cscg24-guacamole

CSCG 2024 Challenge 'Guacamole Mashup'
git clone https://git.sinitax.com/sinitax/cscg24-guacamole
Log | Files | Refs | sfeed.txt

surface.c (62639B)


      1/*
      2 * Licensed to the Apache Software Foundation (ASF) under one
      3 * or more contributor license agreements.  See the NOTICE file
      4 * distributed with this work for additional information
      5 * regarding copyright ownership.  The ASF licenses this file
      6 * to you under the Apache License, Version 2.0 (the
      7 * "License"); you may not use this file except in compliance
      8 * with the License.  You may obtain a copy of the License at
      9 *
     10 *   http://www.apache.org/licenses/LICENSE-2.0
     11 *
     12 * Unless required by applicable law or agreed to in writing,
     13 * software distributed under the License is distributed on an
     14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
     15 * KIND, either express or implied.  See the License for the
     16 * specific language governing permissions and limitations
     17 * under the License.
     18 */
     19
     20#include "config.h"
     21#include "common/rect.h"
     22#include "common/surface.h"
     23
     24#include <cairo/cairo.h>
     25#include <guacamole/client.h>
     26#include <guacamole/layer.h>
     27#include <guacamole/mem.h>
     28#include <guacamole/protocol.h>
     29#include <guacamole/socket.h>
     30#include <guacamole/timestamp.h>
     31#include <guacamole/user.h>
     32
     33#include <pthread.h>
     34#include <stdlib.h>
     35#include <stdint.h>
     36#include <string.h>
     37
     38/**
     39 * The width of an update which should be considered negible and thus
     40 * trivial overhead compared ot the cost of two updates.
     41 */
     42#define GUAC_SURFACE_NEGLIGIBLE_WIDTH 64
     43
     44/**
     45 * The height of an update which should be considered negible and thus
     46 * trivial overhead compared ot the cost of two updates.
     47 */
     48#define GUAC_SURFACE_NEGLIGIBLE_HEIGHT 64
     49
     50/**
     51 * The proportional increase in cost contributed by transfer and processing of
     52 * image data, compared to processing an equivalent amount of client-side
     53 * data.
     54 */
     55#define GUAC_SURFACE_DATA_FACTOR 16
     56
     57/**
     58 * The base cost of every update. Each update should be considered to have
     59 * this starting cost, plus any additional cost estimated from its
     60 * content.
     61 */
     62#define GUAC_SURFACE_BASE_COST 4096
     63
     64/**
     65 * An increase in cost is negligible if it is less than
     66 * 1/GUAC_SURFACE_NEGLIGIBLE_INCREASE of the old cost.
     67 */
     68#define GUAC_SURFACE_NEGLIGIBLE_INCREASE 4
     69
     70/**
     71 * If combining an update because it appears to be follow a fill pattern,
     72 * the combined cost must not exceed
     73 * GUAC_SURFACE_FILL_PATTERN_FACTOR * (total uncombined cost).
     74 */
     75#define GUAC_SURFACE_FILL_PATTERN_FACTOR 3
     76
     77/* Define cairo_format_stride_for_width() if missing */
     78#ifndef HAVE_CAIRO_FORMAT_STRIDE_FOR_WIDTH
     79#define cairo_format_stride_for_width(format, width) (width*4)
     80#endif
     81
     82/**
     83 * The framerate which, if exceeded, indicates that JPEG is preferred.
     84 */
     85#define GUAC_COMMON_SURFACE_JPEG_FRAMERATE 3
     86
     87/**
     88 * Minimum JPEG bitmap size (area). If the bitmap is smaller than this threshold,
     89 * it should be compressed as a PNG image to avoid the JPEG compression tax.
     90 */
     91#define GUAC_SURFACE_JPEG_MIN_BITMAP_SIZE 4096
     92
     93/**
     94 * The JPEG compression min block size. This defines the optimal rectangle block
     95 * size factor for JPEG compression. Usually 8x8 would suffice, but use 16 to
     96 * reduce the occurrence of ringing artifacts further.
     97 */
     98#define GUAC_SURFACE_JPEG_BLOCK_SIZE 16
     99
    100/**
    101 * The WebP compression min block size. This defines the optimal rectangle block
    102 * size factor for WebP compression. WebP does utilize variable block size, but
    103 * ensuring a block size factor reduces any noise on the image edges.
    104 */
    105#define GUAC_SURFACE_WEBP_BLOCK_SIZE 8
    106
    107void guac_common_surface_set_multitouch(guac_common_surface* surface,
    108        int touches) {
    109
    110    pthread_mutex_lock(&surface->_lock);
    111
    112    surface->touches = touches;
    113    guac_protocol_send_set_int(surface->socket, surface->layer,
    114            GUAC_PROTOCOL_LAYER_PARAMETER_MULTI_TOUCH, touches);
    115
    116    pthread_mutex_unlock(&surface->_lock);
    117
    118}
    119
    120void guac_common_surface_set_lossless(guac_common_surface* surface,
    121        int lossless) {
    122
    123    pthread_mutex_lock(&surface->_lock);
    124    surface->lossless = lossless;
    125    pthread_mutex_unlock(&surface->_lock);
    126
    127}
    128
    129void guac_common_surface_move(guac_common_surface* surface, int x, int y) {
    130
    131    pthread_mutex_lock(&surface->_lock);
    132
    133    surface->x = x;
    134    surface->y = y;
    135    surface->location_dirty = 1;
    136
    137    pthread_mutex_unlock(&surface->_lock);
    138
    139}
    140
    141void guac_common_surface_stack(guac_common_surface* surface, int z) {
    142
    143    pthread_mutex_lock(&surface->_lock);
    144
    145    surface->z = z;
    146    surface->location_dirty = 1;
    147
    148    pthread_mutex_unlock(&surface->_lock);
    149
    150}
    151
    152void guac_common_surface_set_parent(guac_common_surface* surface,
    153        const guac_layer* parent) {
    154
    155    pthread_mutex_lock(&surface->_lock);
    156
    157    surface->parent = parent;
    158    surface->location_dirty = 1;
    159
    160    pthread_mutex_unlock(&surface->_lock);
    161
    162}
    163
    164void guac_common_surface_set_opacity(guac_common_surface* surface,
    165        int opacity) {
    166
    167    pthread_mutex_lock(&surface->_lock);
    168
    169    surface->opacity = opacity;
    170    surface->opacity_dirty = 1;
    171
    172    pthread_mutex_unlock(&surface->_lock);
    173
    174}
    175
    176/**
    177 * Updates the coordinates of the given rectangle to be within the bounds of
    178 * the given surface.
    179 *
    180 * @param surface The surface to use for clipping.
    181 * @param rect The rectangle to clip.
    182 * @param sx The X coordinate of the source rectangle, if any.
    183 * @param sy The Y coordinate of the source rectangle, if any.
    184 */
    185static void __guac_common_bound_rect(guac_common_surface* surface,
    186        guac_common_rect* rect, int* sx, int* sy) {
    187
    188    guac_common_rect bounds_rect = {
    189        .x = 0,
    190        .y = 0,
    191        .width  = surface->width,
    192        .height = surface->height
    193    };
    194
    195    int orig_x = rect->x;
    196    int orig_y = rect->y;
    197
    198    guac_common_rect_constrain(rect, &bounds_rect);
    199
    200    /* Update source X/Y if given */
    201    if (sx != NULL) *sx += rect->x - orig_x;
    202    if (sy != NULL) *sy += rect->y - orig_y;
    203
    204}
    205
    206/**
    207 * Updates the coordinates of the given rectangle to be within the clipping
    208 * rectangle of the given surface, which must always be within the bounding
    209 * rectangle of the given surface.
    210 *
    211 * @param surface The surface to use for clipping.
    212 * @param rect The rectangle to clip.
    213 * @param sx The X coordinate of the source rectangle, if any.
    214 * @param sy The Y coordinate of the source rectangle, if any.
    215 */
    216static void __guac_common_clip_rect(guac_common_surface* surface,
    217        guac_common_rect* rect, int* sx, int* sy) {
    218
    219    int orig_x = rect->x;
    220    int orig_y = rect->y;
    221
    222    /* Just bound within surface if no clipping rectangle applied */
    223    if (!surface->clipped) {
    224        __guac_common_bound_rect(surface, rect, sx, sy);
    225        return;
    226    }
    227
    228    guac_common_rect_constrain(rect, &surface->clip_rect);
    229
    230    /* Update source X/Y if given */
    231    if (sx != NULL) *sx += rect->x - orig_x;
    232    if (sy != NULL) *sy += rect->y - orig_y;
    233
    234}
    235
    236/**
    237 * Returns whether a rectangle within the given surface contains only fully
    238 * opaque pixels.
    239 *
    240 * @param surface
    241 *     The surface to check.
    242 *
    243 * @param rect
    244 *     The rectangle to check.
    245 *
    246 * @return
    247 *     Non-zero if the rectangle contains only fully opaque pixels, zero
    248 *     otherwise.
    249 */
    250static int __guac_common_surface_is_opaque(guac_common_surface* surface,
    251        guac_common_rect* rect) {
    252
    253    int x, y;
    254
    255    int stride = surface ->stride;
    256    unsigned char* buffer =
    257        surface->buffer + (stride * rect->y) + (4 * rect->x);
    258
    259    /* For each row */
    260    for (y = 0; y < rect->height; y++) {
    261
    262        /* Search for a non-opaque pixel */
    263        uint32_t* current = (uint32_t*) buffer;
    264        for (x=0; x < rect->width; x++) {
    265
    266            /* Rectangle is non-opaque if a single non-opaque pixel is found */
    267            uint32_t color = *(current++);
    268            if ((color & 0xFF000000) != 0xFF000000)
    269                return 0;
    270
    271        }
    272
    273        /* Next row */
    274        buffer += stride;
    275
    276    }
    277
    278    /* Rectangle is opaque */
    279    return 1;
    280
    281}
    282
    283
    284/**
    285 * Returns whether the given rectangle should be combined into the existing
    286 * dirty rectangle, to be eventually flushed as image data, or would be best
    287 * kept independent of the current rectangle.
