corre.c

unix vnc 协议源码. VNC是一款远程控制工具软件.

/*
 * corre.c
 *
 * Routines to implement Compact Rise-and-Run-length Encoding (CoRRE).  This
 * code is based on krw's original javatel rfbserver.
 */

/*
 *  Copyright (C) 1999 AT&T Laboratories Cambridge.  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.
 */

#include <stdio.h>
#include "rfb.h"

/*
 * rreBeforeBuf contains pixel data in the client's format.
 * rreAfterBuf contains the RRE encoded version.  If the RRE encoded version is
 * larger than the raw data or if it exceeds rreAfterBufSize then
 * raw encoding is used instead.
 */

static int rreBeforeBufSize = 0;
static char *rreBeforeBuf = NULL;

static int rreAfterBufSize = 0;
static char *rreAfterBuf = NULL;
static int rreAfterBufLen;

static int subrectEncode8(CARD8 *data, int w, int h);
static int subrectEncode16(CARD16 *data, int w, int h);
static int subrectEncode32(CARD32 *data, int w, int h);
static CARD32 getBgColour(char *data, int size, int bpp);
static Bool rfbSendSmallRectEncodingCoRRE(rfbClientPtr cl, int x, int y,
					  int w, int h);


/*
 * rfbSendRectEncodingCoRRE - send an arbitrary size rectangle using CoRRE
 * encoding.
 */

Bool
rfbSendRectEncodingCoRRE(cl, x, y, w, h)
    rfbClientPtr cl;
    int x, y, w, h;
{
    if (h > cl->correMaxHeight) {
	return (rfbSendRectEncodingCoRRE(cl, x, y, w, cl->correMaxHeight) &&
		rfbSendRectEncodingCoRRE(cl, x, y + cl->correMaxHeight,
					 w, h - cl->correMaxHeight));
    }

    if (w > cl->correMaxWidth) {
	return (rfbSendRectEncodingCoRRE(cl, x, y, cl->correMaxWidth, h) &&
		rfbSendRectEncodingCoRRE(cl, x + cl->correMaxWidth, y,
					 w - cl->correMaxWidth, h));
    }

    return rfbSendSmallRectEncodingCoRRE(cl, x, y, w, h);
}



/*
 * rfbSendSmallRectEncodingCoRRE - send a small (guaranteed < 256x256)
 * rectangle using CoRRE encoding.
 */

static Bool
rfbSendSmallRectEncodingCoRRE(cl, x, y, w, h)
    rfbClientPtr cl;
    int x, y, w, h;
{
    rfbFramebufferUpdateRectHeader rect;
    rfbRREHeader hdr;
    int nSubrects;
    int i;
    char *fbptr = (rfbScreen.pfbMemory + (rfbScreen.paddedWidthInBytes * y)
		   + (x * (rfbScreen.bitsPerPixel / 8)));

    int maxRawSize = (rfbScreen.width * rfbScreen.height
		      * (cl->format.bitsPerPixel / 8));

    if (rreBeforeBufSize < maxRawSize) {
	rreBeforeBufSize = maxRawSize;
	if (rreBeforeBuf == NULL)
	    rreBeforeBuf = (char *)xalloc(rreBeforeBufSize);
	else
	    rreBeforeBuf = (char *)xrealloc(rreBeforeBuf, rreBeforeBufSize);
    }

    if (rreAfterBufSize < maxRawSize) {
	rreAfterBufSize = maxRawSize;
	if (rreAfterBuf == NULL)
	    rreAfterBuf = (char *)xalloc(rreAfterBufSize);
	else
	    rreAfterBuf = (char *)xrealloc(rreAfterBuf, rreAfterBufSize);
    }

