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static/plugins/spice-html5/lz.js 5.44 KB
831eac332   zhuzhenchao   add file
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  "use strict";
  /*
     Copyright (C) 2012 by Jeremy P. White <jwhite@codeweavers.com>
  
     This file is part of spice-html5.
  
     spice-html5 is free software: you can redistribute it and/or modify
     it under the terms of the GNU Lesser General Public License as published by
     the Free Software Foundation, either version 3 of the License, or
     (at your option) any later version.
  
     spice-html5 is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU Lesser General Public License for more details.
  
     You should have received a copy of the GNU Lesser General Public License
     along with spice-html5.  If not, see <http://www.gnu.org/licenses/>.
  */
  
  
  /*----------------------------------------------------------------------------
  **  lz.js
  **      Functions for handling SPICE_IMAGE_TYPE_LZ_RGB
  **  Adapted from lz.c .
  **--------------------------------------------------------------------------*/
  function lz_rgb32_decompress(in_buf, at, out_buf, type, default_alpha)
  {
      var encoder = at;
      var op = 0;
      var ctrl;
      var ctr = 0;
  
      for (ctrl = in_buf[encoder++]; (op * 4) < out_buf.length; ctrl = in_buf[encoder++])
      {
          var ref = op;
          var len = ctrl >> 5;
          var ofs = (ctrl & 31) << 8;
  
  //if (type == LZ_IMAGE_TYPE_RGBA)
  //console.log(ctr++ + ": from " + (encoder + 28) + ", ctrl " + ctrl + ", len " + len + ", ofs " + ofs + ", op " + op);
          if (ctrl >= 32) {
  
              var code;
              len--;
  
              if (len == 7 - 1) {
                  do {
                      code = in_buf[encoder++];
                      len += code;
                  } while (code == 255);
              }
              code = in_buf[encoder++];
              ofs += code;
  
  
              if (code == 255) {
                  if ((ofs - code) == (31 << 8)) {
                      ofs = in_buf[encoder++] << 8;
                      ofs += in_buf[encoder++];
                      ofs += 8191;
                  }
              }
              len += 1;
              if (type == LZ_IMAGE_TYPE_RGBA)
                  len += 2;
  
              ofs += 1;
  
              ref -= ofs;
              if (ref == (op - 1)) {
                  var b = ref;
  //if (type == LZ_IMAGE_TYPE_RGBA) console.log("alpha " + out_buf[(b*4)+3] + " dupped into pixel " + op + " through pixel " + (op + len));
                  for (; len; --len) {
                      if (type == LZ_IMAGE_TYPE_RGBA)
                      {
                          out_buf[(op*4) + 3] = out_buf[(b*4)+3];
                      }
                      else
                      {
                          for (i = 0; i < 4; i++)
                              out_buf[(op*4) + i] = out_buf[(b*4)+i];
                      }
                      op++;
                  }
              } else {
  //if (type == LZ_IMAGE_TYPE_RGBA) console.log("alpha copied to pixel " + op + " through " + (op + len) + " from " + ref);
                  for (; len; --len) {
                      if (type == LZ_IMAGE_TYPE_RGBA)
                      {
                          out_buf[(op*4) + 3] = out_buf[(ref*4)+3];
                      }
                      else
                      {
                          for (i = 0; i < 4; i++)
                              out_buf[(op*4) + i] = out_buf[(ref*4)+i];
                      }
                      op++; ref++;
                  }
              }
          } else {
              ctrl++;
  
              if (type == LZ_IMAGE_TYPE_RGBA)
              {
  //console.log("alpha " + in_buf[encoder] + " set into pixel " + op);
                  out_buf[(op*4) + 3] = in_buf[encoder++];
              }
              else
              {
                  out_buf[(op*4) + 0] = in_buf[encoder + 2];
                  out_buf[(op*4) + 1] = in_buf[encoder + 1];
                  out_buf[(op*4) + 2] = in_buf[encoder + 0];
                  if (default_alpha)
                      out_buf[(op*4) + 3] = 255;
                  encoder += 3;
              }
              op++;
  
  
              for (--ctrl; ctrl; ctrl--) {
                  if (type == LZ_IMAGE_TYPE_RGBA)
                  {
  //console.log("alpha " + in_buf[encoder] + " set into pixel " + op);
                      out_buf[(op*4) + 3] = in_buf[encoder++];
                  }
                  else
                  {
                      out_buf[(op*4) + 0] = in_buf[encoder + 2];
                      out_buf[(op*4) + 1] = in_buf[encoder + 1];
                      out_buf[(op*4) + 2] = in_buf[encoder + 0];
                      if (default_alpha)
                          out_buf[(op*4) + 3] = 255;
                      encoder += 3;
                  }
                  op++;
              }
          }
  
      }
      return encoder - 1;
  }
  
  function convert_spice_lz_to_web(context, lz_image)
  {
      var at;
      if (lz_image.type === LZ_IMAGE_TYPE_RGB32 || lz_image.type === LZ_IMAGE_TYPE_RGBA)
      {
          var u8 = new Uint8Array(lz_image.data);
          var ret = context.createImageData(lz_image.width, lz_image.height);
  
          at = lz_rgb32_decompress(u8, 0, ret.data, LZ_IMAGE_TYPE_RGB32, lz_image.type != LZ_IMAGE_TYPE_RGBA);
          if (lz_image.type == LZ_IMAGE_TYPE_RGBA)
              lz_rgb32_decompress(u8, at, ret.data, LZ_IMAGE_TYPE_RGBA, false);
      }
      else if (lz_image.type === LZ_IMAGE_TYPE_XXXA)
      {
          var u8 = new Uint8Array(lz_image.data);
          var ret = context.createImageData(lz_image.width, lz_image.height);
          lz_rgb32_decompress(u8, 0, ret.data, LZ_IMAGE_TYPE_RGBA, false);
      }
      else
          return undefined;
  
      return ret;
  }