    288 *
    289 * @param surface
    290 *     The surface being updated.
    291 *
    292 * @param rect
    293 *     The bounding rectangle of the update being made to the surface.
    294 *
    295 * @param rect_only
    296 *     Non-zero if this update, by its nature, contains only metainformation
    297 *     about the update's bounding rectangle, zero if the update also contains
    298 *     image data.
    299 *
    300 * @return
    301 *     Non-zero if the update should be combined with any existing update, zero
    302 *     otherwise.
    303 */
    304static int __guac_common_should_combine(guac_common_surface* surface, const guac_common_rect* rect, int rect_only) {
    305
    306    /* Always favor combining updates if surface is currently a purely
    307     * server-side scratch area */
    308    if (!surface->realized)
    309        return 1;
    310
    311    if (surface->dirty) {
    312
    313        int combined_cost, dirty_cost, update_cost;
    314
    315        /* Simulate combination */
    316        guac_common_rect combined = surface->dirty_rect;
    317        guac_common_rect_extend(&combined, rect);
    318
    319        /* Combine if result is still small */
    320        if (combined.width <= GUAC_SURFACE_NEGLIGIBLE_WIDTH && combined.height <= GUAC_SURFACE_NEGLIGIBLE_HEIGHT)
    321            return 1;
    322
    323        /* Estimate costs of the existing update, new update, and both combined */
    324        combined_cost = GUAC_SURFACE_BASE_COST + combined.width * combined.height;
    325        dirty_cost    = GUAC_SURFACE_BASE_COST + surface->dirty_rect.width * surface->dirty_rect.height;
    326        update_cost   = GUAC_SURFACE_BASE_COST + rect->width * rect->height;
    327
    328        /* Reduce cost if no image data */
    329        if (rect_only)
    330            update_cost /= GUAC_SURFACE_DATA_FACTOR;
    331
    332        /* Combine if cost estimate shows benefit */
    333        if (combined_cost <= update_cost + dirty_cost)
    334            return 1;
    335
    336        /* Combine if increase in cost is negligible */
    337        if (combined_cost - dirty_cost <= dirty_cost / GUAC_SURFACE_NEGLIGIBLE_INCREASE)
    338            return 1;
    339
    340        if (combined_cost - update_cost <= update_cost / GUAC_SURFACE_NEGLIGIBLE_INCREASE)
    341            return 1;
    342
    343        /* Combine if we anticipate further updates, as this update follows a common fill pattern */
    344        if (rect->x == surface->dirty_rect.x && rect->y == surface->dirty_rect.y + surface->dirty_rect.height) {
    345            if (combined_cost <= (dirty_cost + update_cost) * GUAC_SURFACE_FILL_PATTERN_FACTOR)
    346                return 1;
    347        }
    348
    349    }
    350    
    351    /* Otherwise, do not combine */
    352    return 0;
    353
    354}
    355
    356/**
    357 * Expands the dirty rect of the given surface to contain the rect described by the given
    358 * coordinates.
    359 *
    360 * @param surface The surface to mark as dirty.
    361 * @param rect The rectangle of the update which is dirtying the surface.
    362 */
    363static void __guac_common_mark_dirty(guac_common_surface* surface, const guac_common_rect* rect) {
    364
    365    /* Ignore empty rects */
    366    if (rect->width <= 0 || rect->height <= 0)
    367        return;
    368
    369    /* If already dirty, update existing rect */
    370    if (surface->dirty)
    371        guac_common_rect_extend(&surface->dirty_rect, rect);
    372
    373    /* Otherwise init dirty rect */
    374    else {
    375        surface->dirty_rect = *rect;
    376        surface->dirty = 1;
    377    }
    378
    379}
    380
    381/**
    382 * Calculate the current average framerate for a given area on the surface.
    383 *
    384 * @param surface
    385 *     The surface on which the framerate will be calculated.
    386 *
    387 * @param rect
    388 *     The rect containing the area for which the average framerate will be
    389 *     calculated.
    390 *
    391 * @return
    392 *     The average framerate of the given area, in frames per second.
    393 */
    394static unsigned int __guac_common_surface_calculate_framerate(
    395        guac_common_surface* surface, const guac_common_rect* rect) {
    396
    397    int x, y;
    398
    399    /* Calculate heat map dimensions */
    400    size_t heat_width = GUAC_COMMON_SURFACE_HEAT_DIMENSION(surface->width);
    401
    402    /* Calculate minimum X/Y coordinates intersecting given rect */
    403    int min_x = rect->x / GUAC_COMMON_SURFACE_HEAT_CELL_SIZE;
    404    int min_y = rect->y / GUAC_COMMON_SURFACE_HEAT_CELL_SIZE;
    405
    406    /* Calculate maximum X/Y coordinates intersecting given rect */
    407    int max_x = min_x + (rect->width  - 1) / GUAC_COMMON_SURFACE_HEAT_CELL_SIZE;
    408    int max_y = min_y + (rect->height - 1) / GUAC_COMMON_SURFACE_HEAT_CELL_SIZE;
    409
    410    unsigned int sum_framerate = 0;
    411    unsigned int count = 0;
    412
    413    /* Get start of buffer at given coordinates */
    414    const guac_common_surface_heat_cell* heat_row =
    415        surface->heat_map + min_y * heat_width + min_x;
    416
    417    /* Iterate over all the heat map cells for the area
    418     * and calculate the average framerate */
    419    for (y = min_y; y < max_y; y++) {
    420
    421        /* Get current row of heat map */
    422        const guac_common_surface_heat_cell* heat_cell = heat_row;
    423
    424        /* For each cell in subset of row */
    425        for (x = min_x; x < max_x; x++) {
    426
    427            /* Calculate indicies for latest and oldest history entries */
    428            int oldest_entry = heat_cell->oldest_entry;
    429            int latest_entry = oldest_entry - 1;
    430            if (latest_entry < 0)
    431                latest_entry = GUAC_COMMON_SURFACE_HEAT_CELL_HISTORY_SIZE - 1;
    432
    433            /* Calculate elapsed time covering entire history for this cell */
    434            int elapsed_time = heat_cell->history[latest_entry]
    435                             - heat_cell->history[oldest_entry];
    436
    437            /* Calculate and add framerate */
    438            if (elapsed_time)
    439                sum_framerate += GUAC_COMMON_SURFACE_HEAT_CELL_HISTORY_SIZE
    440                    * 1000 / elapsed_time;
    441
    442            /* Next heat map cell */
    443            heat_cell++;
    444            count++;
    445
    446        }
    447
    448        /* Next heat map row */
    449        heat_row += heat_width;
    450
    451    }
    452
    453    /* Calculate the average framerate over entire rect */
    454    if (count)
    455        return sum_framerate / count;
    456
    457    return 0;
    458
    459}
    460
    461 /**
    462 * Guesses whether a rectangle within a particular surface would be better
    463 * compressed as PNG or using a lossy format like JPEG. Positive values
    464 * indicate PNG is likely to be superior, while negative values indicate the
    465 * opposite.
    466 *
    467 * @param surface
    468 *     The surface containing the image data to check.
    469 *
    470 * @param rect
    471 *     The rect to check within the given surface.
    472 *
    473 * @return
    474 *     Positive values if PNG compression is likely to perform better than
    475 *     lossy alternatives, or negative values if PNG is likely to perform
    476 *     worse.
    477 */
    478static int __guac_common_surface_png_optimality(guac_common_surface* surface,
    479        const guac_common_rect* rect) {
    480
    481    int x, y;
    482
    483    int num_same = 0;
    484    int num_different = 1;
    485
    486    /* Get image/buffer metrics */
    487    int width = rect->width;
    488    int height = rect->height;
    489    int stride = surface->stride;
    490
    491    /* Get buffer from surface */
    492    unsigned char* buffer = surface->buffer + rect->y * stride + rect->x * 4;
    493
    494    /* Image must be at least 1x1 */
    495    if (width < 1 || height < 1)
    496        return 0;
    497
    498    /* For each row */
    499    for (y = 0; y < height; y++) {
    500
    501        uint32_t* row = (uint32_t*) buffer;
    502        uint32_t last_pixel = *(row++) | 0xFF000000;
    503
    504        /* For each pixel in current row */
    505        for (x = 1; x < width; x++) {
    506
    507            /* Get next pixel */
    508            uint32_t current_pixel = *(row++) | 0xFF000000;
    509
    510            /* Update same/different counts according to pixel value */
    511            if (current_pixel == last_pixel)
    512                num_same++;
    513            else
    514                num_different++;
    515
    516            last_pixel = current_pixel;
    517
    518        }
    519
    520        /* Advance to next row */
    521        buffer += stride;
    522
    523    }
    524
    525    /* Return rough approximation of optimality for PNG compression */
    526    return 0x100 * num_same / num_different - 0x400;
    527
    528}
    529
    530/**
    531 * Returns whether the given rectangle would be optimally encoded as JPEG
    532 * rather than PNG.
    533 *
    534 * @param surface
    535 *     The surface to be queried.
    536 *
    537 * @param rect
    538 *     The rectangle to check.
    539 *
    540 * @return
    541 *     Non-zero if the rectangle would be optimally encoded as JPEG, zero
    542 *     otherwise.
