rfb/tightDecode.h

/* Copyright (C) 2000-2003 Constantin Kaplinsky.  All Rights Reserved.
 * Copyright (C) 2004 Peter Astrand, Cendio AB.  All Rights Reserved.
 *    
 * This is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * This software 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this software; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
 * USA.
 */

//
// Tight decoding functions.
//
// This file is #included after having set the following macros:
// BPP                - 8, 16 or 32
// EXTRA_ARGS         - optional extra arguments
// FILL_RECT          - fill a rectangle with a single colour
// IMAGE_RECT         - draw a rectangle of pixel data from a buffer

#include <rdr/InStream.h>
#include <rdr/ZlibInStream.h>
#include <rfb/Exception.h>
#include <assert.h>

namespace rfb {

// CONCAT2E concatenates its arguments, expanding them if they are macros

#ifndef CONCAT2E
#define CONCAT2(a,b) a##b
#define CONCAT2E(a,b) CONCAT2(a,b)
#endif

#define PIXEL_T rdr::CONCAT2E(U,BPP)
#define READ_PIXEL CONCAT2E(readOpaque,BPP)
#define TIGHT_DECODE CONCAT2E(tightDecode,BPP)

#define TIGHT_MIN_TO_COMPRESS 12
static bool DecompressJpegRect(const Rect& r, rdr::InStream* is,
			       PIXEL_T* buf, CMsgHandler* handler);
static void FilterGradient(const Rect& r, rdr::InStream* is, int dataSize,
			   PIXEL_T* buf, CMsgHandler* handler);

// Main function implementing Tight decoder

void TIGHT_DECODE (const Rect& r, rdr::InStream* is,
                   rdr::ZlibInStream zis[], PIXEL_T* buf
#ifdef EXTRA_ARGS
                      , EXTRA_ARGS
#endif
                      )
{
  rdr::U8 comp_ctl = is->readU8();

  // Flush zlib streams if we are told by the server to do so.
  for (int i = 0; i < 4; i++) {
    if (comp_ctl & 1) {
      zis[i].reset();
    }
    comp_ctl >>= 1;
  }

  // "Fill" compression type.
  if (comp_ctl == rfbTightFill) {
    PIXEL_T pix = is->READ_PIXEL();
    FILL_RECT(r, pix);
    return;
  }

  // "JPEG" compression type.
  if (comp_ctl == rfbTightJpeg) {
    DecompressJpegRect(r, is, buf, handler);
    return;
  }

  // Quit on unsupported compression type.
  if (comp_ctl > rfbTightMaxSubencoding) {
    throw Exception("TightDecoder: bad subencoding value received");
    return;
  }

  // "Basic" compression type.
  int palSize = 0;
  static PIXEL_T palette[256];
  bool useGradient = false;

  if ((comp_ctl & rfbTightExplicitFilter) != 0) {
    rdr::U8 filterId = is->readU8();

    switch (filterId) {
    case rfbTightFilterPalette: 
      palSize = is->readU8() + 1;
      {
        for (int i = 0; i < palSize; i++)
          palette[i] = is->READ_PIXEL();
      }
      break;
    case rfbTightFilterGradient: 
      useGradient = true;
      break;
    case rfbTightFilterCopy:
      break;
    default:
      throw Exception("TightDecoder: unknown filter code received");
      return;
    }
  }

  int bppp = BPP;
  if (palSize != 0) {
    bppp = (palSize <= 2) ? 1 : 8;
  }

  // Determine if the data should be decompressed or just copied.
  int rowSize = (r.width() * bppp + 7) / 8;
  int dataSize = r.height() * rowSize;
  rdr::InStream *input;
  if (dataSize < TIGHT_MIN_TO_COMPRESS) {
    input = is;
  } else {
    int length = is->readCompactLength();
    int streamId = comp_ctl & 0x03;
    zis[streamId].setUnderlying(is, length);
    input = &zis[streamId];
  }

  if (palSize == 0) {
    // Truecolor data
    if (useGradient) {
	FilterGradient(r, input, dataSize, buf, handler);
    } else {
	input->readBytes(buf, dataSize);
    }
  } else {
    int x, y, b, w;
    PIXEL_T *ptr = buf;
    rdr::U8 bits;
    if (palSize <= 2) {
      // 2-color palette
      w = (r.width() + 7) / 8;
      for (y = 0; y < r.height(); y++) {
        for (x = 0; x < r.width() / 8; x++) {
          bits = input->readU8();
          for (b = 7; b >= 0; b--)
            *ptr++ = palette[bits >> b & 1];
        }
        if (r.width() % 8 != 0) {
          bits = input->readU8();
          for (b = 7; b >= 8 - r.width() % 8; b--) {
            *ptr++ = palette[bits >> b & 1];
          }
        }
      }
    } else {
      // 256-color palette
      for (y = 0; y < r.height(); y++)
        for (x = 0; x < r.width(); x++)
          *ptr++ = palette[input->readU8()];
    }
  }

