content: /*
   ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
   ~                                                                               ~
   ~ The MIT License (MIT)                                                         ~
   ~                                                                               ~
   ~ Copyright (c) 2015-2025 miaixz.org and other contributors.                    ~
   ~                                                                               ~
   ~ Permission is hereby granted, free of charge, to any person obtaining a copy  ~
   ~ of this software and associated documentation files (the "Software"), to deal ~
   ~ in the Software without restriction, including without limitation the rights  ~
   ~ to use, copy, modify, merge, publish, distribute, sublicense, and/or sell     ~
   ~ copies of the Software, and to permit persons to whom the Software is         ~
   ~ furnished to do so, subject to the following conditions:                      ~
   ~                                                                               ~
   ~ The above copyright notice and this permission notice shall be included in    ~
   ~ all copies or substantial portions of the Software.                           ~
   ~                                                                               ~
   ~ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR    ~
   ~ IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,      ~
   ~ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE   ~
   ~ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER        ~
   ~ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, ~
   ~ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN     ~
   ~ THE SOFTWARE.                                                                 ~
   ~                                                                               ~
   ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
  */
  package org.miaixz.bus.extra.image.gif;
  
  import java.io.IOException;
  import java.io.OutputStream;
  
  import org.miaixz.bus.core.lang.Normal;
  
  //==============================================================================
  //  Adapted from Jef Poskanzer's Java port by way of J. M. G. Elliott.
  //  K Weiner 12/00
  
  class LZWEncoder {
  
      static final int BITS = 12;
      static final int HSIZE = 5003; // 80% occupancy
      int n_bits; // number of bits/code
      int maxbits = BITS; // user settable max # bits/code
      int maxcode; // maximum code, given n_bits
  
      // GIFCOMPR.C - GIF Image compression routines
      //
      // Lempel-Ziv compression based on 'compress'. GIF modifications by
      // David Rowley (mgardi@watdcsu.waterloo.edu)
  
      // General DEFINEs
      int maxmaxcode = 1 << BITS; // should NEVER generate this code
      int[] htab = new int[HSIZE];
  
      // GIF Image compression - modified 'compress'
      //
      // Based on: compress.c - File compression ala IEEE Computer, June 1984.
      //
      // By Authors: Spencer W. Thomas (decvax!harpo!utah-cs!utah-gr!thomas)
      // Jim McKie (decvax!mcvax!jim)
      // Steve Davies (decvax!vax135!petsd!peora!srd)
      // Ken Turkowski (decvax!decwrl!turtlevax!ken)
      // James A. Woods (decvax!ihnp4!ames!jaw)
      // Joe Orost (decvax!vax135!petsd!joe)
      int[] codetab = new int[HSIZE];
      int hsize = HSIZE; // for dynamic table sizing
      int free_ent = 0; // first unused entry
      // block compression parameters -- after all codes are used up,
      // and compression rate changes, start over.
      boolean clear_flg = false;
      int g_init_bits;
      int ClearCode;
      int EOFCode;
      int cur_accum = 0;
      int cur_bits = 0;
  
      // Algorithm: use open addressing double hashing (no chaining) on the
      // prefix code / next character combination. We do a variant of Knuth's
      // algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime
      // secondary probe. Here, the modular division first probe is gives way
      // to a faster exclusive-or manipulation. Also do block compression with
      // an adaptive reset, whereby the code table is cleared when the compression
      // ratio decreases, but after the table fills. The variable-length output
      // codes are re-sized at this point, and a special CLEAR code is generated
      // for the decompressor. Late addition: construct the table according to
      // file size for noticeable speed improvement on small files. Please direct
      // questions about this implementation to ames!jaw.
      int masks[] = { 0x0000, 0x0001, 0x0003, 0x0007, 0x000F, 0x001F, 0x003F, 0x007F, 0x00FF, 0x01FF, 0x03FF, 0x07FF,
              0x0FFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF };
      // Number of characters so far in this 'packet'
      int a_count;
      // Define the storage for the packet accumulator
      byte[] accum = new byte[256];
  
      // output
      //
      // Output the given code.
      // Inputs:
      // code: A n_bits-bit integer. If == -1, then EOF. This assumes
      // that n_bits =< wordsize - 1.
      // Outputs:
      // Outputs code to the file.
      // Assumptions:
      // Chars are 8 bits long.
      // Algorithm:
      // Maintain a BITS character long buffer (so that 8 codes will
      // fit in it exactly). Use the VAX insv instruction to insert each
      // code in turn. When the buffer fills up empty it and start over.
      private int imgW, imgH;
      private byte[] pixAry;
      private int initCodeSize;
      private int remaining;
      private int curPixel;
  
      // ----------------------------------------------------------------------------
      LZWEncoder(int width, int height, byte[] pixels, int color_depth) {
          imgW = width;
          imgH = height;
          pixAry = pixels;
          initCodeSize = Math.max(2, color_depth);
      }
  