    543 */
    544static int __guac_common_surface_should_use_jpeg(guac_common_surface* surface,
    545        const guac_common_rect* rect) {
    546
    547    /* Do not use JPEG if lossless quality is required */
    548    if (surface->lossless)
    549        return 0;
    550
    551    /* Calculate the average framerate for the given rect */
    552    int framerate = __guac_common_surface_calculate_framerate(surface, rect);
    553
    554    int rect_size = rect->width * rect->height;
    555
    556    /* JPEG is preferred if:
    557     * - frame rate is high enough
    558     * - image size is large enough
    559     * - PNG is not more optimal based on image contents */
    560    return framerate >= GUAC_COMMON_SURFACE_JPEG_FRAMERATE
    561        && rect_size > GUAC_SURFACE_JPEG_MIN_BITMAP_SIZE
    562        && __guac_common_surface_png_optimality(surface, rect) < 0;
    563
    564}
    565
    566/**
    567 * Returns whether the given rectangle would be optimally encoded as WebP
    568 * rather than PNG.
    569 *
    570 * @param surface
    571 *     The surface to be queried.
    572 *
    573 * @param rect
    574 *     The rectangle to check.
    575 *
    576 * @return
    577 *     Non-zero if the rectangle would be optimally encoded as WebP, zero
    578 *     otherwise.
    579 */
    580static int __guac_common_surface_should_use_webp(guac_common_surface* surface,
    581        const guac_common_rect* rect) {
    582
    583    /* Do not use WebP if not supported */
    584    if (!guac_client_supports_webp(surface->client))
    585        return 0;
    586
    587    /* Calculate the average framerate for the given rect */
    588    int framerate = __guac_common_surface_calculate_framerate(surface, rect);
    589
    590    /* WebP is preferred if:
    591     * - frame rate is high enough
    592     * - PNG is not more optimal based on image contents */
    593    return framerate >= GUAC_COMMON_SURFACE_JPEG_FRAMERATE
    594        && __guac_common_surface_png_optimality(surface, rect) < 0;
    595
    596}
    597
    598/**
    599 * Updates the heat map cells which intersect the given rectangle using the
    600 * given timestamp. This timestamp, along with timestamps from past updates,
    601 * is used to calculate the framerate of each heat cell.
    602 *
    603 * @param surface
    604 *     The surface containing the heat map cells to be updated.
    605 *
    606 * @param rect
    607 *     The rectangle containing the heat map cells to be updated.
    608 *
    609 * @param time
    610 *     The timestamp to use when updating the heat map cells which intersect
    611 *     the given rectangle.
    612 */
    613static void __guac_common_surface_touch_rect(guac_common_surface* surface,
    614        guac_common_rect* rect, guac_timestamp time) {
    615
    616    int x, y;
    617
    618    /* Calculate heat map dimensions */
    619    size_t heat_width = GUAC_COMMON_SURFACE_HEAT_DIMENSION(surface->width);
    620
    621    /* Calculate minimum X/Y coordinates intersecting given rect */
    622    int min_x = rect->x / GUAC_COMMON_SURFACE_HEAT_CELL_SIZE;
    623    int min_y = rect->y / GUAC_COMMON_SURFACE_HEAT_CELL_SIZE;
    624
    625    /* Calculate maximum X/Y coordinates intersecting given rect */
    626    int max_x = min_x + (rect->width  - 1) / GUAC_COMMON_SURFACE_HEAT_CELL_SIZE;
    627    int max_y = min_y + (rect->height - 1) / GUAC_COMMON_SURFACE_HEAT_CELL_SIZE;
    628
    629    /* Get start of buffer at given coordinates */
    630    guac_common_surface_heat_cell* heat_row =
    631        surface->heat_map + min_y * heat_width + min_x;
    632
    633    /* Update all heat map cells which intersect with rectangle */
    634    for (y = min_y; y <= max_y; y++) {
    635
    636        /* Get current row of heat map */
    637        guac_common_surface_heat_cell* heat_cell = heat_row;
    638
    639        /* For each cell in subset of row */
    640        for (x = min_x; x <= max_x; x++) {
    641
    642            /* Replace oldest entry with new timestamp */
    643            heat_cell->history[heat_cell->oldest_entry] = time;
    644
    645            /* Update to next oldest entry */
    646            heat_cell->oldest_entry++;
    647            if (heat_cell->oldest_entry >=
    648                    GUAC_COMMON_SURFACE_HEAT_CELL_HISTORY_SIZE)
    649                heat_cell->oldest_entry = 0;
    650
    651            /* Advance to next heat map cell */
    652            heat_cell++;
    653
    654        }
    655
    656        /* Next heat map row */
    657        heat_row += heat_width;
    658
    659    }
    660
    661}
    662
    663/**
    664 * Flushes the bitmap update currently described by the dirty rectangle within the
    665 * given surface to that surface's bitmap queue. There MUST be space within the
    666 * queue.
    667 *
    668 * @param surface The surface to flush.
    669 */
    670static void __guac_common_surface_flush_to_queue(guac_common_surface* surface) {
    671
    672    guac_common_surface_bitmap_rect* rect;
    673
    674    /* Do not flush if not dirty */
    675    if (!surface->dirty)
    676        return;
    677
    678    /* Add new rect to queue */
    679    rect = &(surface->bitmap_queue[surface->bitmap_queue_length++]);
    680    rect->rect = surface->dirty_rect;
    681    rect->flushed = 0;
    682
    683    /* Surface now flushed */
    684    surface->dirty = 0;
    685
    686}
    687
    688/**
    689 * Flushes the given surface, drawing any pending operations on the remote
    690 * display. Surface properties are not flushed.
    691 *
    692 * @param surface
    693 *     The surface to flush.
    694 */
    695static void __guac_common_surface_flush(guac_common_surface* surface);
    696
    697/**
    698 * Schedules a deferred flush of the given surface. This will not immediately
    699 * flush the surface to the client. Instead, the result of the flush is
    700 * added to a queue which is reinspected and combined (if possible) with other
    701 * deferred flushes during the call to guac_common_surface_flush().
    702 *
    703 * @param surface The surface to flush.
    704 */
    705static void __guac_common_surface_flush_deferred(guac_common_surface* surface) {
    706
    707    /* Do not flush if not dirty */
    708    if (!surface->dirty)
    709        return;
    710
    711    /* Flush if queue size has reached maximum (space is reserved for the final
    712     * dirty rect, as __guac_common_surface_flush() MAY add an additional rect
    713     * to the queue */
    714    if (surface->bitmap_queue_length == GUAC_COMMON_SURFACE_QUEUE_SIZE-1)
    715        __guac_common_surface_flush(surface);
    716
    717    /* Append dirty rect to queue */
    718    __guac_common_surface_flush_to_queue(surface);
    719
    720}
    721
    722/**
    723 * Transfers a single uint32_t using the given transfer function.
    724 *
    725 * @param op The transfer function to use.
    726 * @param src The source of the uint32_t value.
    727 * @param dst THe destination which will hold the result of the transfer.
    728 * @return Non-zero if the destination value was changed, zero otherwise.
    729 */
    730static int __guac_common_surface_transfer_int(guac_transfer_function op, uint32_t* src, uint32_t* dst) {
    731
    732    uint32_t orig = *dst;
    733
    734    switch (op) {
    735
    736        case GUAC_TRANSFER_BINARY_BLACK:
    737            *dst = 0xFF000000;
    738            break;
    739
    740        case GUAC_TRANSFER_BINARY_WHITE:
    741            *dst = 0xFFFFFFFF;
    742            break;
    743
    744        case GUAC_TRANSFER_BINARY_SRC:
    745            *dst = *src;
    746            break;
    747
    748        case GUAC_TRANSFER_BINARY_DEST:
    749            /* NOP */
    750            break;
    751
    752        case GUAC_TRANSFER_BINARY_NSRC:
    753            *dst = *src ^ 0x00FFFFFF;
    754            break;
    755
    756        case GUAC_TRANSFER_BINARY_NDEST:
    757            *dst = *dst ^ 0x00FFFFFF;
    758            break;
    759
    760        case GUAC_TRANSFER_BINARY_AND:
    761            *dst = ((*dst) & (0xFF000000 | *src));
    762            break;
    763
    764        case GUAC_TRANSFER_BINARY_NAND:
    765            *dst = ((*dst) & (0xFF000000 | *src)) ^ 0x00FFFFFF;
    766            break;
    767
    768        case GUAC_TRANSFER_BINARY_OR:
    769            *dst = ((*dst) | (0x00FFFFFF & *src));
    770            break;
    771
    772        case GUAC_TRANSFER_BINARY_NOR:
    773            *dst = ((*dst) | (0x00FFFFFF & *src)) ^ 0x00FFFFFF;
    774            break;
    775
    776        case GUAC_TRANSFER_BINARY_XOR:
    777            *dst = ((*dst) ^ (0x00FFFFFF & *src));
    778            break;
    779
    780        case GUAC_TRANSFER_BINARY_XNOR:
    781            *dst = ((*dst) ^ (0x00FFFFFF & *src)) ^ 0x00FFFFFF;
    782            break;
    783
    784        case GUAC_TRANSFER_BINARY_NSRC_AND:
    785            *dst = ((*dst) & (0xFF000000 | (*src ^ 0x00FFFFFF)));
    786            break;
    787
    788        case GUAC_TRANSFER_BINARY_NSRC_NAND:
    789            *dst = ((*dst) & (0xFF000000 | (*src ^ 0x00FFFFFF))) ^ 0x00FFFFFF;
    790            break;
    791
    792        case GUAC_TRANSFER_BINARY_NSRC_OR:
    793            *dst = ((*dst) | (0x00FFFFFF & (*src ^ 0x00FFFFFF)));
    794            break;
    795
    796        case GUAC_TRANSFER_BINARY_NSRC_NOR:
    797            *dst = ((*dst) | (0x00FFFFFF & (*src ^ 0x00FFFFFF))) ^ 0x00FFFFFF;
    798            break;
    799
    800    }
    801
    802    return *dst != orig;
    803
    804}
    805
    806/**
    807 * Assigns the given value to all pixels within a rectangle of the backing
    808 * surface of the given destination surface. The color of all pixels within the
    809 * rectangle, including the alpha component, is entirely replaced.
