libtdevnc/libvncserver/tight.c

/*
 * tight.c
 *
 * Routines to implement Tight Encoding
 */

/*
 *  Copyright (C) 2000, 2001 Const Kaplinsky.  All Rights Reserved.
 *  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/rfb.h>
#include "private.h"

#ifdef WIN32
#define XMD_H
#undef FAR
#define NEEDFAR_POINTERS
#endif

#ifdef _RPCNDR_H /* This Windows header typedefs 'boolean', jpeglib has to know */
#define HAVE_BOOLEAN
#endif
#ifdef LIBVNCSERVER_HAVE_LIBPNG
#include <png.h>
#endif
#include <jpeglib.h>

/* Note: The following constant should not be changed. */
#define TIGHT_MIN_TO_COMPRESS 12

/* The parameters below may be adjusted. */
#define MIN_SPLIT_RECT_SIZE     4096
#define MIN_SOLID_SUBRECT_SIZE  2048
#define MAX_SPLIT_TILE_SIZE       16

/* May be set to TRUE with "-lazytight" Xvnc option. */
rfbBool rfbTightDisableGradient = FALSE;

/*
 * There is so much access of the Tight encoding static data buffers
 * that we resort to using thread local storage instead of having
 * per-client data.
 */
#if LIBVNCSERVER_HAVE_LIBPTHREAD && LIBVNCSERVER_HAVE_TLS && !defined(TLS) && defined(__linux__)
#define TLS __thread
#endif
#ifndef TLS
#define TLS
#endif

/* This variable is set on every rfbSendRectEncodingTight() call. */
static TLS rfbBool usePixelFormat24 = FALSE;

/* Compression level stuff. The following array contains various
   encoder parameters for each of 10 compression levels (0..9).
   Last three parameters correspond to JPEG quality levels (0..9). */

typedef struct TIGHT_CONF_s {
    int maxRectSize, maxRectWidth;
    int monoMinRectSize, gradientMinRectSize;
    int idxZlibLevel, monoZlibLevel, rawZlibLevel, gradientZlibLevel;
    int gradientThreshold, gradientThreshold24;
    int idxMaxColorsDivisor;
    int jpegQuality, jpegThreshold, jpegThreshold24;
} TIGHT_CONF;

static TIGHT_CONF tightConf[10] = {
    {   512,   32,   6, 65536, 0, 0, 0, 0,   0,   0,   4,  5, 10000, 23000 },
    {  2048,  128,   6, 65536, 1, 1, 1, 0,   0,   0,   8, 10,  8000, 18000 },
    {  6144,  256,   8, 65536, 3, 3, 2, 0,   0,   0,  24, 15,  6500, 15000 },
    { 10240, 1024,  12, 65536, 5, 5, 3, 0,   0,   0,  32, 25,  5000, 12000 },
    { 16384, 2048,  12, 65536, 6, 6, 4, 0,   0,   0,  32, 37,  4000, 10000 },
    { 32768, 2048,  12,  4096, 7, 7, 5, 4, 150, 380,  32, 50,  3000,  8000 },
    { 65536, 2048,  16,  4096, 7, 7, 6, 4, 170, 420,  48, 60,  2000,  5000 },
    { 65536, 2048,  16,  4096, 8, 8, 7, 5, 180, 450,  64, 70,  1000,  2500 },
    { 65536, 2048,  32,  8192, 9, 9, 8, 6, 190, 475,  64, 75,   500,  1200 },
    { 65536, 2048,  32,  8192, 9, 9, 9, 6, 200, 500,  96, 80,   200,   500 }
};

#ifdef LIBVNCSERVER_HAVE_LIBPNG
typedef struct TIGHT_PNG_CONF_s {
    int png_zlib_level, png_filters;
} TIGHT_PNG_CONF;

static TIGHT_PNG_CONF tightPngConf[10] = {
    { 0, PNG_NO_FILTERS },
    { 1, PNG_NO_FILTERS },
    { 2, PNG_NO_FILTERS },
    { 3, PNG_NO_FILTERS },
    { 4, PNG_NO_FILTERS },
    { 5, PNG_ALL_FILTERS },
    { 6, PNG_ALL_FILTERS },
    { 7, PNG_ALL_FILTERS },
    { 8, PNG_ALL_FILTERS },
    { 9, PNG_ALL_FILTERS },
};
#endif

static TLS int compressLevel = 0;
static TLS int qualityLevel = 0;