    (*cl->translateFn)(cl->translateLookupTable, &rfbServerFormat,
		       &cl->format, fbptr, rreBeforeBuf,
		       rfbScreen.paddedWidthInBytes, w, h);

    switch (cl->format.bitsPerPixel) {
    case 8:
	nSubrects = subrectEncode8((CARD8 *)rreBeforeBuf, w, h);
	break;
    case 16:
	nSubrects = subrectEncode16((CARD16 *)rreBeforeBuf, w, h);
	break;
    case 32:
	nSubrects = subrectEncode32((CARD32 *)rreBeforeBuf, w, h);
	break;
    default:
	rfbLog("getBgColour: bpp %d?\n",cl->format.bitsPerPixel);
	exit(1);
    }
	
    if (nSubrects < 0) {

	/* RRE encoding was too large, use raw */

	return rfbSendRectEncodingRaw(cl, x, y, w, h);
    }

    cl->rfbRectanglesSent[rfbEncodingCoRRE]++;
    cl->rfbBytesSent[rfbEncodingCoRRE] += (sz_rfbFramebufferUpdateRectHeader
					   + sz_rfbRREHeader + rreAfterBufLen);

    if (ublen + sz_rfbFramebufferUpdateRectHeader + sz_rfbRREHeader
	> UPDATE_BUF_SIZE)
    {
	if (!rfbSendUpdateBuf(cl))
	    return FALSE;
    }

    rect.r.x = Swap16IfLE(x);
    rect.r.y = Swap16IfLE(y);
    rect.r.w = Swap16IfLE(w);
    rect.r.h = Swap16IfLE(h);
    rect.encoding = Swap32IfLE(rfbEncodingCoRRE);

    memcpy(&updateBuf[ublen], (char *)&rect,
	   sz_rfbFramebufferUpdateRectHeader);
    ublen += sz_rfbFramebufferUpdateRectHeader;

    hdr.nSubrects = Swap32IfLE(nSubrects);

    memcpy(&updateBuf[ublen], (char *)&hdr, sz_rfbRREHeader);
    ublen += sz_rfbRREHeader;

    for (i = 0; i < rreAfterBufLen;) {

	int bytesToCopy = UPDATE_BUF_SIZE - ublen;

	if (i + bytesToCopy > rreAfterBufLen) {
	    bytesToCopy = rreAfterBufLen - i;
	}

	memcpy(&updateBuf[ublen], &rreAfterBuf[i], bytesToCopy);

	ublen += bytesToCopy;
	i += bytesToCopy;

	if (ublen == UPDATE_BUF_SIZE) {
	    if (!rfbSendUpdateBuf(cl))
		return FALSE;
	}
    }

    return TRUE;
}



/*
 * subrectEncode() encodes the given multicoloured rectangle as a background 
 * colour overwritten by single-coloured rectangles.  It returns the number 
 * of subrectangles in the encoded buffer, or -1 if subrect encoding won't
 * fit in the buffer.  It puts the encoded rectangles in rreAfterBuf.  The
 * single-colour rectangle partition is not optimal, but does find the biggest
 * horizontal or vertical rectangle top-left anchored to each consecutive 
 * coordinate position.
 *
 * The coding scheme is simply [<bgcolour><subrect><subrect>...] where each 
 * <subrect> is [<colour><x><y><w><h>].
 */

