Archipelago » qemu

/*

 * QEMU VNC display driver: tight encoding

 *

 * From libvncserver/libvncserver/tight.c

 * Copyright (C) 2000, 2001 Const Kaplinsky.  All Rights Reserved.

 * Copyright (C) 1999 AT&T Laboratories Cambridge.  All Rights Reserved.

 *

 * Copyright (C) 2010 Corentin Chary <corentin.chary@gmail.com>

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL

 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

 * THE SOFTWARE.

 */

#include "qdict.h"

#include "qint.h"

#include "vnc.h"

#include "vnc-encoding-tight.h"

/* 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). */

static const struct {

    int max_rect_size, max_rect_width;

    int mono_min_rect_size, gradient_min_rect_size;

    int idx_zlib_level, mono_zlib_level, raw_zlib_level, gradient_zlib_level;

    int gradient_threshold, gradient_threshold24;

    int idx_max_colors_divisor;

    int jpeg_quality, jpeg_threshold, jpeg_threshold24;

} tight_conf[] = {

    {   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 }

};

/*

 * Code to determine how many different colors used in rectangle.

 */

static void tight_palette_rgb2buf(uint32_t rgb, int bpp, uint8_t buf[6])

{

    memset(buf, 0, 6);

    if (bpp == 32) {

        buf[0] = ((rgb >> 24) & 0xFF);

        buf[1] = ((rgb >> 16) & 0xFF);

        buf[2] = ((rgb >>  8) & 0xFF);

        buf[3] = ((rgb >>  0) & 0xFF);

        buf[4] = ((buf[0] & 1) == 0) << 3 | ((buf[1] & 1) == 0) << 2;

        buf[4]|= ((buf[2] & 1) == 0) << 1 | ((buf[3] & 1) == 0) << 0;

        buf[0] |= 1;

        buf[1] |= 1;

        buf[2] |= 1;

        buf[3] |= 1;

    }

    if (bpp == 16) {

        buf[0] = ((rgb >> 8) & 0xFF);

        buf[1] = ((rgb >> 0) & 0xFF);

        buf[2] = ((buf[0] & 1) == 0) << 1 | ((buf[1] & 1) == 0) << 0;

        buf[0] |= 1;

        buf[1] |= 1;

    }

}

static uint32_t tight_palette_buf2rgb(int bpp, const uint8_t *buf)

{

    uint32_t rgb = 0;

    if (bpp == 32) {

        rgb |= ((buf[0] & ~1) | !((buf[4] >> 3) & 1)) << 24;

        rgb |= ((buf[1] & ~1) | !((buf[4] >> 2) & 1)) << 16;

        rgb |= ((buf[2] & ~1) | !((buf[4] >> 1) & 1)) <<  8;

        rgb |= ((buf[3] & ~1) | !((buf[4] >> 0) & 1)) <<  0;

    }

    if (bpp == 16) {

        rgb |= ((buf[0] & ~1) | !((buf[2] >> 1) & 1)) << 8;

        rgb |= ((buf[1] & ~1) | !((buf[2] >> 0) & 1)) << 0;

    }

    return rgb;

}

static int tight_palette_insert(QDict *palette, uint32_t rgb, int bpp, int max)

{

    uint8_t key[6];

    int idx = qdict_size(palette);

    bool present;

    tight_palette_rgb2buf(rgb, bpp, key);

    present = qdict_haskey(palette, (char *)key);

    if (idx >= max && !present) {

        return 0;

    }

    if (!present) {

        qdict_put(palette, (char *)key, qint_from_int(idx));

    }

    return qdict_size(palette);