/* Stuff dealing with palettes. */

typedef struct COLOR_LIST_s {
    struct COLOR_LIST_s *next;
    int idx;
    uint32_t rgb;
} COLOR_LIST;

typedef struct PALETTE_ENTRY_s {
    COLOR_LIST *listNode;
    int numPixels;
} PALETTE_ENTRY;

typedef struct PALETTE_s {
    PALETTE_ENTRY entry[256];
    COLOR_LIST *hash[256];
    COLOR_LIST list[256];
} PALETTE;

/* TODO: move into rfbScreen struct */
static TLS int paletteNumColors = 0;
static TLS int paletteMaxColors = 0;
static TLS uint32_t monoBackground = 0;
static TLS uint32_t monoForeground = 0;
static TLS PALETTE palette;

/* Pointers to dynamically-allocated buffers. */

static TLS int tightBeforeBufSize = 0;
static TLS char *tightBeforeBuf = NULL;

static TLS int tightAfterBufSize = 0;
static TLS char *tightAfterBuf = NULL;

static TLS int *prevRowBuf = NULL;

void rfbTightCleanup(rfbScreenInfoPtr screen)
{
  if(tightBeforeBufSize) {
    free(tightBeforeBuf);
    tightBeforeBufSize=0;
    tightBeforeBuf = NULL;
  }
  if(tightAfterBufSize) {
    free(tightAfterBuf);
    tightAfterBufSize=0;
    tightAfterBuf = NULL;
  }
}

/* Prototypes for static functions. */

static rfbBool SendRectEncodingTight(rfbClientPtr cl, int x, int y,
                                     int w, int h);
static void FindBestSolidArea (rfbClientPtr cl, int x, int y, int w, int h,
                               uint32_t colorValue, int *w_ptr, int *h_ptr);
static void ExtendSolidArea   (rfbClientPtr cl, int x, int y, int w, int h,
                               uint32_t colorValue,
                               int *x_ptr, int *y_ptr, int *w_ptr, int *h_ptr);
static rfbBool CheckSolidTile    (rfbClientPtr cl, int x, int y, int w, int h,
                               uint32_t *colorPtr, rfbBool needSameColor);
static rfbBool CheckSolidTile8   (rfbClientPtr cl, int x, int y, int w, int h,
                               uint32_t *colorPtr, rfbBool needSameColor);
static rfbBool CheckSolidTile16  (rfbClientPtr cl, int x, int y, int w, int h,
                               uint32_t *colorPtr, rfbBool needSameColor);
static rfbBool CheckSolidTile32  (rfbClientPtr cl, int x, int y, int w, int h,
                               uint32_t *colorPtr, rfbBool needSameColor);

static rfbBool SendRectSimple    (rfbClientPtr cl, int x, int y, int w, int h);
static rfbBool SendSubrect       (rfbClientPtr cl, int x, int y, int w, int h);
static rfbBool SendTightHeader   (rfbClientPtr cl, int x, int y, int w, int h);

static rfbBool SendSolidRect     (rfbClientPtr cl);
static rfbBool SendMonoRect      (rfbClientPtr cl, int x, int y, int w, int h);
static rfbBool SendIndexedRect   (rfbClientPtr cl, int x, int y, int w, int h);
static rfbBool SendFullColorRect (rfbClientPtr cl, int x, int y, int w, int h);
static rfbBool SendGradientRect  (rfbClientPtr cl, int x, int y, int w, int h);

static rfbBool CompressData(rfbClientPtr cl, int streamId, int dataLen,
                         int zlibLevel, int zlibStrategy);
static rfbBool SendCompressedData(rfbClientPtr cl, int compressedLen);

static void FillPalette8(int count);
static void FillPalette16(int count);
static void FillPalette32(int count);

static void PaletteReset(void);
static int PaletteInsert(uint32_t rgb, int numPixels, int bpp);

static void Pack24(rfbClientPtr cl, char *buf, rfbPixelFormat *fmt, int count);

static void EncodeIndexedRect16(uint8_t *buf, int count);
static void EncodeIndexedRect32(uint8_t *buf, int count);

static void EncodeMonoRect8(uint8_t *buf, int w, int h);
static void EncodeMonoRect16(uint8_t *buf, int w, int h);
static void EncodeMonoRect32(uint8_t *buf, int w, int h);