  IMAGE_RECT(r, buf);
}

static bool
DecompressJpegRect(const Rect& r, rdr::InStream* is,
		   PIXEL_T* buf, CMsgHandler* handler)
{
  struct jpeg_decompress_struct cinfo;
  struct jpeg_error_mgr jerr;
  PIXEL_T *pixelPtr;
  JSAMPROW scanline;

  // Read length
  int compressedLen = is->readCompactLength();
  if (compressedLen <= 0) {
      throw Exception("Incorrect data received from the server.\n");
  }

  // Allocate netbuf and read in data
  rdr::U8* netbuf = new rdr::U8[compressedLen];
  if (!netbuf)
    throw Exception("rfb::tightDecode unable to allocate buffer");
  is->readBytes(netbuf, compressedLen);

  // Set up JPEG decompression
  cinfo.err = jpeg_std_error(&jerr);
  jpeg_create_decompress(&cinfo);
  JpegSetSrcManager(&cinfo, (char*)netbuf, compressedLen);
  jpeg_read_header(&cinfo, TRUE);
  cinfo.out_color_space = JCS_RGB;

  jpeg_start_decompress(&cinfo);
  if (cinfo.output_width != (unsigned)r.width() || cinfo.output_height != (unsigned)r.height() ||
      cinfo.output_components != 3) {
      jpeg_destroy_decompress(&cinfo);
      throw Exception("Tight Encoding: Wrong JPEG data received.\n");
  }

  // Decompress
  scanline = (JSAMPROW)buf;
  const rfb::PixelFormat& myFormat = handler->cp.pf();
  int bytesPerRow = cinfo.output_width * myFormat.bpp/8;
  while (cinfo.output_scanline < cinfo.output_height) {
    jpeg_read_scanlines(&cinfo, &scanline, 1);
    if (jpegError) {
      break;
    }

    pixelPtr = (PIXEL_T*)(scanline);
    for (int dx = 0; dx < r.width(); dx++) {
      *pixelPtr++ = 
	RGB24_TO_PIXEL(scanline[dx*3], scanline[dx*3+1], scanline[dx*3+2]);
    }
    scanline += bytesPerRow;
  }

  IMAGE_RECT(r, buf);

  if (!jpegError)
    jpeg_finish_decompress(&cinfo);

  jpeg_destroy_decompress(&cinfo);

  delete [] netbuf;

  return !jpegError;
}


static void
FilterGradient(const Rect& r, rdr::InStream* is, int dataSize,
	       PIXEL_T* buf, CMsgHandler* handler)
{
  int x, y, c;
  static PIXEL_T prevRow[TIGHT_MAX_WIDTH*sizeof(PIXEL_T)];
  static PIXEL_T thisRow[TIGHT_MAX_WIDTH*sizeof(PIXEL_T)];
  int pix[3]; 
  int max[3]; 
  int shift[3]; 
  int est[3]; 

  memset(prevRow, 0, sizeof(prevRow));

  // Allocate netbuf and read in data
  PIXEL_T *netbuf = (PIXEL_T*)new rdr::U8[dataSize];
  if (!netbuf)
    throw Exception("rfb::tightDecode unable to allocate buffer");
  is->readBytes(netbuf, dataSize);

  // Set up shortcut variables
  const rfb::PixelFormat& myFormat = handler->cp.pf();
  max[0] = myFormat.redMax; 
  max[1] = myFormat.greenMax; 
  max[2] = myFormat.blueMax; 
  shift[0] = myFormat.redShift; 
  shift[1] = myFormat.greenShift; 
  shift[2] = myFormat.blueShift; 
  int rectHeight = r.height();
  int rectWidth = r.width();

  for (y = 0; y < rectHeight; y++) {
    /* First pixel in a row */
    for (c = 0; c < 3; c++) {
      pix[c] = (netbuf[y*rectWidth] >> shift[c]) + prevRow[c] & max[c];
      thisRow[c] = pix[c];
    }
    buf[y*rectWidth] = RGB_TO_PIXEL(pix[0], pix[1], pix[2]);

    /* Remaining pixels of a row */
    for (x = 1; x < rectWidth; x++) {
      for (c = 0; c < 3; c++) {
	est[c] = prevRow[x*3+c] + pix[c] - prevRow[(x-1)*3+c];
	if (est[c] > max[c]) {
	  est[c] = max[c];
	} else if (est[c] < 0) {
	  est[c] = 0;
	}
	pix[c] = (netbuf[y*rectWidth+x] >> shift[c]) + est[c] & max[c];
	thisRow[x*3+c] = pix[c];
      }
      buf[y*rectWidth+x] = RGB_TO_PIXEL(pix[0], pix[1], pix[2]);
    }

    memcpy(prevRow, thisRow, sizeof(prevRow));
  }

  delete [] netbuf;
}

#undef TIGHT_MIN_TO_COMPRESS
#undef TIGHT_DECODE
#undef READ_PIXEL
#undef PIXEL_T
}