}

#define DEFINE_FILL_PALETTE_FUNCTION(bpp)                               \

                                                                        \

    static int                                                          \

    tight_fill_palette##bpp(VncState *vs, int x, int y,                 \

                            int max, size_t count,                      \

                            uint32_t *bg, uint32_t *fg,                 \

                            struct QDict **palette) {                   \

        uint##bpp##_t *data;                                            \

        uint##bpp##_t c0, c1, ci;                                       \

        int i, n0, n1;                                                  \

                                                                        \

        data = (uint##bpp##_t *)vs->tight.buffer;                       \

                                                                        \

        c0 = data[0];                                                   \

        i = 1;                                                          \

        while (i < count && data[i] == c0)                              \

            i++;                                                        \

        if (i >= count) {                                               \

            *bg = *fg = c0;                                             \

            return 1;                                                   \

        }                                                               \

                                                                        \

        if (max < 2) {                                                  \

            return 0;                                                   \

        }                                                               \

                                                                        \

        n0 = i;                                                         \

        c1 = data[i];                                                   \

        n1 = 0;                                                         \

        for (i++; i < count; i++) {                                     \

            ci = data[i];                                               \

            if (ci == c0) {                                             \

                n0++;                                                   \

            } else if (ci == c1) {                                      \

                n1++;                                                   \

            } else                                                      \

                break;                                                  \

        }                                                               \

        if (i >= count) {                                               \

            if (n0 > n1) {                                              \

                *bg = (uint32_t)c0;                                     \

                *fg = (uint32_t)c1;                                     \

            } else {                                                    \

                *bg = (uint32_t)c1;                                     \

                *fg = (uint32_t)c0;                                     \

            }                                                           \

            return 2;                                                   \

        }                                                               \

                                                                        \

        if (max == 2) {                                                 \

            return 0;                                                   \

        }                                                               \

                                                                        \

        *palette = qdict_new();                                         \

        tight_palette_insert(*palette, c0, bpp, max);                   \

        tight_palette_insert(*palette, c1, bpp, max);                   \

        tight_palette_insert(*palette, ci, bpp, max);                   \

                                                                        \

        for (i++; i < count; i++) {                                     \

            if (data[i] == ci) {                                        \

                continue;                                               \

            } else {                                                    \

                if (!tight_palette_insert(*palette, (uint32_t)ci,       \

                                          bpp, max)) {                  \

                    return 0;                                           \

                }                                                       \

                ci = data[i];                                           \

            }                                                           \

        }                                                               \

                                                                        \

        return qdict_size(*palette);                                    \

    }

DEFINE_FILL_PALETTE_FUNCTION(8)

DEFINE_FILL_PALETTE_FUNCTION(16)

DEFINE_FILL_PALETTE_FUNCTION(32)

static int tight_fill_palette(VncState *vs, int x, int y,

                              size_t count, uint32_t *bg, uint32_t *fg,

                              struct QDict **palette)

{

    int max;

    max = count / tight_conf[vs->tight_compression].idx_max_colors_divisor;

    if (max < 2 &&

        count >= tight_conf[vs->tight_compression].mono_min_rect_size) {

        max = 2;

    }

    if (max >= 256) {

        max = 256;

    }

    switch(vs->clientds.pf.bytes_per_pixel) {

    case 4:

        return tight_fill_palette32(vs, x, y, max, count, bg, fg, palette);

    case 2:

        return tight_fill_palette16(vs, x, y, max, count, bg, fg, palette);

    default:

        max = 2;

        return tight_fill_palette8(vs, x, y, max, count, bg, fg, palette);

    }

    return 0;

}

/* Callback to dump a palette with qdict_iter

static void print_palette(const char *key, QObject *obj, void *opaque)

{

    uint8_t idx = qint_get_int(qobject_to_qint(obj));

    uint32_t rgb = tight_palette_buf2rgb(32, (uint8_t *)key);

    fprintf(stderr, "%.2x ", (unsigned char)*key);

    while (*key++)

        fprintf(stderr, "%.2x ", (unsigned char)*key);

    fprintf(stderr, ": idx: %x rgb: %x\n", idx, rgb);

}

*/

/*

 * Converting truecolor samples into palette indices.