static void FilterGradient24(rfbClientPtr cl, char *buf, rfbPixelFormat *fmt, int w, int h);
static void FilterGradient16(rfbClientPtr cl, uint16_t *buf, rfbPixelFormat *fmt, int w, int h);
static void FilterGradient32(rfbClientPtr cl, uint32_t *buf, rfbPixelFormat *fmt, int w, int h);

static int DetectSmoothImage(rfbClientPtr cl, rfbPixelFormat *fmt, int w, int h);
static unsigned long DetectSmoothImage24(rfbClientPtr cl, rfbPixelFormat *fmt, int w, int h);
static unsigned long DetectSmoothImage16(rfbClientPtr cl, rfbPixelFormat *fmt, int w, int h);
static unsigned long DetectSmoothImage32(rfbClientPtr cl, rfbPixelFormat *fmt, int w, int h);

static rfbBool SendJpegRect(rfbClientPtr cl, int x, int y, int w, int h,
                         int quality);
static void PrepareRowForImg(rfbClientPtr cl, uint8_t *dst, int x, int y, int count);
static void PrepareRowForImg24(rfbClientPtr cl, uint8_t *dst, int x, int y, int count);
static void PrepareRowForImg16(rfbClientPtr cl, uint8_t *dst, int x, int y, int count);
static void PrepareRowForImg32(rfbClientPtr cl, uint8_t *dst, int x, int y, int count);

static void JpegInitDestination(j_compress_ptr cinfo);
static boolean JpegEmptyOutputBuffer(j_compress_ptr cinfo);
static void JpegTermDestination(j_compress_ptr cinfo);
static void JpegSetDstManager(j_compress_ptr cinfo);

#ifdef LIBVNCSERVER_HAVE_LIBPNG
static rfbBool SendPngRect(rfbClientPtr cl, int x, int y, int w, int h);
static rfbBool CanSendPngRect(rfbClientPtr cl, int w, int h);
#endif

/*
 * Tight encoding implementation.
 */

int
rfbNumCodedRectsTight(rfbClientPtr cl,
                      int x,
                      int y,
                      int w,
                      int h)
{
    int maxRectSize, maxRectWidth;
    int subrectMaxWidth, subrectMaxHeight;

    /* No matter how many rectangles we will send if LastRect markers
       are used to terminate rectangle stream. */
    if (cl->enableLastRectEncoding && w * h >= MIN_SPLIT_RECT_SIZE)
      return 0;

    maxRectSize = tightConf[cl->tightCompressLevel].maxRectSize;
    maxRectWidth = tightConf[cl->tightCompressLevel].maxRectWidth;

    if (w > maxRectWidth || w * h > maxRectSize) {
        subrectMaxWidth = (w > maxRectWidth) ? maxRectWidth : w;
        subrectMaxHeight = maxRectSize / subrectMaxWidth;
        return (((w - 1) / maxRectWidth + 1) *
                ((h - 1) / subrectMaxHeight + 1));
    } else {
        return 1;
    }
}

rfbBool
rfbSendRectEncodingTight(rfbClientPtr cl,
                         int x,
                         int y,
                         int w,
                         int h)
{
    cl->tightEncoding = rfbEncodingTight;
    return SendRectEncodingTight(cl, x, y, w, h);
}

rfbBool
rfbSendRectEncodingTightPng(rfbClientPtr cl,
                         int x,
                         int y,
                         int w,
                         int h)
{
    cl->tightEncoding = rfbEncodingTightPng;
    return SendRectEncodingTight(cl, x, y, w, h);
}


rfbBool
SendRectEncodingTight(rfbClientPtr cl,
                         int x,
                         int y,
                         int w,
                         int h)
{
    int nMaxRows;
    uint32_t colorValue;
    int dx, dy, dw, dh;
    int x_best, y_best, w_best, h_best;
    char *fbptr;

    rfbSendUpdateBuf(cl);

    compressLevel = cl->tightCompressLevel;
    qualityLevel = cl->tightQualityLevel;

    if ( cl->format.depth == 24 && cl->format.redMax == 0xFF &&
         cl->format.greenMax == 0xFF && cl->format.blueMax == 0xFF ) {
        usePixelFormat24 = TRUE;
    } else {
        usePixelFormat24 = FALSE;
    }

    if (!cl->enableLastRectEncoding || w * h < MIN_SPLIT_RECT_SIZE)
        return SendRectSimple(cl, x, y, w, h);