    810 *
    811 * @param dst
    812 *     The destination surface.
    813 *
    814 * @param rect
    815 *     The rectangle to draw.
    816 *
    817 * @param red
    818 *     The red component of the color value to assign to all pixels within the
    819 *     rectangle.
    820 *
    821 * @param green
    822 *     The green component of the color value to assign to all pixels within
    823 *     the rectangle.
    824 *
    825 * @param blue 
    826 *     The blue component of the color value to assign to all pixels within the
    827 *     rectangle.
    828 *
    829 * @param alpha 
    830 *     The alpha component of the color value to assign to all pixels within
    831 *     the rectangle.
    832 */
    833static void __guac_common_surface_set(guac_common_surface* dst,
    834        guac_common_rect* rect, int red, int green, int blue, int alpha) {
    835
    836    int x, y;
    837
    838    int dst_stride;
    839    unsigned char* dst_buffer;
    840
    841    uint32_t color = (alpha << 24) | (red << 16) | (green << 8) | blue;
    842
    843    int min_x = rect->width - 1;
    844    int min_y = rect->height - 1;
    845    int max_x = 0;
    846    int max_y = 0;
    847
    848    dst_stride = dst->stride;
    849    dst_buffer = dst->buffer + (dst_stride * rect->y) + (4 * rect->x);
    850
    851    /* For each row */
    852    for (y=0; y < rect->height; y++) {
    853
    854        uint32_t* dst_current = (uint32_t*) dst_buffer;
    855
    856        /* Set row */
    857        for (x=0; x < rect->width; x++) {
    858
    859            uint32_t old_color = *dst_current;
    860
    861            if (old_color != color) {
    862                if (x < min_x) min_x = x;
    863                if (y < min_y) min_y = y;
    864                if (x > max_x) max_x = x;
    865                if (y > max_y) max_y = y;
    866                *dst_current = color;
    867            }
    868
    869            dst_current++;
    870        }
    871
    872        /* Next row */
    873        dst_buffer += dst_stride;
    874
    875    }
    876
    877    /* Restrict destination rect to only updated pixels */
    878    if (max_x >= min_x && max_y >= min_y) {
    879        rect->x += min_x;
    880        rect->y += min_y;
    881        rect->width = max_x - min_x + 1;
    882        rect->height = max_y - min_y + 1;
    883    }
    884    else {
    885        rect->width = 0;
    886        rect->height = 0;
    887    }
    888
    889}
    890
    891/**
    892 * Applies the Porter-Duff "over" composite operator, blending the two given
    893 * color components using the given alpha value.
    894 *
    895 * @param dst
    896 *     The destination color component.
    897 *
    898 * @param src
    899 *     The source color component.
    900 *
    901 * @param alpha
    902 *     The alpha value which applies to the blending operation.
    903 *
    904 * @return
    905 *     The result of applying the Porter-Duff "over" composite operator to the
    906 *     given source and destination components.
    907 */
    908static int guac_common_surface_blend_component(int dst, int src, int alpha) {
    909
    910    int blended = src + dst * (0xFF - alpha);
    911
    912    /* Do not exceed maximum component value */
    913    if (blended > 0xFF)
    914        return 0xFF;
    915
    916    return blended;
    917
    918}
    919
    920/**
    921 * Applies the Porter-Duff "over" composite operator, blending each component
    922 * of the two given ARGB colors.
    923 *
    924 * @param dst
    925 *     The destination ARGB color.
    926 *
    927 * @param src
    928 *     The source ARGB color.
    929 *
    930 * @return
    931 *     The result of applying the Porter-Duff "over" composite operator to the
    932 *     given source and destination colors.
    933 */
    934static uint32_t guac_common_surface_argb_blend(uint32_t dst, uint32_t src) {
    935
    936    /* Separate destination ARGB color into its components */
    937    int dst_a = (dst >> 24) & 0xFF;
    938    int dst_r = (dst >> 16) & 0xFF;
    939    int dst_g = (dst >>  8) & 0xFF;
    940    int dst_b =  dst        & 0xFF;
    941
    942    /* Separate source ARGB color into its components */
    943    int src_a = (src >> 24) & 0xFF;
    944    int src_r = (src >> 16) & 0xFF;
    945    int src_g = (src >>  8) & 0xFF;
    946    int src_b =  src        & 0xFF;
    947
    948    /* If source is fully opaque (or destination is fully transparent), the
    949     * blended result is the source */
    950    if (src_a == 0xFF || dst_a == 0x00)
    951        return src;
    952
    953    /* If source is fully transparent, the blended result is the destination */
    954    if (src_a == 0x00)
    955        return dst;
    956
    957    /* Otherwise, blend each ARGB component, assuming pre-multiplied alpha */
    958    int r = guac_common_surface_blend_component(dst_r, src_r, src_a);
    959    int g = guac_common_surface_blend_component(dst_g, src_g, src_a);
    960    int b = guac_common_surface_blend_component(dst_b, src_b, src_a);
    961    int a = guac_common_surface_blend_component(dst_a, src_a, src_a);
    962
    963    /* Recombine blended components */
    964    return (a << 24) | (r << 16) | (g << 8) | b;
    965
    966}
    967
    968/**
    969 * Copies data from the given buffer to the surface at the given coordinates.
    970 * The dimensions and location of the destination rectangle will be altered
    971 * to remove as many unchanged pixels as possible.
    972 *
    973 * @param src_buffer The buffer to copy.
    974 * @param src_stride The number of bytes in each row of the source buffer.
    975 * @param sx The X coordinate of the source rectangle.
    976 * @param sy The Y coordinate of the source rectangle.
    977 * @param dst The destination surface.
    978 * @param rect The destination rectangle.
    979 * @param opaque Non-zero if the source surface is opaque (its alpha channel
    980 *               should be ignored), zero otherwise.
    981 */
    982static void __guac_common_surface_put(unsigned char* src_buffer, int src_stride,
    983                                      int* sx, int* sy,
    984                                      guac_common_surface* dst, guac_common_rect* rect,
    985                                      int opaque) {
    986
    987    unsigned char* dst_buffer = dst->buffer;
    988    int dst_stride = dst->stride;
    989
    990    int x, y;
    991
    992    int min_x = rect->width;
    993    int min_y = rect->height;
    994    int max_x = 0;
    995    int max_y = 0;
    996
    997    int orig_x = rect->x;
    998    int orig_y = rect->y;
    999
   1000    src_buffer += src_stride * (*sy) + 4 * (*sx);
   1001    dst_buffer += (dst_stride * rect->y) + (4 * rect->x);
   1002
   1003    /* For each row */
   1004    for (y=0; y < rect->height; y++) {
   1005
   1006        uint32_t* src_current = (uint32_t*) src_buffer;
   1007        uint32_t* dst_current = (uint32_t*) dst_buffer;
   1008
   1009        /* Copy row */
   1010        for (x=0; x < rect->width; x++) {
   1011
   1012            uint32_t color;
   1013
   1014            /* Get source and destination color values */
   1015            uint32_t src_color = *src_current;
   1016            uint32_t dst_color = *dst_current;
   1017
   1018            /* Ignore alpha channel if opaque */
   1019            if (opaque)
   1020                color = src_color | 0xFF000000;
   1021
   1022            /* Otherwise, perform alpha blending operation */
   1023            else
   1024                color = guac_common_surface_argb_blend(dst_color, src_color);
   1025
   1026            /* If the destination color is changing, update rectangle bounds
   1027             * and store the new color */
   1028            if (dst_color != color) {
   1029                if (x < min_x) min_x = x;
   1030                if (y < min_y) min_y = y;
   1031                if (x > max_x) max_x = x;
   1032                if (y > max_y) max_y = y;
   1033                *dst_current = color;
   1034            }
   1035
   1036            /* Advance to next pixel */
   1037            src_current++;
   1038            dst_current++;
   1039
   1040        }
   1041
   1042        /* Next row */
   1043        src_buffer += src_stride;
   1044        dst_buffer += dst_stride;
   1045
   1046    }
   1047
   1048    /* Restrict destination rect to only updated pixels */
   1049    if (max_x >= min_x && max_y >= min_y) {
   1050        rect->x += min_x;
   1051        rect->y += min_y;
   1052        rect->width = max_x - min_x + 1;
   1053        rect->height = max_y - min_y + 1;
   1054    }
   1055    else {
   1056        rect->width = 0;
   1057        rect->height = 0;
   1058    }
   1059
   1060    /* Update source X/Y */
   1061    *sx += rect->x - orig_x;
   1062    *sy += rect->y - orig_y;
   1063
   1064}
   1065
   1066/**
   1067 * Fills the given surface with color, using the given buffer as a mask. Color
   1068 * will be added to the given surface iff the corresponding pixel within the
   1069 * buffer is opaque.
   1070 *
   1071 * @param src_buffer The buffer to use as a mask.
   1072 * @param src_stride The number of bytes in each row of the source buffer.
   1073 * @param sx The X coordinate of the source rectangle.
   1074 * @param sy The Y coordinate of the source rectangle.
   1075 * @param dst The destination surface.