 */

#define DEFINE_IDX_ENCODE_FUNCTION(bpp)                                 \

                                                                        \

    static void                                                         \

    tight_encode_indexed_rect##bpp(uint8_t *buf, int count,             \

                                   struct QDict *palette) {             \

        uint##bpp##_t *src;                                             \

        uint##bpp##_t rgb;                                              \

        uint8_t key[6];                                                 \

        int i, rep;                                                     \

        uint8_t idx;                                                    \

                                                                        \

        src = (uint##bpp##_t *) buf;                                    \

                                                                        \

        for (i = 0; i < count; i++) {                                   \

            rgb = *src++;                                               \

            rep = 0;                                                    \

            while (i < count && *src == rgb) {                          \

                rep++, src++, i++;                                      \

            }                                                           \

            tight_palette_rgb2buf(rgb, bpp, key);                       \

            if (!qdict_haskey(palette, (char *)key)) {                  \

                /*                                                      \

                 * Should never happen, but don't break everything      \

                 * if it does, use the first color instead              \

                 */                                                     \

                idx = 0;                                                \

            } else {                                                    \

                idx = qdict_get_int(palette, (char *)key);              \

            }                                                           \

            while (rep >= 0) {                                          \

                *buf++ = idx;                                           \

                rep--;                                                  \

            }                                                           \

        }                                                               \

    }

DEFINE_IDX_ENCODE_FUNCTION(16)

DEFINE_IDX_ENCODE_FUNCTION(32)

#define DEFINE_MONO_ENCODE_FUNCTION(bpp)                                \

                                                                        \

    static void                                                         \

    tight_encode_mono_rect##bpp(uint8_t *buf, int w, int h,             \

                                uint##bpp##_t bg, uint##bpp##_t fg) {   \

        uint##bpp##_t *ptr;                                             \

        unsigned int value, mask;                                       \

        int aligned_width;                                              \

        int x, y, bg_bits;                                              \

                                                                        \

        ptr = (uint##bpp##_t *) buf;                                    \

        aligned_width = w - w % 8;                                      \

                                                                        \

        for (y = 0; y < h; y++) {                                       \

            for (x = 0; x < aligned_width; x += 8) {                    \

                for (bg_bits = 0; bg_bits < 8; bg_bits++) {             \

                    if (*ptr++ != bg) {                                 \

                        break;                                          \

                    }                                                   \

                }                                                       \

                if (bg_bits == 8) {                                     \

                    *buf++ = 0;                                         \

                    continue;                                           \

                }                                                       \

                mask = 0x80 >> bg_bits;                                 \

                value = mask;                                           \

                for (bg_bits++; bg_bits < 8; bg_bits++) {               \

                    mask >>= 1;                                         \

                    if (*ptr++ != bg) {                                 \

                        value |= mask;                                  \

                    }                                                   \

                }                                                       \

                *buf++ = (uint8_t)value;                                \

            }                                                           \

                                                                        \

            mask = 0x80;                                                \

            value = 0;                                                  \

            if (x >= w) {                                               \

                continue;                                               \

            }                                                           \

                                                                        \

            for (; x < w; x++) {                                        \

                if (*ptr++ != bg) {                                     \

                    value |= mask;                                      \

                }                                                       \

                mask >>= 1;                                             \

            }                                                           \

            *buf++ = (uint8_t)value;                                    \

        }                                                               \

    }

DEFINE_MONO_ENCODE_FUNCTION(8)

DEFINE_MONO_ENCODE_FUNCTION(16)

DEFINE_MONO_ENCODE_FUNCTION(32)

/*

 * 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.

 */

#define DEFINE_CHECK_SOLID_FUNCTION(bpp)                                \

                                                                        \

    static bool                                                         \

    check_solid_tile##bpp(VncState *vs, int x, int y, int w, int h,     \

                          uint32_t* color, bool samecolor)              \

    {                                                                   \

        VncDisplay *vd = vs->vd;                                        \

        uint##bpp##_t *fbptr;                                           \

        uint##bpp##_t c;                                                \

        int dx, dy;                                                     \

                                                                        \

        fbptr = (uint##bpp##_t *)                                       \

            (vd->server->data + y * ds_get_linesize(vs->ds) +           \

             x * ds_get_bytes_per_pixel(vs->ds));                       \

                                                                        \

        c = *fbptr;                                                     \

        if (samecolor && (uint32_t)c != *color) {                       \

            return false;                                               \

        }                                                               \

                                                                        \

        for (dy = 0; dy < h; dy++) {                                    \

            for (dx = 0; dx < w; dx++) {                                \

                if (c != fbptr[dx]) {                                   \

                    return false;                                       \

                }                                                       \

            }                                                           \

            fbptr = (uint##bpp##_t *)                                   \

                ((uint8_t *)fbptr + ds_get_linesize(vs->ds));           \

        }                                                               \

                                                                        \

        *color = (uint32_t)c;                                           \

        return true;                                                    \

    }

DEFINE_CHECK_SOLID_FUNCTION(32)

