENT = 254;
   private static final int EX_APPLICATION = 255;
   private static final int TERMINATOR = 59;
   private static final int INTERLACEMASK = 64;
   private static final int COLORMAPMASK = 128;
   PixelStore8 store;
   int num_colors;
   byte[] colormap;
   IndexColorModel model;
   Hashtable props = new Hashtable();
   private static final int normalflags = 30;
   private static final int interlaceflags = 29;

   public GifImageDecoder(InputStreamImageSource src, InputStream is) {
      super(src, is);
   }

   public synchronized boolean catchupConsumer(InputStreamImageSource src, ImageConsumer ic) {
      return this.store == null || this.store.replay(src, ic);
   }

   public synchronized void makeStore(int width, int height) {
      this.store = new PixelStore8(width, height);
   }

   private static void error(String s1) throws ImageFormatException {
      throw new ImageFormatException(s1);
   }

   boolean readBytes(byte[] buf, int off, int len) {
      while(len > 0) {
         int n;
         try {
            n = super.input.read(buf, off, len);
         } catch (IOException var5) {
            n = -1;
         }

         if (n < 0) {
            return false;
         }

         off += n;
         len -= n;
      }

      return true;
   }

   public void produceImage() throws IOException, ImageFormatException {
      int trans_pixel = -1;

      try {
         this.readHeader();

         label248:
         while(true) {
            switch (super.input.read()) {
               case 59:
                  return;
               case 44:
                  try {
                     this.model = new IndexColorModel(8, this.num_colors, this.colormap, 0, false, trans_pixel);
                     this.colormap = null;
                     if (this.readImage()) {
                        this.store.imageComplete();
                        if (this.store.getBitState() != 2) {
                           super.source.setPixelStore(this.store);
                        }

                        super.source.imageComplete(3);
                        return;
                     }
                  } catch (ArrayIndexOutOfBoundsException var19) {
                  }

                  return;
               case -1:
                  return;
               case 33:
                  int code;
                  switch (code = super.input.read()) {
                     case 255:
                     case 254:
                     default:
                        String comment = "";

                        while(true) {
                           int n = super.input.read();
                           if (n == 0) {
                              if (code == 254) {
                                 this.props.put("comment", comment);
                              }
                              continue label248;
                           }

                           byte[] buf = new byte[n];
                           if (!this.readBytes(buf, 0, n)) {
                              return;
                           }

                           if (code == 254) {
                              comment = comment + new String(buf, 0);
                           }
                        }
                     case 249:
                        byte[] buf = new byte[6];
                        if (!this.readBytes(buf, 0, 6)) {
                           return;
                        }

                        if (buf[0] != 4 || buf[5] != 0) {
                           return;
                        }

                        trans_pixel = buf[4] & 255;
                        continue;
                  }
               default:
                  return;
            }
         }
      } finally {
         try {
            super.input.close();
         } catch (IOException var18) {
         }

      }
   }

   private void readHeader() throws IOException, ImageFormatException {
      byte[] buf = new byte[13];
      if (!this.readBytes(buf, 0, 13)) {
         throw new IOException();
      } else {
         if (buf[0] != 71 || buf[1] != 73 || buf[2] != 70) {
            error("not a GIF file.");
         }

         int ch = buf[10] & 255;
         if ((ch & 128) == 0) {
            error("no global colormap in GIF file.");
         }

         this.num_colors = 1 << (ch & 7) + 1;
         if (buf[12] != 0) {
            error("corrupt GIF file (no null).");
         }

         this.colormap = new byte[this.num_colors * 3];
         if (!this.readBytes(this.colormap, 0, this.num_colors * 3)) {
            throw new IOException();
         }
      }
   }

   private native boolean parseImage(int var1, int var2, boolean var3, int var4, byte[] var5, byte[] var6);

   private int sendPixels(int y, int width, byte[] rasline) {
      int count = super.source.setPixels(0, y, width, 1, this.model, rasline, 0, width);
      if (this.store.setPixels(0, y, width, 1, rasline, 0, width)) {
         ++count;
      }

      return count;
   }

   private boolean readImage() throws IOException {
      long tm = 0L;
      byte[] block = new byte[259];
      if (!this.readBytes(block, 0, 10)) {
         throw new IOException();
      } else {
         int width = block[4] & 255 | block[5] << 8;
         int height = block[6] & 255 | block[7] << 8;
         boolean interlace = (block[8] & 64) != 0;
         int initCodeSize = block[9] & 255;
         super.source.setDimensions(width, height);
         this.makeStore(width, height);
         super.source.setProperties(this.props);
         this.store.setProperties(this.props);
         super.source.setColorModel(this.model);
         this.store.setColorModel(this.model);
         int hints = interlace ? 29 : 30;
         super.source.setHints(hints);
         this.store.setHints(hints);
         byte[] rasline = new byte[width];
         boolean ret = this.parseImage(width, height, interlace, initCodeSize, block, rasline);
         return ret;
      }
   }
}