   1076 * @param rect The destination rectangle.
   1077 * @param red The red component of the color of the fill.
   1078 * @param green The green component of the color of the fill.
   1079 * @param blue The blue component of the color of the fill.
   1080 */
   1081static void __guac_common_surface_fill_mask(unsigned char* src_buffer, int src_stride,
   1082                                            int sx, int sy,
   1083                                            guac_common_surface* dst, guac_common_rect* rect,
   1084                                            int red, int green, int blue) {
   1085
   1086    unsigned char* dst_buffer = dst->buffer;
   1087    int dst_stride = dst->stride;
   1088
   1089    uint32_t color = 0xFF000000 | (red << 16) | (green << 8) | blue;
   1090    int x, y;
   1091
   1092    src_buffer += src_stride*sy + 4*sx;
   1093    dst_buffer += (dst_stride * rect->y) + (4 * rect->x);
   1094
   1095    /* For each row */
   1096    for (y=0; y < rect->height; y++) {
   1097
   1098        uint32_t* src_current = (uint32_t*) src_buffer;
   1099        uint32_t* dst_current = (uint32_t*) dst_buffer;
   1100
   1101        /* Stencil row */
   1102        for (x=0; x < rect->width; x++) {
   1103
   1104            /* Fill with color if opaque */
   1105            if (*src_current & 0xFF000000)
   1106                *dst_current = color;
   1107
   1108            src_current++;
   1109            dst_current++;
   1110        }
   1111
   1112        /* Next row */
   1113        src_buffer += src_stride;
   1114        dst_buffer += dst_stride;
   1115
   1116    }
   1117
   1118}
   1119
   1120/**
   1121 * Copies data from the given surface to the given destination surface using
   1122 * the specified transfer function.
   1123 *
   1124 * @param src_buffer The buffer to copy.
   1125 * @param src_stride The number of bytes in each row of the source buffer.
   1126 * @param sx The X coordinate of the source rectangle.
   1127 * @param sy The Y coordinate of the source rectangle.
   1128 * @param op The transfer function to use.
   1129 * @param dst The destination surface.
   1130 * @param rect The destination rectangle.
   1131 */
   1132static void __guac_common_surface_transfer(guac_common_surface* src, int* sx, int* sy,
   1133                                           guac_transfer_function op,
   1134                                           guac_common_surface* dst, guac_common_rect* rect) {
   1135
   1136    unsigned char* src_buffer = src->buffer;
   1137    unsigned char* dst_buffer = dst->buffer;
   1138
   1139    int x, y;
   1140    int src_stride, dst_stride;
   1141    int step = 1;
   1142
   1143    int min_x = rect->width - 1;
   1144    int min_y = rect->height - 1;
   1145    int max_x = 0;
   1146    int max_y = 0;
   1147
   1148    int orig_x = rect->x;
   1149    int orig_y = rect->y;
   1150
   1151    /* Copy forwards only if destination is in a different surface or is before source */
   1152    if (src != dst || rect->y < *sy || (rect->y == *sy && rect->x < *sx)) {
   1153        src_buffer += src->stride * (*sy) + 4 * (*sx);
   1154        dst_buffer += (dst->stride * rect->y) + (4 * rect->x);
   1155        src_stride = src->stride;
   1156        dst_stride = dst->stride;
   1157        step = 1;
   1158    }
   1159
   1160    /* Otherwise, copy backwards */
   1161    else {
   1162        src_buffer += src->stride * (*sy + rect->height - 1) + 4 * (*sx + rect->width - 1);
   1163        dst_buffer += dst->stride * (rect->y + rect->height - 1) + 4 * (rect->x + rect->width - 1);
   1164        src_stride = -src->stride;
   1165        dst_stride = -dst->stride;
   1166        step = -1;
   1167    }
   1168
   1169    /* For each row */
   1170    for (y=0; y < rect->height; y++) {
   1171
   1172        uint32_t* src_current = (uint32_t*) src_buffer;
   1173        uint32_t* dst_current = (uint32_t*) dst_buffer;
   1174
   1175        /* Transfer each pixel in row */
   1176        for (x=0; x < rect->width; x++) {
   1177
   1178            if (__guac_common_surface_transfer_int(op, src_current, dst_current)) {
   1179                if (x < min_x) min_x = x;
   1180                if (y < min_y) min_y = y;
   1181                if (x > max_x) max_x = x;
   1182                if (y > max_y) max_y = y;
   1183            }
   1184
   1185            src_current += step;
   1186            dst_current += step;
   1187        }
   1188
   1189        /* Next row */
   1190        src_buffer += src_stride;
   1191        dst_buffer += dst_stride;
   1192
   1193    }
   1194
   1195    /* Translate X coordinate space of moving backwards */
   1196    if (step < 0) {
   1197        int old_max_x = max_x;
   1198        max_x = rect->width - 1 - min_x;
   1199        min_x = rect->width - 1 - old_max_x;
   1200    }
   1201
   1202    /* Translate Y coordinate space of moving backwards */
   1203    if (dst_stride < 0) {
   1204        int old_max_y = max_y;
   1205        max_y = rect->height - 1 - min_y;
   1206        min_y = rect->height - 1 - old_max_y;
   1207    }
   1208
   1209    /* Restrict destination rect to only updated pixels */
   1210    if (max_x >= min_x && max_y >= min_y) {
   1211        rect->x += min_x;
   1212        rect->y += min_y;
   1213        rect->width = max_x - min_x + 1;
   1214        rect->height = max_y - min_y + 1;
   1215    }
   1216    else {
   1217        rect->width = 0;
   1218        rect->height = 0;
   1219    }
   1220
   1221    /* Update source X/Y */
   1222    *sx += rect->x - orig_x;
   1223    *sy += rect->y - orig_y;
   1224
   1225}
   1226
   1227guac_common_surface* guac_common_surface_alloc(guac_client* client,
   1228        guac_socket* socket, const guac_layer* layer, int w, int h) {
   1229
   1230    /* Calculate heat map dimensions */
   1231    size_t heat_width = GUAC_COMMON_SURFACE_HEAT_DIMENSION(w);
   1232    size_t heat_height = GUAC_COMMON_SURFACE_HEAT_DIMENSION(h);
   1233
   1234    /* Init surface */
   1235    guac_common_surface* surface = guac_mem_zalloc(sizeof(guac_common_surface));
   1236    surface->client = client;
   1237    surface->socket = socket;
   1238    surface->layer = layer;
   1239    surface->parent = GUAC_DEFAULT_LAYER;
   1240    surface->opacity = 0xFF;
   1241    surface->width = w;
   1242    surface->height = h;
   1243
   1244    pthread_mutex_init(&surface->_lock, NULL);
   1245
   1246    /* Create corresponding Cairo surface */
   1247    surface->stride = cairo_format_stride_for_width(CAIRO_FORMAT_ARGB32, w);
   1248    surface->buffer = guac_mem_zalloc(h, surface->stride);
   1249
   1250    /* Create corresponding heat map */
   1251    surface->heat_map = guac_mem_zalloc(heat_width, heat_height,
   1252            sizeof(guac_common_surface_heat_cell));
   1253
   1254    /* Reset clipping rect */
   1255    guac_common_surface_reset_clip(surface);
   1256
   1257    /* Layers must initially exist */
   1258    if (layer->index >= 0) {
   1259        guac_protocol_send_size(socket, layer, w, h);
   1260        surface->realized = 1;
   1261    }
   1262
   1263    /* Defer creation of buffers */
   1264    else
   1265        surface->realized = 0;
   1266
   1267    return surface;
   1268}
   1269
   1270void guac_common_surface_free(guac_common_surface* surface) {
   1271
   1272    /* Only dispose of surface if it exists */
   1273    if (surface->realized)
   1274        guac_protocol_send_dispose(surface->socket, surface->layer);
   1275
   1276    pthread_mutex_destroy(&surface->_lock);
   1277
   1278    guac_mem_free(surface->heat_map);
   1279    guac_mem_free(surface->buffer);
   1280    guac_mem_free(surface);
   1281
   1282}
   1283
   1284void guac_common_surface_resize(guac_common_surface* surface, int w, int h) {
   1285
   1286    pthread_mutex_lock(&surface->_lock);
   1287
   1288    /* Ignore if resize will have no effect */
   1289    if (w == surface->width && h == surface->height)
   1290        goto complete;
   1291
   1292    guac_socket* socket = surface->socket;
   1293    const guac_layer* layer = surface->layer;
   1294
   1295    unsigned char* old_buffer;
   1296    int old_stride;
   1297    guac_common_rect old_rect;
   1298
   1299    int sx = 0;
   1300    int sy = 0;
   1301
   1302    /* Calculate heat map dimensions */
   1303    size_t heat_width = GUAC_COMMON_SURFACE_HEAT_DIMENSION(w);
   1304    size_t heat_height = GUAC_COMMON_SURFACE_HEAT_DIMENSION(h);
   1305
   1306    /* Copy old surface data */
   1307    old_buffer = surface->buffer;
   1308    old_stride = surface->stride;
   1309    guac_common_rect_init(&old_rect, 0, 0, surface->width, surface->height);
   1310
   1311    /* Re-initialize at new size */
   1312    surface->width  = w;
   1313    surface->height = h;
   1314    surface->stride = cairo_format_stride_for_width(CAIRO_FORMAT_ARGB32, w);
   1315    surface->buffer = guac_mem_zalloc(h, surface->stride);
   1316    __guac_common_bound_rect(surface, &surface->clip_rect, NULL, NULL);