DEFINE_CHECK_SOLID_FUNCTION(16)

DEFINE_CHECK_SOLID_FUNCTION(8)

static bool check_solid_tile(VncState *vs, int x, int y, int w, int h,

                             uint32_t* color, bool samecolor)

{

    VncDisplay *vd = vs->vd;

    switch(vd->server->pf.bytes_per_pixel) {

    case 4:

        return check_solid_tile32(vs, x, y, w, h, color, samecolor);

    case 2:

        return check_solid_tile16(vs, x, y, w, h, color, samecolor);

    default:

        return check_solid_tile8(vs, x, y, w, h, color, samecolor);

    }

}

static void find_best_solid_area(VncState *vs, int x, int y, int w, int h,

                                 uint32_t color, 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 += VNC_TIGHT_MAX_SPLIT_TILE_SIZE) {

        dh = MIN(VNC_TIGHT_MAX_SPLIT_TILE_SIZE, y + h - dy);

        dw = MIN(VNC_TIGHT_MAX_SPLIT_TILE_SIZE, w_prev);

        if (!check_solid_tile(vs, x, dy, dw, dh, &color, true)) {

            break;

        }

        for (dx = x + dw; dx < x + w_prev;) {

            dw = MIN(VNC_TIGHT_MAX_SPLIT_TILE_SIZE, x + w_prev - dx);

            if (!check_solid_tile(vs, dx, dy, dw, dh, &color, 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 extend_solid_area(VncState *vs, int x, int y, int w, int h,

                              uint32_t color, 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 && check_solid_tile(vs, *x_ptr, cy, *w_ptr, 1, &color, true);

          cy-- );

    *h_ptr += *y_ptr - (cy + 1);

    *y_ptr = cy + 1;

    /* ... downwards. */

    for ( cy = *y_ptr + *h_ptr;

          cy < y + h &&

              check_solid_tile(vs, *x_ptr, cy, *w_ptr, 1, &color, true);

          cy++ );

    *h_ptr += cy - (*y_ptr + *h_ptr);

    /* ... to the left. */

    for ( cx = *x_ptr - 1;

          cx >= x && check_solid_tile(vs, cx, *y_ptr, 1, *h_ptr, &color, true);

          cx-- );

    *w_ptr += *x_ptr - (cx + 1);

    *x_ptr = cx + 1;

    /* ... to the right. */

    for ( cx = *x_ptr + *w_ptr;

          cx < x + w &&

              check_solid_tile(vs, cx, *y_ptr, 1, *h_ptr, &color, true);

          cx++ );

    *w_ptr += cx - (*x_ptr + *w_ptr);

}

static int tight_init_stream(VncState *vs, int stream_id,

                             int level, int strategy)

{

    z_streamp zstream = &vs->tight_stream[stream_id];

    if (zstream->opaque == NULL) {

        int err;

        VNC_DEBUG("VNC: TIGHT: initializing zlib stream %d\n", stream_id);

        VNC_DEBUG("VNC: TIGHT: opaque = %p | vs = %p\n", zstream->opaque, vs);

        zstream->zalloc = vnc_zlib_zalloc;

        zstream->zfree = vnc_zlib_zfree;

        err = deflateInit2(zstream, level, Z_DEFLATED, MAX_WBITS,

                           MAX_MEM_LEVEL, strategy);

        if (err != Z_OK) {

            fprintf(stderr, "VNC: error initializing zlib\n");

            return -1;

        }

        vs->tight_levels[stream_id] = level;

        zstream->opaque = vs;

    }

    if (vs->tight_levels[stream_id] != level) {

        if (deflateParams(zstream, level, strategy) != Z_OK) {

            return -1;