    /* Make sure we can write at least one pixel into tightBeforeBuf. */

    if (tightBeforeBufSize < 4) {
        tightBeforeBufSize = 4;
        if (tightBeforeBuf == NULL)
            tightBeforeBuf = (char *)malloc(tightBeforeBufSize);
        else
            tightBeforeBuf = (char *)realloc(tightBeforeBuf,
                                              tightBeforeBufSize);
    }

    /* Calculate maximum number of rows in one non-solid rectangle. */

    {
        int maxRectSize, maxRectWidth, nMaxWidth;

        maxRectSize = tightConf[compressLevel].maxRectSize;
        maxRectWidth = tightConf[compressLevel].maxRectWidth;
        nMaxWidth = (w > maxRectWidth) ? maxRectWidth : w;
        nMaxRows = maxRectSize / nMaxWidth;
    }

    /* Try to find large solid-color areas and send them separately. */

    for (dy = y; dy < y + h; dy += MAX_SPLIT_TILE_SIZE) {

        /* If a rectangle becomes too large, send its upper part now. */

        if (dy - y >= nMaxRows) {
            if (!SendRectSimple(cl, x, y, w, nMaxRows))
                return 0;
            y += nMaxRows;
            h -= nMaxRows;
        }

        dh = (dy + MAX_SPLIT_TILE_SIZE <= y + h) ?
            MAX_SPLIT_TILE_SIZE : (y + h - dy);

        for (dx = x; dx < x + w; dx += MAX_SPLIT_TILE_SIZE) {

            dw = (dx + MAX_SPLIT_TILE_SIZE <= x + w) ?
                MAX_SPLIT_TILE_SIZE : (x + w - dx);

            if (CheckSolidTile(cl, dx, dy, dw, dh, &colorValue, FALSE)) {

                /* Get dimensions of solid-color area. */

                FindBestSolidArea(cl, dx, dy, w - (dx - x), h - (dy - y),
				  colorValue, &w_best, &h_best);

                /* Make sure a solid rectangle is large enough
                   (or the whole rectangle is of the same color). */

                if ( w_best * h_best != w * h &&
                     w_best * h_best < MIN_SOLID_SUBRECT_SIZE )
                    continue;

                /* Try to extend solid rectangle to maximum size. */

                x_best = dx; y_best = dy;
                ExtendSolidArea(cl, x, y, w, h, colorValue,
                                &x_best, &y_best, &w_best, &h_best);

                /* Send rectangles at top and left to solid-color area. */

                if ( y_best != y &&
                     !SendRectSimple(cl, x, y, w, y_best-y) )
                    return FALSE;
                if ( x_best != x &&
                     !SendRectEncodingTight(cl, x, y_best,
                                               x_best-x, h_best) )
                    return FALSE;

                /* Send solid-color rectangle. */

                if (!SendTightHeader(cl, x_best, y_best, w_best, h_best))
                    return FALSE;

                fbptr = (cl->scaledScreen->frameBuffer +
                         (cl->scaledScreen->paddedWidthInBytes * y_best) +
                         (x_best * (cl->scaledScreen->bitsPerPixel / 8)));

                (*cl->translateFn)(cl->translateLookupTable, &cl->screen->serverFormat,
                                   &cl->format, fbptr, tightBeforeBuf,
                                   cl->scaledScreen->paddedWidthInBytes, 1, 1);

                if (!SendSolidRect(cl))
                    return FALSE;

                /* Send remaining rectangles (at right and bottom). */

                if ( x_best + w_best != x + w &&
                     !SendRectEncodingTight(cl, x_best+w_best, y_best,
                                               w-(x_best-x)-w_best, h_best) )
                    return FALSE;
                if ( y_best + h_best != y + h &&
                     !SendRectEncodingTight(cl, x, y_best+h_best,
                                               w, h-(y_best-y)-h_best) )
                    return FALSE;