   1317
   1318    /* Copy relevant old data */
   1319    __guac_common_bound_rect(surface, &old_rect, NULL, NULL);
   1320    __guac_common_surface_put(old_buffer, old_stride, &sx, &sy, surface, &old_rect, 1);
   1321
   1322    /* Free old data */
   1323    guac_mem_free(old_buffer);
   1324
   1325    /* Allocate completely new heat map (can safely discard old stats) */
   1326    guac_mem_free(surface->heat_map);
   1327    surface->heat_map = guac_mem_alloc(heat_width, heat_height,
   1328            sizeof(guac_common_surface_heat_cell));
   1329
   1330    /* Resize dirty rect to fit new surface dimensions */
   1331    if (surface->dirty) {
   1332        __guac_common_bound_rect(surface, &surface->dirty_rect, NULL, NULL);
   1333        if (surface->dirty_rect.width <= 0 || surface->dirty_rect.height <= 0)
   1334            surface->dirty = 0;
   1335    }
   1336
   1337    /* Update Guacamole layer */
   1338    if (surface->realized)
   1339        guac_protocol_send_size(socket, layer, w, h);
   1340
   1341complete:
   1342    pthread_mutex_unlock(&surface->_lock);
   1343
   1344}
   1345
   1346void guac_common_surface_draw(guac_common_surface* surface, int x, int y, cairo_surface_t* src) {
   1347
   1348    pthread_mutex_lock(&surface->_lock);
   1349
   1350    unsigned char* buffer = cairo_image_surface_get_data(src);
   1351    cairo_format_t format = cairo_image_surface_get_format(src);
   1352    int stride = cairo_image_surface_get_stride(src);
   1353    int w = cairo_image_surface_get_width(src);
   1354    int h = cairo_image_surface_get_height(src);
   1355
   1356    int sx = 0;
   1357    int sy = 0;
   1358
   1359    guac_common_rect rect;
   1360    guac_common_rect_init(&rect, x, y, w, h);
   1361
   1362    /* Clip operation */
   1363    __guac_common_clip_rect(surface, &rect, &sx, &sy);
   1364    if (rect.width <= 0 || rect.height <= 0)
   1365        goto complete;
   1366
   1367    /* Update backing surface */
   1368    __guac_common_surface_put(buffer, stride, &sx, &sy, surface, &rect, format != CAIRO_FORMAT_ARGB32);
   1369    if (rect.width <= 0 || rect.height <= 0)
   1370        goto complete;
   1371
   1372    /* Update the heat map for the update rectangle. */
   1373    guac_timestamp time = guac_timestamp_current();
   1374    __guac_common_surface_touch_rect(surface, &rect, time);
   1375
   1376    /* Flush if not combining */
   1377    if (!__guac_common_should_combine(surface, &rect, 0))
   1378        __guac_common_surface_flush_deferred(surface);
   1379
   1380    /* Always defer draws */
   1381    __guac_common_mark_dirty(surface, &rect);
   1382
   1383complete:
   1384    pthread_mutex_unlock(&surface->_lock);
   1385
   1386}
   1387
   1388void guac_common_surface_paint(guac_common_surface* surface, int x, int y,
   1389        cairo_surface_t* src, int red, int green, int blue) {
   1390
   1391    pthread_mutex_lock(&surface->_lock);
   1392
   1393    unsigned char* buffer = cairo_image_surface_get_data(src);
   1394    int stride = cairo_image_surface_get_stride(src);
   1395    int w = cairo_image_surface_get_width(src);
   1396    int h = cairo_image_surface_get_height(src);
   1397
   1398    int sx = 0;
   1399    int sy = 0;
   1400
   1401    guac_common_rect rect;
   1402    guac_common_rect_init(&rect, x, y, w, h);
   1403
   1404    /* Clip operation */
   1405    __guac_common_clip_rect(surface, &rect, &sx, &sy);
   1406    if (rect.width <= 0 || rect.height <= 0)
   1407        goto complete;
   1408
   1409    /* Update backing surface */
   1410    __guac_common_surface_fill_mask(buffer, stride, sx, sy, surface, &rect, red, green, blue);
   1411
   1412    /* Flush if not combining */
   1413    if (!__guac_common_should_combine(surface, &rect, 0))
   1414        __guac_common_surface_flush_deferred(surface);
   1415
   1416    /* Always defer draws */
   1417    __guac_common_mark_dirty(surface, &rect);
   1418
   1419complete:
   1420    pthread_mutex_unlock(&surface->_lock);
   1421
   1422}
   1423
   1424void guac_common_surface_copy(guac_common_surface* src, int sx, int sy,
   1425        int w, int h, guac_common_surface* dst, int dx, int dy) {
   1426
   1427    /* Lock both surfaces */
   1428    pthread_mutex_lock(&dst->_lock);
   1429    if (src != dst)
   1430        pthread_mutex_lock(&src->_lock);
   1431
   1432    guac_socket* socket = dst->socket;
   1433    const guac_layer* src_layer = src->layer;
   1434    const guac_layer* dst_layer = dst->layer;
   1435
   1436    guac_common_rect srect;
   1437    guac_common_rect_init(&srect, sx, sy, w, h);
   1438
   1439    /* Clip operation source rect to bounds */
   1440    __guac_common_bound_rect(src, &srect, &dx, &dy);
   1441    if (srect.width <= 0 || srect.height <= 0)
   1442        goto complete;
   1443
   1444    guac_common_rect drect;
   1445    guac_common_rect_init(&drect, dx, dy,
   1446            srect.width, srect.height);
   1447
   1448    /* Clip operation destination rect */
   1449    __guac_common_clip_rect(dst, &drect, &srect.x, &srect.y);
   1450    if (drect.width <= 0 || drect.height <= 0)
   1451        goto complete;
   1452
   1453    /* NOTE: Being the last rectangle to be adjusted, only the width/height of
   1454     * drect is now correct! */
   1455
   1456    /* Update backing surface first only if drect cannot intersect srect */
   1457    if (src != dst) {
   1458        __guac_common_surface_transfer(src, &srect.x, &srect.y,
   1459                GUAC_TRANSFER_BINARY_SRC, dst, &drect);
   1460        if (drect.width <= 0 || drect.height <= 0)
   1461            goto complete;
   1462    }
   1463
   1464    /* Defer if combining */
   1465    if (__guac_common_should_combine(dst, &drect, 1))
   1466        __guac_common_mark_dirty(dst, &drect);
   1467
   1468    /* Otherwise, flush and draw immediately */
   1469    else {
   1470        __guac_common_surface_flush(dst);
   1471        __guac_common_surface_flush(src);
   1472        guac_protocol_send_copy(socket, src_layer, srect.x, srect.y,
   1473                drect.width, drect.height, GUAC_COMP_OVER, dst_layer,
   1474                drect.x, drect.y);
   1475        dst->realized = 1;
   1476    }
   1477
   1478    /* Update backing surface last if drect can intersect srect */
   1479    if (src == dst)
   1480        __guac_common_surface_transfer(src, &srect.x, &srect.y,
   1481                GUAC_TRANSFER_BINARY_SRC, dst, &drect);
   1482
   1483complete:
   1484
   1485    /* Unlock both surfaces */
   1486    pthread_mutex_unlock(&dst->_lock);
   1487    if (src != dst)
   1488        pthread_mutex_unlock(&src->_lock);
   1489
   1490}
   1491
   1492void guac_common_surface_transfer(guac_common_surface* src, int sx, int sy, int w, int h,
   1493                                  guac_transfer_function op, guac_common_surface* dst, int dx, int dy) {
   1494
   1495    /* Lock both surfaces */
   1496    pthread_mutex_lock(&dst->_lock);
   1497    if (src != dst)
   1498        pthread_mutex_lock(&src->_lock);
   1499
   1500    guac_socket* socket = dst->socket;
   1501    const guac_layer* src_layer = src->layer;
   1502    const guac_layer* dst_layer = dst->layer;
   1503
   1504    guac_common_rect srect;
   1505    guac_common_rect_init(&srect, sx, sy, w, h);
   1506
   1507    /* Clip operation source rect to bounds */
   1508    __guac_common_bound_rect(src, &srect, &dx, &dy);
   1509    if (srect.width <= 0 || srect.height <= 0)
   1510        goto complete;
   1511
   1512    guac_common_rect drect;
   1513    guac_common_rect_init(&drect, dx, dy,
   1514            srect.width, srect.height);
   1515
   1516    /* Clip operation destination rect */
   1517    __guac_common_clip_rect(dst, &drect, &srect.x, &srect.y);
   1518    if (drect.width <= 0 || drect.height <= 0)
   1519        goto complete;
   1520
   1521    /* NOTE: Being the last rectangle to be adjusted, only the width/height of
   1522     * drect is now correct! */
   1523
   1524    /* Update backing surface first only if drect cannot intersect srect */
   1525    if (src != dst) {
   1526        __guac_common_surface_transfer(src, &srect.x, &srect.y, op, dst, &drect);
   1527        if (drect.width <= 0 || drect.height <= 0)
   1528            goto complete;
   1529    }
   1530
   1531    /* Defer if combining */
   1532    if (__guac_common_should_combine(dst, &drect, 1))
   1533        __guac_common_mark_dirty(dst, &drect);
   1534
   1535    /* Otherwise, flush and draw immediately */
   1536    else {
   1537        __guac_common_surface_flush(dst);
   1538        __guac_common_surface_flush(src);
   1539        guac_protocol_send_transfer(socket, src_layer, srect.x, srect.y,
   1540                drect.width, drect.height, op, dst_layer, drect.x, drect.y);
   1541        dst->realized = 1;
   1542    }
   1543
   1544    /* Update backing surface last if drect can intersect srect */
   1545    if (src == dst)
   1546        __guac_common_surface_transfer(src, &srect.x, &srect.y, op, dst, &drect);