        }

        vs->tight_levels[stream_id] = level;

    }

    return 0;

}

static void tight_send_compact_size(VncState *vs, size_t len)

{

    int lpc = 0;

    int bytes = 0;

    char buf[3] = {0, 0, 0};

    buf[bytes++] = len & 0x7F;

    if (len > 0x7F) {

        buf[bytes-1] |= 0x80;

        buf[bytes++] = (len >> 7) & 0x7F;

        if (len > 0x3FFF) {

            buf[bytes-1] |= 0x80;

            buf[bytes++] = (len >> 14) & 0xFF;

        }

    }

    for (lpc = 0; lpc < bytes; lpc++) {

        vnc_write_u8(vs, buf[lpc]);

    }

}

static int tight_compress_data(VncState *vs, int stream_id, size_t bytes,

                               int level, int strategy)

{

    z_streamp zstream = &vs->tight_stream[stream_id];

    int previous_out;

    if (bytes < VNC_TIGHT_MIN_TO_COMPRESS) {

        vnc_write(vs, vs->tight.buffer, vs->tight.offset);

        return bytes;

    }

    if (tight_init_stream(vs, stream_id, level, strategy)) {

        return -1;

    }

    /* reserve memory in output buffer */

    buffer_reserve(&vs->tight_zlib, bytes + 64);

    /* set pointers */

    zstream->next_in = vs->tight.buffer;

    zstream->avail_in = vs->tight.offset;

    zstream->next_out = vs->tight_zlib.buffer + vs->tight_zlib.offset;

    zstream->avail_out = vs->tight_zlib.capacity - vs->tight_zlib.offset;

    zstream->data_type = Z_BINARY;

    previous_out = zstream->total_out;

    /* start encoding */

    if (deflate(zstream, Z_SYNC_FLUSH) != Z_OK) {

        fprintf(stderr, "VNC: error during tight compression\n");

        return -1;

    }

    vs->tight_zlib.offset = vs->tight_zlib.capacity - zstream->avail_out;

    bytes = zstream->total_out - previous_out;

    tight_send_compact_size(vs, bytes);

    vnc_write(vs, vs->tight_zlib.buffer, bytes);

    buffer_reset(&vs->tight_zlib);

    return bytes;

}

/*

 * Subencoding implementations.

 */

static void tight_pack24(VncState *vs, uint8_t *buf, size_t count, size_t *ret)

{

    uint32_t *buf32;

    uint32_t pix;

    int rshift, gshift, bshift;

    buf32 = (uint32_t *)buf;

    if ((vs->clientds.flags & QEMU_BIG_ENDIAN_FLAG) ==

        (vs->ds->surface->flags & QEMU_BIG_ENDIAN_FLAG)) {

        rshift = vs->clientds.pf.rshift;

        gshift = vs->clientds.pf.gshift;

        bshift = vs->clientds.pf.bshift;

    } else {

        rshift = 24 - vs->clientds.pf.rshift;

        gshift = 24 - vs->clientds.pf.gshift;

        bshift = 24 - vs->clientds.pf.bshift;

    }

    if (ret) {

        *ret = count * 3;

    }

    while (count--) {

        pix = *buf32++;

        *buf++ = (char)(pix >> rshift);

        *buf++ = (char)(pix >> gshift);

        *buf++ = (char)(pix >> bshift);

    }

}

static int send_full_color_rect(VncState *vs, int w, int h)

{

    int stream = 0;

    size_t bytes;

    vnc_write_u8(vs, stream << 4); /* no flushing, no filter */

    if (vs->tight_pixel24) {

        tight_pack24(vs, vs->tight.buffer, w * h, &vs->tight.offset);

        bytes = 3;

    } else {

        bytes = vs->clientds.pf.bytes_per_pixel;

    }

    bytes = tight_compress_data(vs, stream, w * h * bytes,

                                tight_conf[vs->tight_compression].raw_zlib_level,

                                Z_DEFAULT_STRATEGY);

    return (bytes >= 0);

}

static int send_solid_rect(VncState *vs)