                /* Return after all recursive calls are done. */

                return TRUE;
            }

        }

    }

    /* No suitable solid-color rectangles found. */

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

static void
FindBestSolidArea(rfbClientPtr cl,
                  int x,
                  int y,
                  int w,
                  int h,
                  uint32_t colorValue,
                  int *w_ptr,
                  int *h_ptr)
{
    int dx, dy, dw, dh;
    int w_prev;
    int w_best = 0, h_best = 0;

    w_prev = w;

    for (dy = y; dy < y + h; dy += MAX_SPLIT_TILE_SIZE) {

        dh = (dy + MAX_SPLIT_TILE_SIZE <= y + h) ?
            MAX_SPLIT_TILE_SIZE : (y + h - dy);
        dw = (w_prev > MAX_SPLIT_TILE_SIZE) ?
            MAX_SPLIT_TILE_SIZE : w_prev;

        if (!CheckSolidTile(cl, x, dy, dw, dh, &colorValue, TRUE))
            break;

        for (dx = x + dw; dx < x + w_prev;) {
            dw = (dx + MAX_SPLIT_TILE_SIZE <= x + w_prev) ?
                MAX_SPLIT_TILE_SIZE : (x + w_prev - dx);
            if (!CheckSolidTile(cl, dx, dy, dw, dh, &colorValue, TRUE))
                break;
	    dx += dw;
        }

        w_prev = dx - x;
        if (w_prev * (dy + dh - y) > w_best * h_best) {
            w_best = w_prev;
            h_best = dy + dh - y;
        }
    }

    *w_ptr = w_best;
    *h_ptr = h_best;
}

static void
ExtendSolidArea(rfbClientPtr cl,
                int x,
                int y,
                int w,
                int h,
                uint32_t colorValue,
                int *x_ptr,
                int *y_ptr,
                int *w_ptr,
                int *h_ptr)
{
    int cx, cy;

    /* Try to extend the area upwards. */
    for ( cy = *y_ptr - 1;
          cy >= y && CheckSolidTile(cl, *x_ptr, cy, *w_ptr, 1, &colorValue, TRUE);
          cy-- );
    *h_ptr += *y_ptr - (cy + 1);
    *y_ptr = cy + 1;

    /* ... downwards. */
    for ( cy = *y_ptr + *h_ptr;
          cy < y + h &&
              CheckSolidTile(cl, *x_ptr, cy, *w_ptr, 1, &colorValue, TRUE);
          cy++ );
    *h_ptr += cy - (*y_ptr + *h_ptr);

    /* ... to the left. */
    for ( cx = *x_ptr - 1;
          cx >= x && CheckSolidTile(cl, cx, *y_ptr, 1, *h_ptr, &colorValue, TRUE);
          cx-- );
    *w_ptr += *x_ptr - (cx + 1);
    *x_ptr = cx + 1;

    /* ... to the right. */
    for ( cx = *x_ptr + *w_ptr;
          cx < x + w &&
              CheckSolidTile(cl, cx, *y_ptr, 1, *h_ptr, &colorValue, TRUE);
          cx++ );
    *w_ptr += cx - (*x_ptr + *w_ptr);
}

/*
 * Check if a rectangle is all of the same color. If needSameColor is
 * set to non-zero, then also check that its color equals to the
 * *colorPtr value. The result is 1 if the test is successfull, and in
 * that case new color will be stored in *colorPtr.
 */

static rfbBool CheckSolidTile(rfbClientPtr cl, int x, int y, int w, int h, uint32_t* colorPtr, rfbBool needSameColor)
{
    switch(cl->screen->serverFormat.bitsPerPixel) {
    case 32:
        return CheckSolidTile32(cl, x, y, w, h, colorPtr, needSameColor);
    case 16:
        return CheckSolidTile16(cl, x, y, w, h, colorPtr, needSameColor);
    default:
        return CheckSolidTile8(cl, x, y, w, h, colorPtr, needSameColor);
    }
}

#define DEFINE_CHECK_SOLID_FUNCTION(bpp)                                      \
                                                                              \
static rfbBool                                                                \
CheckSolidTile##bpp(rfbClientPtr cl, int x, int y, int w, int h,              \
		uint32_t* colorPtr, rfbBool needSameColor)                    \
{                                                                             \
    uint##bpp##_t *fbptr;                                                     \
    uint##bpp##_t colorValue;                                                 \
    int dx, dy;                                                               \
                                                                              \
    fbptr = (uint##bpp##_t *)                                                 \
        &cl->scaledScreen->frameBuffer[y * cl->scaledScreen->paddedWidthInBytes + x * (bpp/8)]; \
                                                                              \
    colorValue = *fbptr;                                                      \
    if (needSameColor && (uint32_t)colorValue != *colorPtr)                   \
        return FALSE;                                                         \
                                                                              \
    for (dy = 0; dy < h; dy++) {                                              \
        for (dx = 0; dx < w; dx++) {                                          \
            if (colorValue != fbptr[dx])                                      \
                return FALSE;                                                 \
        }                                                                     \
        fbptr = (uint##bpp##_t *)((uint8_t *)fbptr + cl->scaledScreen->paddedWidthInBytes); \
    }                                                                         \
                                                                              \
    *colorPtr = (uint32_t)colorValue;                                         \
    return TRUE;                                                              \
}