   1547
   1548complete:
   1549
   1550    /* Unlock both surfaces */
   1551    pthread_mutex_unlock(&dst->_lock);
   1552    if (src != dst)
   1553        pthread_mutex_unlock(&src->_lock);
   1554
   1555}
   1556
   1557void guac_common_surface_set(guac_common_surface* surface,
   1558        int x, int y, int w, int h, int red, int green, int blue, int alpha) {
   1559
   1560    pthread_mutex_lock(&surface->_lock);
   1561
   1562    guac_socket* socket = surface->socket;
   1563    const guac_layer* layer = surface->layer;
   1564
   1565    guac_common_rect rect;
   1566    guac_common_rect_init(&rect, x, y, w, h);
   1567
   1568    /* Clip operation */
   1569    __guac_common_clip_rect(surface, &rect, NULL, NULL);
   1570    if (rect.width <= 0 || rect.height <= 0)
   1571        goto complete;
   1572
   1573    /* Update backing surface */
   1574    __guac_common_surface_set(surface, &rect, red, green, blue, alpha);
   1575    if (rect.width <= 0 || rect.height <= 0)
   1576        goto complete;
   1577
   1578    /* Handle as normal draw if non-opaque */
   1579    if (alpha != 0xFF) {
   1580
   1581        /* Flush if not combining */
   1582        if (!__guac_common_should_combine(surface, &rect, 0))
   1583            __guac_common_surface_flush_deferred(surface);
   1584
   1585        /* Always defer draws */
   1586        __guac_common_mark_dirty(surface, &rect);
   1587
   1588    }
   1589
   1590    /* Defer if combining */
   1591    else if (__guac_common_should_combine(surface, &rect, 1))
   1592        __guac_common_mark_dirty(surface, &rect);
   1593
   1594    /* Otherwise, flush and draw immediately */
   1595    else {
   1596        __guac_common_surface_flush(surface);
   1597        guac_protocol_send_rect(socket, layer, rect.x, rect.y, rect.width, rect.height);
   1598        guac_protocol_send_cfill(socket, GUAC_COMP_OVER, layer, red, green, blue, alpha);
   1599        surface->realized = 1;
   1600    }
   1601
   1602complete:
   1603    pthread_mutex_unlock(&surface->_lock);
   1604
   1605}
   1606
   1607void guac_common_surface_clip(guac_common_surface* surface, int x, int y, int w, int h) {
   1608
   1609    pthread_mutex_lock(&surface->_lock);
   1610
   1611    guac_common_rect clip;
   1612
   1613    /* Init clipping rectangle if clipping not already applied */
   1614    if (!surface->clipped) {
   1615        guac_common_rect_init(&surface->clip_rect, 0, 0, surface->width, surface->height);
   1616        surface->clipped = 1;
   1617    }
   1618
   1619    guac_common_rect_init(&clip, x, y, w, h);
   1620    guac_common_rect_constrain(&surface->clip_rect, &clip);
   1621
   1622    pthread_mutex_unlock(&surface->_lock);
   1623
   1624}
   1625
   1626void guac_common_surface_reset_clip(guac_common_surface* surface) {
   1627    pthread_mutex_lock(&surface->_lock);
   1628    surface->clipped = 0;
   1629    pthread_mutex_unlock(&surface->_lock);
   1630}
   1631
   1632/**
   1633 * Flushes the bitmap update currently described by the dirty rectangle within
   1634 * the given surface directly via an "img" instruction as PNG data. The
   1635 * resulting instructions will be sent over the socket associated with the
   1636 * given surface.
   1637 *
   1638 * @param surface
   1639 *     The surface to flush.
   1640 *
   1641 * @param opaque
   1642 *     Whether the rectangle being flushed contains only fully-opaque pixels.
   1643 */
   1644static void __guac_common_surface_flush_to_png(guac_common_surface* surface,
   1645        int opaque) {
   1646
   1647    if (surface->dirty) {
   1648
   1649        guac_socket* socket = surface->socket;
   1650        const guac_layer* layer = surface->layer;
   1651
   1652        /* Get Cairo surface for specified rect */
   1653        unsigned char* buffer = surface->buffer
   1654                              + surface->dirty_rect.y * surface->stride
   1655                              + surface->dirty_rect.x * 4;
   1656
   1657        cairo_surface_t* rect;
   1658
   1659        /* Use RGB24 if the image is fully opaque */
   1660        if (opaque)
   1661            rect = cairo_image_surface_create_for_data(buffer,
   1662                    CAIRO_FORMAT_RGB24, surface->dirty_rect.width,
   1663                    surface->dirty_rect.height, surface->stride);
   1664
   1665        /* Otherwise ARGB32 is needed */
   1666        else {
   1667
   1668            rect = cairo_image_surface_create_for_data(buffer,
   1669                    CAIRO_FORMAT_ARGB32, surface->dirty_rect.width,
   1670                    surface->dirty_rect.height, surface->stride);
   1671
   1672            /* Clear destination rect first */
   1673            guac_protocol_send_rect(socket, layer,
   1674                    surface->dirty_rect.x, surface->dirty_rect.y,
   1675                    surface->dirty_rect.width, surface->dirty_rect.height);
   1676            guac_protocol_send_cfill(socket, GUAC_COMP_ROUT, layer,
   1677                    0x00, 0x00, 0x00, 0xFF);
   1678
   1679        }
   1680
   1681        /* Send PNG for rect */
   1682        guac_client_stream_png(surface->client, socket, GUAC_COMP_OVER,
   1683                layer, surface->dirty_rect.x, surface->dirty_rect.y, rect);
   1684
   1685        cairo_surface_destroy(rect);
   1686        surface->realized = 1;
   1687
   1688        /* Surface is no longer dirty */
   1689        surface->dirty = 0;
   1690
   1691    }
   1692
   1693}
   1694
   1695/**
   1696 * Returns an appropriate quality between 0 and 100 for lossy encoding
   1697 * depending on the current processing lag calculated for the given client.
   1698 *
   1699 * @param client
   1700 *     The client for which the lossy quality is being calculated.
   1701 *
   1702 * @return
   1703 *     A value between 0 and 100 inclusive which seems appropriate for the
   1704 *     client based on lag measurements.
   1705 */
   1706static int guac_common_surface_suggest_quality(guac_client* client) {
   1707
   1708    int lag = guac_client_get_processing_lag(client);
   1709
   1710    /* Scale quality linearly from 90 to 30 as lag varies from 20ms to 80ms */
   1711    int quality = 90 - (lag - 20);
   1712
   1713    /* Do not exceed 90 for quality */
   1714    if (quality > 90)
   1715        return 90;
   1716
   1717    /* Do not go below 30 for quality */
   1718    if (quality < 30)
   1719        return 30;
   1720
   1721    return quality;
   1722
   1723}
   1724
   1725/**
   1726 * Flushes the bitmap update currently described by the dirty rectangle within
   1727 * the given surface directly via an "img" instruction as JPEG data. The
   1728 * resulting instructions will be sent over the socket associated with the
   1729 * given surface.
   1730 *
   1731 * @param surface
   1732 *     The surface to flush.
   1733 */
   1734static void __guac_common_surface_flush_to_jpeg(guac_common_surface* surface) {
   1735
   1736    if (surface->dirty) {
   1737
   1738        guac_socket* socket = surface->socket;
   1739        const guac_layer* layer = surface->layer;
   1740
   1741        guac_common_rect max;
   1742        guac_common_rect_init(&max, 0, 0, surface->width, surface->height);
   1743
   1744        /* Expand the dirty rect size to fit in a grid with cells equal to the
   1745         * minimum JPEG block size */
   1746        guac_common_rect_expand_to_grid(GUAC_SURFACE_JPEG_BLOCK_SIZE,
   1747                                        &surface->dirty_rect, &max);
   1748
   1749        /* Get Cairo surface for specified rect */
   1750        unsigned char* buffer = surface->buffer
   1751                              + surface->dirty_rect.y * surface->stride
   1752                              + surface->dirty_rect.x * 4;
   1753
   1754        cairo_surface_t* rect = cairo_image_surface_create_for_data(buffer,
   1755                CAIRO_FORMAT_RGB24, surface->dirty_rect.width,
   1756                surface->dirty_rect.height, surface->stride);
   1757
   1758        /* Send JPEG for rect */
   1759        guac_client_stream_jpeg(surface->client, socket, GUAC_COMP_OVER, layer,
   1760                surface->dirty_rect.x, surface->dirty_rect.y, rect,
   1761                guac_common_surface_suggest_quality(surface->client));
   1762
   1763        cairo_surface_destroy(rect);
   1764        surface->realized = 1;
   1765
   1766        /* Surface is no longer dirty */
   1767        surface->dirty = 0;
   1768
   1769    }
   1770
   1771}
   1772
   1773/**
   1774 * Flushes the bitmap update currently described by the dirty rectangle within
   1775 * the given surface directly via an "img" instruction as WebP data. The
   1776 * resulting instructions will be sent over the socket associated with the
   1777 * given surface.
   1778 *
   1779 * @param surface
   1780 *     The surface to flush.
   1781 *
   1782 * @param opaque
   1783 *     Whether the rectangle being flushed contains only fully-opaque pixels.
