tight.c

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/*
 * 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.h"
#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. */
Bool rfbTightDisableGradient = FALSE;

/* This variable is set on every rfbSendRectEncodingTight() call. */
static Bool usePixelFormat24;


/* 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 }
};

static int compressLevel;
static int qualityLevel;

/* Stuff dealing with palettes. */

typedef struct COLOR_LIST_s {
    struct COLOR_LIST_s *next;
    int idx;
    CARD32 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;

static int paletteNumColors, paletteMaxColors;
static CARD32 monoBackground, monoForeground;
static PALETTE palette;

/* Pointers to dynamically-allocated buffers. */

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

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

static int *prevRowBuf = NULL;


/* Prototypes for static functions. */

static void FindBestSolidArea (int x, int y, int w, int h,
                               CARD32 colorValue, int *w_ptr, int *h_ptr);
static void ExtendSolidArea   (int x, int y, int w, int h,
                               CARD32 colorValue,
                               int *x_ptr, int *y_ptr, int *w_ptr, int *h_ptr);
static Bool CheckSolidTile    (int x, int y, int w, int h,
                               CARD32 *colorPtr, Bool needSameColor);
static Bool CheckSolidTile8   (int x, int y, int w, int h,
                               CARD32 *colorPtr, Bool needSameColor);
static Bool CheckSolidTile16  (int x, int y, int w, int h,
                               CARD32 *colorPtr, Bool needSameColor);
static Bool CheckSolidTile32  (int x, int y, int w, int h,
                               CARD32 *colorPtr, Bool needSameColor);

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

static Bool SendSolidRect     (rfbClientPtr cl);
static Bool SendMonoRect      (rfbClientPtr cl, int w, int h);
static Bool SendIndexedRect   (rfbClientPtr cl, int w, int h);
static Bool SendFullColorRect (rfbClientPtr cl, int w, int h);
static Bool SendGradientRect  (rfbClientPtr cl, int w, int h);

static Bool CompressData(rfbClientPtr cl, int streamId, int dataLen,
                         int zlibLevel, int zlibStrategy);
static Bool 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(CARD32 rgb, int numPixels, int bpp);

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

static void EncodeIndexedRect16(CARD8 *buf, int count);
static void EncodeIndexedRect32(CARD8 *buf, int count);

static void EncodeMonoRect8(CARD8 *buf, int w, int h);
static void EncodeMonoRect16(CARD8 *buf, int w, int h);
static void EncodeMonoRect32(CARD8 *buf, int w, int h);

static void FilterGradient24(char *buf, rfbPixelFormat *fmt, int w, int h);
static void FilterGradient16(CARD16 *buf, rfbPixelFormat *fmt, int w, int h);
static void FilterGradient32(CARD32 *buf, rfbPixelFormat *fmt, int w, int h);

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

static Bool SendJpegRect(rfbClientPtr cl, int x, int y, int w, int h,
                         int quality);
static void PrepareRowForJpeg(CARD8 *dst, int x, int y, int count);
static void PrepareRowForJpeg24(CARD8 *dst, int x, int y, int count);
static void PrepareRowForJpeg16(CARD8 *dst, int x, int y, int count);
static void PrepareRowForJpeg32(CARD8 *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);


/*
 * Tight encoding implementation.
 */

int
rfbNumCodedRectsTight(cl, x, y, w, h)
    rfbClientPtr cl;
    int x, y, w, 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;
    }
}

Bool
rfbSendRectEncodingTight(cl, x, y, w, h)
    rfbClientPtr cl;
    int x, y, w, h;
{
    int nMaxRows;
    CARD32 colorValue;
    int dx, dy, dw, dh;
    int x_best, y_best, w_best, h_best;
    char *fbptr;

    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 *)xalloc(tightBeforeBufSize);
        else
            tightBeforeBuf = (char *)xrealloc(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(dx, dy, dw, dh, &colorValue, FALSE)) {

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

                FindBestSolidArea(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(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 &&
                     !rfbSendRectEncodingTight(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 = (rfbScreen.pfbMemory +
                         (rfbScreen.paddedWidthInBytes * y_best) +
                         (x_best * (rfbScreen.bitsPerPixel / 8)));

                (*cl->translateFn)(cl->translateLookupTable, &rfbServerFormat,
                                   &cl->format, fbptr, tightBeforeBuf,
                                   rfbScreen.paddedWidthInBytes, 1, 1);

                if (!SendSolidRect(cl))
                    return FALSE;

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

                if ( x_best + w_best != x + w &&
                     !rfbSendRectEncodingTight(cl, x_best+w_best, y_best,
                                               w-(x_best-x)-w_best, h_best) )
                    return FALSE;
                if ( y_best + h_best != y + h &&
                     !rfbSendRectEncodingTight(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(x, y, w, h, colorValue, w_ptr, h_ptr)
    int x, y, w, h;