DEFINE_CHECK_SOLID_FUNCTION(8)
DEFINE_CHECK_SOLID_FUNCTION(16)
DEFINE_CHECK_SOLID_FUNCTION(32)

static rfbBool
SendRectSimple(rfbClientPtr cl, int x, int y, int w, int h)
{
    int maxBeforeSize, maxAfterSize;
    int maxRectSize, maxRectWidth;
    int subrectMaxWidth, subrectMaxHeight;
    int dx, dy;
    int rw, rh;

    maxRectSize = tightConf[compressLevel].maxRectSize;
    maxRectWidth = tightConf[compressLevel].maxRectWidth;

    maxBeforeSize = maxRectSize * (cl->format.bitsPerPixel / 8);
    maxAfterSize = maxBeforeSize + (maxBeforeSize + 99) / 100 + 12;

    if (tightBeforeBufSize < maxBeforeSize) {
        tightBeforeBufSize = maxBeforeSize;
        if (tightBeforeBuf == NULL)
            tightBeforeBuf = (char *)malloc(tightBeforeBufSize);
        else
            tightBeforeBuf = (char *)realloc(tightBeforeBuf,
                                              tightBeforeBufSize);
    }

    if (tightAfterBufSize < maxAfterSize) {
        tightAfterBufSize = maxAfterSize;
        if (tightAfterBuf == NULL)
            tightAfterBuf = (char *)malloc(tightAfterBufSize);
        else
            tightAfterBuf = (char *)realloc(tightAfterBuf,
                                             tightAfterBufSize);
    }

    if (w > maxRectWidth || w * h > maxRectSize) {
        subrectMaxWidth = (w > maxRectWidth) ? maxRectWidth : w;
        subrectMaxHeight = maxRectSize / subrectMaxWidth;

        for (dy = 0; dy < h; dy += subrectMaxHeight) {
            for (dx = 0; dx < w; dx += maxRectWidth) {
                rw = (dx + maxRectWidth < w) ? maxRectWidth : w - dx;
                rh = (dy + subrectMaxHeight < h) ? subrectMaxHeight : h - dy;
                if (!SendSubrect(cl, x+dx, y+dy, rw, rh))
                    return FALSE;
            }
        }
    } else {
        if (!SendSubrect(cl, x, y, w, h))
            return FALSE;
    }

    return TRUE;
}

static rfbBool
SendSubrect(rfbClientPtr cl,
            int x,
            int y,
            int w,
            int h)
{
    char *fbptr;
    rfbBool success = FALSE;

    /* Send pending data if there is more than 128 bytes. */
    if (cl->ublen > 128) {
        if (!rfbSendUpdateBuf(cl))
            return FALSE;
    }

    if (!SendTightHeader(cl, x, y, w, h))
        return FALSE;

    fbptr = (cl->scaledScreen->frameBuffer + (cl->scaledScreen->paddedWidthInBytes * y)
             + (x * (cl->scaledScreen->bitsPerPixel / 8)));

    (*cl->translateFn)(cl->translateLookupTable, &cl->screen->serverFormat,
                       &cl->format, fbptr, tightBeforeBuf,
                       cl->scaledScreen->paddedWidthInBytes, w, h);

    paletteMaxColors = w * h / tightConf[compressLevel].idxMaxColorsDivisor;
    if ( paletteMaxColors < 2 &&
         w * h >= tightConf[compressLevel].monoMinRectSize ) {
        paletteMaxColors = 2;
    }
    switch (cl->format.bitsPerPixel) {
    case 8:
        FillPalette8(w * h);
        break;
    case 16:
        FillPalette16(w * h);
        break;
    default:
        FillPalette32(w * h);
    }