   1784 */
   1785static void __guac_common_surface_flush_to_webp(guac_common_surface* surface,
   1786        int opaque) {
   1787
   1788    if (surface->dirty) {
   1789
   1790        guac_socket* socket = surface->socket;
   1791        const guac_layer* layer = surface->layer;
   1792
   1793        guac_common_rect max;
   1794        guac_common_rect_init(&max, 0, 0, surface->width, surface->height);
   1795
   1796        /* Expand the dirty rect size to fit in a grid with cells equal to the
   1797         * minimum WebP block size */
   1798        guac_common_rect_expand_to_grid(GUAC_SURFACE_WEBP_BLOCK_SIZE,
   1799                                        &surface->dirty_rect, &max);
   1800
   1801        /* Get Cairo surface for specified rect */
   1802        unsigned char* buffer = surface->buffer
   1803                              + surface->dirty_rect.y * surface->stride
   1804                              + surface->dirty_rect.x * 4;
   1805
   1806        cairo_surface_t* rect;
   1807
   1808        /* Use RGB24 if the image is fully opaque */
   1809        if (opaque)
   1810            rect = cairo_image_surface_create_for_data(buffer,
   1811                    CAIRO_FORMAT_RGB24, surface->dirty_rect.width,
   1812                    surface->dirty_rect.height, surface->stride);
   1813
   1814        /* Otherwise ARGB32 is needed */
   1815        else
   1816            rect = cairo_image_surface_create_for_data(buffer,
   1817                    CAIRO_FORMAT_ARGB32, surface->dirty_rect.width,
   1818                    surface->dirty_rect.height, surface->stride);
   1819
   1820        /* Send WebP for rect */
   1821        guac_client_stream_webp(surface->client, socket, GUAC_COMP_OVER, layer,
   1822                surface->dirty_rect.x, surface->dirty_rect.y, rect,
   1823                guac_common_surface_suggest_quality(surface->client),
   1824                surface->lossless ? 1 : 0);
   1825
   1826        cairo_surface_destroy(rect);
   1827        surface->realized = 1;
   1828
   1829        /* Surface is no longer dirty */
   1830        surface->dirty = 0;
   1831
   1832    }
   1833
   1834}
   1835
   1836/**
   1837 * Comparator for instances of guac_common_surface_bitmap_rect, the elements
   1838 * which make up a surface's bitmap buffer.
   1839 *
   1840 * @see qsort
   1841 */
   1842static int __guac_common_surface_bitmap_rect_compare(const void* a, const void* b) {
   1843
   1844    guac_common_surface_bitmap_rect* ra = (guac_common_surface_bitmap_rect*) a;
   1845    guac_common_surface_bitmap_rect* rb = (guac_common_surface_bitmap_rect*) b;
   1846
   1847    /* Order roughly top to bottom, left to right */
   1848    if (ra->rect.y != rb->rect.y) return ra->rect.y - rb->rect.y;
   1849    if (ra->rect.x != rb->rect.x) return ra->rect.x - rb->rect.x;
   1850
   1851    /* Wider updates should come first (more likely to intersect later) */
   1852    if (ra->rect.width != rb->rect.width) return rb->rect.width - ra->rect.width;
   1853
   1854    /* Shorter updates should come first (less likely to increase cost) */
   1855    return ra->rect.height - rb->rect.height;
   1856
   1857}
   1858
   1859/**
   1860 * Flushes only the properties of the given surface, such as layer location or
   1861 * opacity. Image state is not flushed. If the surface represents a buffer or
   1862 * the default layer, this function has no effect.
   1863 *
   1864 * @param surface
   1865 *     The surface to flush.
   1866 */
   1867static void __guac_common_surface_flush_properties(
   1868        guac_common_surface* surface) {
   1869
   1870    guac_socket* socket = surface->socket;
   1871
   1872    /* Only applicable to non-default visible layers */
   1873    if (surface->layer->index <= 0)
   1874        return;
   1875
   1876    /* Flush opacity */
   1877    if (surface->opacity_dirty) {
   1878        guac_protocol_send_shade(socket, surface->layer, surface->opacity);
   1879        surface->opacity_dirty = 0;
   1880    }
   1881
   1882    /* Flush location and hierarchy */
   1883    if (surface->location_dirty) {
   1884        guac_protocol_send_move(socket, surface->layer,
   1885                surface->parent, surface->x, surface->y, surface->z);
   1886        surface->location_dirty = 0;
   1887    }
   1888
   1889}
   1890
   1891static void __guac_common_surface_flush(guac_common_surface* surface) {
   1892
   1893    /* Flush final dirty rectangle to queue. */
   1894    __guac_common_surface_flush_to_queue(surface);
   1895
   1896    guac_common_surface_bitmap_rect* current = surface->bitmap_queue;
   1897    int i, j;
   1898    int original_queue_length;
   1899    int flushed = 0;
   1900
   1901    original_queue_length = surface->bitmap_queue_length;
   1902
   1903    /* Sort updates to make combination less costly */
   1904    qsort(surface->bitmap_queue, surface->bitmap_queue_length, sizeof(guac_common_surface_bitmap_rect),
   1905          __guac_common_surface_bitmap_rect_compare);
   1906
   1907    /* Flush all rects in queue */
   1908    for (i=0; i < surface->bitmap_queue_length; i++) {
   1909
   1910        /* Get next unflushed candidate */
   1911        guac_common_surface_bitmap_rect* candidate = current;
   1912        if (!candidate->flushed) {
   1913
   1914            int combined = 0;
   1915
   1916            /* Build up rect as much as possible */
   1917            for (j=i; j < surface->bitmap_queue_length; j++) {
   1918
   1919                if (!candidate->flushed) {
   1920
   1921                    /* Clip candidate within current bounds */
   1922                    __guac_common_bound_rect(surface, &candidate->rect, NULL, NULL);
   1923                    if (candidate->rect.width <= 0 || candidate->rect.height <= 0)
   1924                        candidate->flushed = 1;
   1925
   1926                    /* Combine if reasonable */
   1927                    else if (__guac_common_should_combine(surface, &candidate->rect, 0) || !surface->dirty) {
   1928                        __guac_common_mark_dirty(surface, &candidate->rect);
   1929                        candidate->flushed = 1;
   1930                        combined++;
   1931                    }
   1932
   1933                }
   1934
   1935                candidate++;
   1936
   1937            }
   1938
   1939            /* Re-add to queue if there's room and this update was modified or we expect others might be */
   1940            if ((combined > 1 || i < original_queue_length)
   1941                    && surface->bitmap_queue_length < GUAC_COMMON_SURFACE_QUEUE_SIZE)
   1942                __guac_common_surface_flush_to_queue(surface);
   1943
   1944            /* Flush as bitmap otherwise */
   1945            else if (surface->dirty) {
   1946
   1947                flushed++;
   1948
   1949                int opaque = __guac_common_surface_is_opaque(surface,
   1950                            &surface->dirty_rect);
   1951
   1952                /* Prefer WebP when reasonable */
   1953                if (__guac_common_surface_should_use_webp(surface,
   1954                            &surface->dirty_rect))
   1955                    __guac_common_surface_flush_to_webp(surface, opaque);
   1956
   1957                /* If not WebP, JPEG is the next best (lossy) choice */
   1958                else if (opaque && __guac_common_surface_should_use_jpeg(
   1959                            surface, &surface->dirty_rect))
   1960                    __guac_common_surface_flush_to_jpeg(surface);
   1961
   1962                /* Use PNG if no lossy formats are appropriate */
   1963                else
   1964                    __guac_common_surface_flush_to_png(surface, opaque);
   1965
   1966            }
   1967
   1968        }
   1969
   1970        current++;
   1971
   1972    }
   1973
   1974    /* Flush complete */
   1975    surface->bitmap_queue_length = 0;
   1976
   1977}
   1978
   1979void guac_common_surface_flush(guac_common_surface* surface) {
   1980
   1981    pthread_mutex_lock(&surface->_lock);
   1982
   1983    /* Flush any applicable layer properties */
   1984    __guac_common_surface_flush_properties(surface);
   1985
   1986    /* Flush surface contents */
   1987    __guac_common_surface_flush(surface);
   1988
   1989    pthread_mutex_unlock(&surface->_lock);
   1990
   1991}
   1992
   1993void guac_common_surface_dup(guac_common_surface* surface,
   1994        guac_client* client, guac_socket* socket) {
   1995
   1996    pthread_mutex_lock(&surface->_lock);
   1997
   1998    /* Do nothing if not realized */
   1999    if (!surface->realized)
   2000        goto complete;
   2001
   2002    /* Synchronize layer-specific properties if applicable */
   2003    if (surface->layer->index > 0) {
   2004
   2005        /* Synchronize opacity */
   2006        guac_protocol_send_shade(socket, surface->layer, surface->opacity);
   2007
   2008        /* Synchronize location and hierarchy */
   2009        guac_protocol_send_move(socket, surface->layer,
   2010                surface->parent, surface->x, surface->y, surface->z);
   2011
   2012        /* Synchronize multi-touch support level */
   2013        guac_protocol_send_set_int(surface->socket, surface->layer,
   2014                GUAC_PROTOCOL_LAYER_PARAMETER_MULTI_TOUCH,
   2015                surface->touches);
   2016
   2017    }
   2018
   2019    /* Sync size to new socket */
   2020    guac_protocol_send_size(socket, surface->layer,
   2021            surface->width, surface->height);
   2022
   2023    /* Send contents of layer, if non-empty */
   2024    if (surface->width > 0 && surface->height > 0) {
   2025
   2026        /* Get entire surface */
   2027        cairo_surface_t* rect = cairo_image_surface_create_for_data(
   2028                surface->buffer, CAIRO_FORMAT_ARGB32,
   2029                surface->width, surface->height, surface->stride);
   2030
   2031        /* Send PNG for rect */
   2032        guac_client_stream_png(client, socket, GUAC_COMP_OVER, surface->layer,
   2033                0, 0, rect);
   2034        cairo_surface_destroy(rect);
   2035
   2036    }
   2037
   2038complete:
   2039    pthread_mutex_unlock(&surface->_lock);
   2040
   2041}