#define DEFINE_SUBRECT_ENCODE(bpp)					      \
static int								      \
subrectEncode##bpp(data,w,h)						      \
    CARD##bpp *data;							      \
    int w;								      \
    int h;								      \
{									      \
    CARD##bpp cl;							      \
    rfbCoRRERectangle subrect;						      \
    int x,y;								      \
    int i,j;								      \
    int hx=0,hy,vx=0,vy;						      \
    int hyflag;								      \
    CARD##bpp *seg;							      \
    CARD##bpp *line;							      \
    int hw,hh,vw,vh;							      \
    int thex,they,thew,theh;						      \
    int numsubs = 0;							      \
    int newLen;								      \
    CARD##bpp bg = (CARD##bpp)getBgColour((char*)data,w*h,bpp);		      \
									      \
    *((CARD##bpp*)rreAfterBuf) = bg;					      \
									      \
    rreAfterBufLen = (bpp/8);						      \
									      \
    for (y=0; y<h; y++) {						      \
      line = data+(y*w);						      \
      for (x=0; x<w; x++) {						      \
        if (line[x] != bg) {						      \
          cl = line[x];							      \
          hy = y-1;							      \
          hyflag = 1;							      \
          for (j=y; j<h; j++) {						      \
            seg = data+(j*w);						      \
            if (seg[x] != cl) {break;}					      \
            i = x;							      \
            while ((seg[i] == cl) && (i < w)) i += 1;			      \
            i -= 1;							      \
            if (j == y) vx = hx = i;					      \
            if (i < vx) vx = i;						      \
            if ((hyflag > 0) && (i >= hx)) {hy += 1;} else {hyflag = 0;}      \
          }								      \
          vy = j-1;							      \
									      \
          /*  We now have two possible subrects: (x,y,hx,hy) and (x,y,vx,vy)  \
           *  We'll choose the bigger of the two.			      \
           */								      \
          hw = hx-x+1;							      \
          hh = hy-y+1;							      \
          vw = vx-x+1;							      \
          vh = vy-y+1;							      \
									      \
          thex = x;							      \
          they = y;							      \
									      \
          if ((hw*hh) > (vw*vh)) {					      \
            thew = hw;							      \
            theh = hh;							      \
          } else {							      \
            thew = vw;							      \
            theh = vh;							      \
          }								      \
									      \
          subrect.x = thex;						      \
          subrect.y = they;						      \
          subrect.w = thew;						      \
          subrect.h = theh;						      \
									      \
	  newLen = rreAfterBufLen + (bpp/8) + sz_rfbCoRRERectangle;	      \
          if ((newLen > (w * h * (bpp/8))) || (newLen > rreAfterBufSize))     \
	    return -1;							      \
									      \
	  numsubs += 1;							      \
	  *((CARD##bpp*)(rreAfterBuf + rreAfterBufLen)) = cl;		      \
	  rreAfterBufLen += (bpp/8);					      \
	  memcpy(&rreAfterBuf[rreAfterBufLen],&subrect,sz_rfbCoRRERectangle); \
	  rreAfterBufLen += sz_rfbCoRRERectangle;			      \
									      \
          /*								      \
           * Now mark the subrect as done.				      \
           */								      \
          for (j=they; j < (they+theh); j++) {				      \
            for (i=thex; i < (thex+thew); i++) {			      \
              data[j*w+i] = bg;						      \
            }								      \
          }								      \
        }								      \
      }									      \
    }									      \
									      \
    return numsubs;							      \
}

DEFINE_SUBRECT_ENCODE(8)
DEFINE_SUBRECT_ENCODE(16)
DEFINE_SUBRECT_ENCODE(32)


/*
 * getBgColour() gets the most prevalent colour in a byte array.
 */
static CARD32
getBgColour(data,size,bpp)
    char *data;
    int size;
    int bpp;
{
    
#define NUMCLRS 256
  
  static int counts[NUMCLRS];
  int i,j,k;

  int maxcount = 0;
  CARD8 maxclr = 0;

  if (bpp != 8) {
    if (bpp == 16) {
      return ((CARD16 *)data)[0];
    } else if (bpp == 32) {
      return ((CARD32 *)data)[0];
    } else {
      rfbLog("getBgColour: bpp %d?\n",bpp);
      exit(1);
    }
  }

  for (i=0; i<NUMCLRS; i++) {
    counts[i] = 0;
  }

  for (j=0; j<size; j++) {
    k = (int)(((CARD8 *)data)[j]);
    if (k >= NUMCLRS) {
      rfbLog("getBgColour: unusual colour = %d\n", k);
      exit(1);
    }
    counts[k] += 1;
    if (counts[k] > maxcount) {
      maxcount = counts[k];
      maxclr = ((CARD8 *)data)[j];
    }
  }
  
  return maxclr;
}