    switch (paletteNumColors) {
    case 0:
        /* Truecolor image */
        if (DetectSmoothImage(cl, &cl->format, w, h)) {
            if (qualityLevel != -1) {
                success = SendJpegRect(cl, x, y, w, h,
                                       tightConf[qualityLevel].jpegQuality);
            } else {
                success = SendGradientRect(cl, x, y, w, h);
            }
        } else {
            success = SendFullColorRect(cl, x, y, w, h);
        }
        break;
    case 1:
        /* Solid rectangle */
        success = SendSolidRect(cl);
        break;
    case 2:
        /* Two-color rectangle */
        success = SendMonoRect(cl, x, y, w, h);
        break;
    default:
        /* Up to 256 different colors */
        if ( paletteNumColors > 96 &&
             qualityLevel != -1 && qualityLevel <= 3 &&
             DetectSmoothImage(cl, &cl->format, w, h) ) {
            success = SendJpegRect(cl, x, y, w, h,
                                   tightConf[qualityLevel].jpegQuality);
        } else {
            success = SendIndexedRect(cl, x, y, w, h);
        }
    }
    return success;
}

static rfbBool
SendTightHeader(rfbClientPtr cl,
                int x,
                int y,
                int w,
                int h)
{
    rfbFramebufferUpdateRectHeader rect;

    if (cl->ublen + sz_rfbFramebufferUpdateRectHeader > 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(cl->tightEncoding);

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

    rfbStatRecordEncodingSent(cl, cl->tightEncoding, sz_rfbFramebufferUpdateRectHeader,
                              sz_rfbFramebufferUpdateRectHeader + w * (cl->format.bitsPerPixel / 8) * h);

    return TRUE;
}

/*
 * Subencoding implementations.
 */

static rfbBool
SendSolidRect(rfbClientPtr cl)
{
    int len;

    if (usePixelFormat24) {
        Pack24(cl, tightBeforeBuf, &cl->format, 1);
        len = 3;
    } else
        len = cl->format.bitsPerPixel / 8;

    if (cl->ublen + 1 + len > UPDATE_BUF_SIZE) {
        if (!rfbSendUpdateBuf(cl))
            return FALSE;
    }

    cl->updateBuf[cl->ublen++] = (char)(rfbTightFill << 4);
    memcpy (&cl->updateBuf[cl->ublen], tightBeforeBuf, len);
    cl->ublen += len;

    rfbStatRecordEncodingSentAdd(cl, cl->tightEncoding, len+1);

    return TRUE;
}

static rfbBool
SendMonoRect(rfbClientPtr cl,
             int x,
             int y,
             int w,
             int h)
{
    int streamId = 1;
    int paletteLen, dataLen;

#ifdef LIBVNCSERVER_HAVE_LIBPNG
    if (CanSendPngRect(cl, w, h)) {
        /* TODO: setup palette maybe */
        return SendPngRect(cl, x, y, w, h);
        /* TODO: destroy palette maybe */
    }
#endif

    if ( cl->ublen + TIGHT_MIN_TO_COMPRESS + 6 +
	 2 * cl->format.bitsPerPixel / 8 > UPDATE_BUF_SIZE ) {
        if (!rfbSendUpdateBuf(cl))
            return FALSE;
    }

    /* Prepare tight encoding header. */
    dataLen = (w + 7) / 8;
    dataLen *= h;

    cl->updateBuf[cl->ublen++] = (streamId | rfbTightExplicitFilter) << 4;
    cl->updateBuf[cl->ublen++] = rfbTightFilterPalette;
    cl->updateBuf[cl->ublen++] = 1;

    /* Prepare palette, convert image. */
    switch (cl->format.bitsPerPixel) {

    case 32:
        EncodeMonoRect32((uint8_t *)tightBeforeBuf, w, h);

        ((uint32_t *)tightAfterBuf)[0] = monoBackground;
        ((uint32_t *)tightAfterBuf)[1] = monoForeground;
        if (usePixelFormat24) {
            Pack24(cl, tightAfterBuf, &cl->format, 2);
            paletteLen = 6;
        } else
            paletteLen = 8;

        memcpy(&cl->updateBuf[cl->ublen], tightAfterBuf, paletteLen);
        cl->ublen += paletteLen;
        rfbStatRecordEncodingSentAdd(cl, cl->tightEncoding, 3 + paletteLen);
        break;

    case 16:
        EncodeMonoRect16((uint8_t *)tightBeforeBuf, w, h);