{

    size_t bytes;

    vnc_write_u8(vs, VNC_TIGHT_FILL << 4); /* no flushing, no filter */

    if (vs->tight_pixel24) {

        tight_pack24(vs, vs->tight.buffer, 1, &vs->tight.offset);

        bytes = 3;

    } else {

        bytes = vs->clientds.pf.bytes_per_pixel;

    }

    vnc_write(vs, vs->tight.buffer, bytes);

    return 1;

}

static int send_mono_rect(VncState *vs, int w, int h, uint32_t bg, uint32_t fg)

{

    size_t bytes;

    int stream = 1;

    int level = tight_conf[vs->tight_compression].mono_zlib_level;

    bytes = ((w + 7) / 8) * h;

    vnc_write_u8(vs, (stream | VNC_TIGHT_EXPLICIT_FILTER) << 4);

    vnc_write_u8(vs, VNC_TIGHT_FILTER_PALETTE);

    vnc_write_u8(vs, 1);

    switch(vs->clientds.pf.bytes_per_pixel) {

    case 4:

    {

        uint32_t buf[2] = {bg, fg};

        size_t ret = sizeof (buf);

        if (vs->tight_pixel24) {

            tight_pack24(vs, (unsigned char*)buf, 2, &ret);

        }

        vnc_write(vs, buf, ret);

        tight_encode_mono_rect32(vs->tight.buffer, w, h, bg, fg);

        break;

    }

    case 2:

        vnc_write(vs, &bg, 2);

        vnc_write(vs, &fg, 2);

        tight_encode_mono_rect16(vs->tight.buffer, w, h, bg, fg);

        break;

    default:

        vnc_write_u8(vs, bg);

        vnc_write_u8(vs, fg);

        tight_encode_mono_rect8(vs->tight.buffer, w, h, bg, fg);

        break;

    }

    vs->tight.offset = bytes;

    bytes = tight_compress_data(vs, stream, bytes, level, Z_DEFAULT_STRATEGY);

    return (bytes >= 0);

}

struct palette_cb_priv {

    VncState *vs;

    uint8_t *header;

};

static void write_palette(const char *key, QObject *obj, void *opaque)

{

    struct palette_cb_priv *priv = opaque;

    VncState *vs = priv->vs;

    uint32_t bytes = vs->clientds.pf.bytes_per_pixel;

    uint8_t idx = qint_get_int(qobject_to_qint(obj));

    if (bytes == 4) {

        uint32_t color = tight_palette_buf2rgb(32, (uint8_t *)key);

        ((uint32_t*)priv->header)[idx] = color;

    } else {

        uint16_t color = tight_palette_buf2rgb(16, (uint8_t *)key);

        ((uint16_t*)priv->header)[idx] = color;

    }

}

static int send_palette_rect(VncState *vs, int w, int h, struct QDict *palette)

{

    int stream = 2;

    int level = tight_conf[vs->tight_compression].idx_zlib_level;

    int colors;

    size_t bytes;

    colors = qdict_size(palette);

    vnc_write_u8(vs, (stream | VNC_TIGHT_EXPLICIT_FILTER) << 4);

    vnc_write_u8(vs, VNC_TIGHT_FILTER_PALETTE);

    vnc_write_u8(vs, colors - 1);

    switch(vs->clientds.pf.bytes_per_pixel) {

    case 4:

    {

        size_t old_offset, offset;

        uint32_t header[qdict_size(palette)];

        struct palette_cb_priv priv = { vs, (uint8_t *)header };

        old_offset = vs->output.offset;

        qdict_iter(palette, write_palette, &priv);

        vnc_write(vs, header, sizeof(header));

        if (vs->tight_pixel24) {

            tight_pack24(vs, vs->output.buffer + old_offset, colors, &offset);

            vs->output.offset = old_offset + offset;

        }

        tight_encode_indexed_rect32(vs->tight.buffer, w * h, palette);

        break;

    }

    case 2:

    {

        uint16_t header[qdict_size(palette)];

        struct palette_cb_priv priv = { vs, (uint8_t *)header };

        qdict_iter(palette, write_palette, &priv);

        vnc_write(vs, header, sizeof(header));

        tight_encode_indexed_rect16(vs->tight.buffer, w * h, palette);

        break;