      // Add a character to the end of the current packet, and if it is 254
      // characters, flush the packet to disk.
      void char_out(byte c, OutputStream outs) throws IOException {
          accum[a_count++] = c;
          if (a_count >= 254)
              flush_char(outs);
      }
  
      // Clear out the hash table
  
      // table clear for block compress
      void cl_block(OutputStream outs) throws IOException {
          cl_hash(hsize);
          free_ent = ClearCode + 2;
          clear_flg = true;
  
          output(ClearCode, outs);
      }
  
      // reset code table
      void cl_hash(int hsize) {
          for (int i = 0; i < hsize; ++i)
              htab[i] = -1;
      }
  
      void compress(int init_bits, OutputStream outs) throws IOException {
          int fcode;
          int i /* = 0 */;
          int c;
          int ent;
          int disp;
          int hsize_reg;
          int hshift;
  
          // Set up the globals: g_init_bits - initial number of bits
          g_init_bits = init_bits;
  
          // Set up the necessary values
          clear_flg = false;
          n_bits = g_init_bits;
          maxcode = MAXCODE(n_bits);
  
          ClearCode = 1 << (init_bits - 1);
          EOFCode = ClearCode + 1;
          free_ent = ClearCode + 2;
  
          a_count = 0; // clear packet
  
          ent = nextPixel();
  
          hshift = 0;
          for (fcode = hsize; fcode < 65536; fcode *= 2)
              ++hshift;
          hshift = 8 - hshift; // set hash code range bound
  
          hsize_reg = hsize;
          cl_hash(hsize_reg); // clear hash table
  
          output(ClearCode, outs);
  
          outer_loop: while ((c = nextPixel()) != Normal.__1) {
              fcode = (c << maxbits) + ent;
              i = (c << hshift) ^ ent; // xor hashing
  
              if (htab[i] == fcode) {
                  ent = codetab[i];
                  continue;
              } else if (htab[i] >= 0) // non-empty slot
              {
                  disp = hsize_reg - i; // secondary hash (after G. Knott)
                  if (i == 0)
                      disp = 1;
                  do {
                      if ((i -= disp) < 0)
                          i += hsize_reg;
  
                      if (htab[i] == fcode) {
                          ent = codetab[i];
                          continue outer_loop;
                      }
                  } while (htab[i] >= 0);
              }
              output(ent, outs);
              ent = c;
              if (free_ent < maxmaxcode) {
                  codetab[i] = free_ent++; // code -> hashtable
                  htab[i] = fcode;
              } else
                  cl_block(outs);
          }
          // Put out the final code.
          output(ent, outs);
          output(EOFCode, outs);
      }
  
      // ----------------------------------------------------------------------------
      void encode(OutputStream os) throws IOException {
          os.write(initCodeSize); // write "initial code size" byte
  
          remaining = imgW * imgH; // reset navigation variables
          curPixel = 0;
  
          compress(initCodeSize + 1, os); // compress and write the pixel data
  
          os.write(0); // write block terminator
      }
  
      // Flush the packet to disk, and reset the accumulator
      void flush_char(OutputStream outs) throws IOException {
          if (a_count > 0) {
              outs.write(a_count);
              outs.write(accum, 0, a_count);
              a_count = 0;
          }
      }
  
      final int MAXCODE(int n_bits) {
          return (1 << n_bits) - 1;
      }
  
      // ----------------------------------------------------------------------------
      // Return the next pixel from the image
      // ----------------------------------------------------------------------------
      private int nextPixel() {
          if (remaining == 0)
              return Normal.__1;
  
          --remaining;
  
          byte pix = pixAry[curPixel++];
  
          return pix & 0xff;
      }
  
      void output(int code, OutputStream outs) throws IOException {
          cur_accum &= masks[cur_bits];
  
          if (cur_bits > 0)
              cur_accum |= (code << cur_bits);
          else
              cur_accum = code;
  
          cur_bits += n_bits;
  
          while (cur_bits >= 8) {
              char_out((byte) (cur_accum & 0xff), outs);
              cur_accum >>= 8;
              cur_bits -= 8;
          }
  
          // If the next entry is going to be too big for the code size,
          // then increase it, if possible.
          if (free_ent > maxcode || clear_flg) {
              if (clear_flg) {
                  maxcode = MAXCODE(n_bits = g_init_bits);
                  clear_flg = false;
              } else {
                  ++n_bits;
                  if (n_bits == maxbits)
                      maxcode = maxmaxcode;
                  else
                      maxcode = MAXCODE(n_bits);
              }
          }
  
          if (code == EOFCode) {
              // At EOF, write the rest of the buffer.
              while (cur_bits > 0) {
                  char_out((byte) (cur_accum & 0xff), outs);
                  cur_accum >>= 8;
                  cur_bits -= 8;
              }
  
              flush_char(outs);
          }
      }
  
  }
  