        ((uint16_t *)tightAfterBuf)[0] = (uint16_t)monoBackground;
        ((uint16_t *)tightAfterBuf)[1] = (uint16_t)monoForeground;

        memcpy(&cl->updateBuf[cl->ublen], tightAfterBuf, 4);
        cl->ublen += 4;
        rfbStatRecordEncodingSentAdd(cl, cl->tightEncoding, 7);
        break;

    default:
        EncodeMonoRect8((uint8_t *)tightBeforeBuf, w, h);

        cl->updateBuf[cl->ublen++] = (char)monoBackground;
        cl->updateBuf[cl->ublen++] = (char)monoForeground;
        rfbStatRecordEncodingSentAdd(cl, cl->tightEncoding, 5);
    }

    return CompressData(cl, streamId, dataLen,
                        tightConf[compressLevel].monoZlibLevel,
                        Z_DEFAULT_STRATEGY);
}

static rfbBool
SendIndexedRect(rfbClientPtr cl,
                int x,
                int y,
                int w,
                int h)
{
    int streamId = 2;
    int i, entryLen;

#ifdef LIBVNCSERVER_HAVE_LIBPNG
    if (CanSendPngRect(cl, w, h)) {
        return SendPngRect(cl, x, y, w, h);
    }
#endif

    if ( cl->ublen + TIGHT_MIN_TO_COMPRESS + 6 +
	 paletteNumColors * cl->format.bitsPerPixel / 8 >
         UPDATE_BUF_SIZE ) {
        if (!rfbSendUpdateBuf(cl))
            return FALSE;
    }

    /* Prepare tight encoding header. */
    cl->updateBuf[cl->ublen++] = (streamId | rfbTightExplicitFilter) << 4;
    cl->updateBuf[cl->ublen++] = rfbTightFilterPalette;
    cl->updateBuf[cl->ublen++] = (char)(paletteNumColors - 1);

    /* Prepare palette, convert image. */
    switch (cl->format.bitsPerPixel) {

    case 32:
        EncodeIndexedRect32((uint8_t *)tightBeforeBuf, w * h);

        for (i = 0; i < paletteNumColors; i++) {
            ((uint32_t *)tightAfterBuf)[i] =
                palette.entry[i].listNode->rgb;
        }
        if (usePixelFormat24) {
            Pack24(cl, tightAfterBuf, &cl->format, paletteNumColors);
            entryLen = 3;
        } else
            entryLen = 4;

        memcpy(&cl->updateBuf[cl->ublen], tightAfterBuf, paletteNumColors * entryLen);
        cl->ublen += paletteNumColors * entryLen;
        rfbStatRecordEncodingSentAdd(cl, cl->tightEncoding, 3 + paletteNumColors * entryLen);
        break;

    case 16:
        EncodeIndexedRect16((uint8_t *)tightBeforeBuf, w * h);

        for (i = 0; i < paletteNumColors; i++) {
            ((uint16_t *)tightAfterBuf)[i] =
                (uint16_t)palette.entry[i].listNode->rgb;
        }

        memcpy(&cl->updateBuf[cl->ublen], tightAfterBuf, paletteNumColors * 2);
        cl->ublen += paletteNumColors * 2;
        rfbStatRecordEncodingSentAdd(cl, cl->tightEncoding, 3 + paletteNumColors * 2);
        break;

    default:
        return FALSE;           /* Should never happen. */
    }

    return CompressData(cl, streamId, w * h,
                        tightConf[compressLevel].idxZlibLevel,
                        Z_DEFAULT_STRATEGY);
}

static rfbBool
SendFullColorRect(rfbClientPtr cl,
                  int x,
                  int y,
                  int w,
                  int h)
{
    int streamId = 0;
    int len;

#ifdef LIBVNCSERVER_HAVE_LIBPNG
    if (CanSendPngRect(cl, w, h)) {
        return SendPngRect(cl, x, y, w, h);
    }
#endif

    if (cl->ublen + TIGHT_MIN_TO_COMPRESS + 1 > UPDATE_BUF_SIZE) {
        if (!rfbSendUpdateBuf(cl))
            return FALSE;
    }

    cl->updateBuf[cl->ublen++] = 0x00;  /* stream id = 0, no flushing, no filter */
    rfbStatRecordEncodingSentAdd(cl, cl->tightEncoding, 1);

    if (usePixelFormat24) {
        Pack24(cl, tightBeforeBuf, &cl->format, w * h);
        len = 3;
    } else
        len = cl->format.bitsPerPixel / 8;

    return CompressData(cl, streamId, w * h * len,
                        tightConf[compressLevel].rawZlibLevel,
                        Z_DEFAULT_STRATEGY);
}