    }

    default:

        return -1; /* No palette for 8bits colors */

        break;

    }

    bytes = w * h;

    vs->tight.offset = bytes;

    bytes = tight_compress_data(vs, stream, bytes,

                                level, Z_DEFAULT_STRATEGY);

    return (bytes >= 0);

}

static void vnc_tight_start(VncState *vs)

{

    buffer_reset(&vs->tight);

    // make the output buffer be the zlib buffer, so we can compress it later

    vs->tight_tmp = vs->output;

    vs->output = vs->tight;

}

static void vnc_tight_stop(VncState *vs)

{

    // switch back to normal output/zlib buffers

    vs->tight = vs->output;

    vs->output = vs->tight_tmp;

}

static int send_sub_rect(VncState *vs, int x, int y, int w, int h)

{

    struct QDict *palette = NULL;

    uint32_t bg = 0, fg = 0;

    int colors;

    int ret = 0;

    vnc_framebuffer_update(vs, x, y, w, h, VNC_ENCODING_TIGHT);

    vnc_tight_start(vs);

    vnc_raw_send_framebuffer_update(vs, x, y, w, h);

    vnc_tight_stop(vs);

    colors = tight_fill_palette(vs, x, y, w * h, &fg, &bg, &palette);

    if (colors == 0) {

        ret = send_full_color_rect(vs, w, h);

    } else if (colors == 1) {

        ret = send_solid_rect(vs);

    } else if (colors == 2) {

        ret = send_mono_rect(vs, w, h, bg, fg);

    } else if (colors <= 256) {

        ret = send_palette_rect(vs, w, h, palette);

    }

    QDECREF(palette);

    return ret;

}

static int send_sub_rect_solid(VncState *vs, int x, int y, int w, int h)

{

    vnc_framebuffer_update(vs, x, y, w, h, VNC_ENCODING_TIGHT);

    vnc_tight_start(vs);

    vnc_raw_send_framebuffer_update(vs, x, y, w, h);

    vnc_tight_stop(vs);

    return send_solid_rect(vs);

}

static int send_rect_simple(VncState *vs, int x, int y, int w, int h)

{

    int max_size, max_width;

    int max_sub_width, max_sub_height;

    int dx, dy;

    int rw, rh;

    int n = 0;

    max_size = tight_conf[vs->tight_compression].max_rect_size;

    max_width = tight_conf[vs->tight_compression].max_rect_width;

    if (w > max_width || w * h > max_size) {

        max_sub_width = (w > max_width) ? max_width : w;

        max_sub_height = max_size / max_sub_width;

        for (dy = 0; dy < h; dy += max_sub_height) {

            for (dx = 0; dx < w; dx += max_width) {

                rw = MIN(max_sub_width, w - dx);

                rh = MIN(max_sub_height, h - dy);

                n += send_sub_rect(vs, x+dx, y+dy, rw, rh);

            }

        }

    } else {

        n += send_sub_rect(vs, x, y, w, h);

    }

    return n;

}

static int find_large_solid_color_rect(VncState *vs, int x, int y,

                                       int w, int h, int max_rows)

{

    int dx, dy, dw, dh;

    int n = 0;

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

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

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

        if (dy - y >= max_rows) {

            n += send_rect_simple(vs, x, y, w, max_rows);

            y += max_rows;

            h -= max_rows;

        }

        dh = MIN(VNC_TIGHT_MAX_SPLIT_TILE_SIZE, (y + h - dy));

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

            uint32_t color_value;

            int x_best, y_best, w_best, h_best;

            dw = MIN(VNC_TIGHT_MAX_SPLIT_TILE_SIZE, (x + w - dx));

            if (!check_solid_tile(vs, dx, dy, dw, dh, &color_value, false)) {

                continue ;

            }

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

            find_best_solid_area(vs, dx, dy, w - (dx - x), h - (dy - y),

                                 color_value, &w_best, &h_best);

            /* Make sure a solid rectangle is large enough