GUACAMOLE-1302: Add surface/display level support for forcing lossless compression.

src/common/common/display.h

@@ -99,6 +99,13 @@ typedef struct guac_common_display {
      */
     guac_common_display_layer* buffers;
 
+    /**
+     * Non-zero if all graphical updates for this display should use lossless
+     * compression, 0 otherwise. By default, newly-created displays will use
+     * lossy compression when heuristics determine it is appropriate.
+     */
+    int lossless;
+
     /**
      * Mutex which is locked internally when access to the display must be
      * synchronized. All public functions of guac_common_display should be
@@ -228,5 +235,27 @@ void guac_common_display_free_layer(guac_common_display* display,
 void guac_common_display_free_buffer(guac_common_display* display,
         guac_common_display_layer* display_buffer);
 
+/**
+ * Sets the overall lossless compression policy of the given display to the
+ * given value, affecting all current and future layers/buffers maintained by
+ * the display. By default, newly-created displays will use lossy compression
+ * for graphical updates when heuristics determine that doing so is
+ * appropriate. Specifying a non-zero value here will force all graphical
+ * updates to always use lossless compression, whereas specifying zero will
+ * restore the default policy.
+ *
+ * Note that this can also be adjusted on a per-layer / per-buffer basis with
+ * guac_common_surface_set_lossless().
+ *
+ * @param display
+ *     The display to modify.
+ *
+ * @param lossless
+ *     Non-zero if all graphical updates for this display should use lossless
+ *     compression, 0 otherwise.
+ */
+void guac_common_display_set_lossless(guac_common_display* display,
+        int lossless);
+
 #endif
 

src/common/common/surface.h

@@ -126,6 +126,13 @@ typedef struct guac_common_surface {
      */
     int touches;
 
+    /**
+     * Non-zero if all graphical updates for this surface should use lossless
+     * compression, 0 otherwise. By default, newly-created surfaces will use
+     * lossy compression when heuristics determine it is appropriate.
+     */
+    int lossless;
+
     /**
      * The X coordinate of the upper-left corner of this layer, in pixels,
      * relative to its parent layer. This is only applicable to visible
@@ -510,5 +517,23 @@ void guac_common_surface_dup(guac_common_surface* surface, guac_user* user,
 void guac_common_surface_set_multitouch(guac_common_surface* surface,
         int touches);
 
+/**
+ * Sets the lossless compression policy of the given surface to the given
+ * value. By default, newly-created surfaces will use lossy compression for
+ * graphical updates when heuristics determine that doing so is appropriate.
+ * Specifying a non-zero value here will force all graphical updates to always
+ * use lossless compression, whereas specifying zero will restore the default
+ * policy.
+ *
+ * @param surface
+ *     The surface to modify.
+ *
+ * @param lossless
+ *     Non-zero if all graphical updates for this surface should use lossless
+ *     compression, 0 otherwise.
+ */
+void guac_common_surface_set_lossless(guac_common_surface* surface,
+        int lossless);
+
 #endif
 

src/common/display.c

@@ -182,6 +182,30 @@ void guac_common_display_dup(guac_common_display* display, guac_user* user,
 
 }
 
+void guac_common_display_set_lossless(guac_common_display* display,
+        int lossless) {
+
+    pthread_mutex_lock(&display->_lock);
+
+    /* Update lossless setting to be applied to all newly-allocated
+     * layers/buffers */
+    display->lossless = lossless;
+
+    /* Update losslessness of all allocated layers/buffers */
+    guac_common_display_layer* current = display->layers;
+    while (current != NULL) {
+        guac_common_surface_set_lossless(current->surface, lossless);
+        current = current->next;
+    }
+
+    /* Update losslessness of default display layer (not included within layers
+     * list) */
+    guac_common_surface_set_lossless(display->default_surface, lossless);
+
+    pthread_mutex_unlock(&display->_lock);
+
+}
+
 void guac_common_display_flush(guac_common_display* display) {
 
     pthread_mutex_lock(&display->_lock);
@@ -287,6 +311,9 @@ guac_common_display_layer* guac_common_display_alloc_layer(
     guac_common_surface* surface = guac_common_surface_alloc(display->client,
             display->client->socket, layer, width, height);
 
+    /* Apply current display losslessness */
+    guac_common_surface_set_lossless(surface, display->lossless);
+
     /* Add layer and surface to list */
     guac_common_display_layer* display_layer =
         guac_common_display_add_layer(&display->layers, layer, surface);
@@ -308,6 +335,9 @@ guac_common_display_layer* guac_common_display_alloc_buffer(
     guac_common_surface* surface = guac_common_surface_alloc(display->client,
             display->client->socket, buffer, width, height);
 
+    /* Apply current display losslessness */
+    guac_common_surface_set_lossless(surface, display->lossless);
+
     /* Add buffer and surface to list */
     guac_common_display_layer* display_layer =
         guac_common_display_add_layer(&display->buffers, buffer, surface);

src/common/surface.c

@@ -116,6 +116,15 @@ void guac_common_surface_set_multitouch(guac_common_surface* surface,
 
 }
 
+void guac_common_surface_set_lossless(guac_common_surface* surface,
+        int lossless) {
+
+    pthread_mutex_lock(&surface->_lock);
+    surface->lossless = lossless;
+    pthread_mutex_unlock(&surface->_lock);
+
+}
+
 void guac_common_surface_move(guac_common_surface* surface, int x, int y) {
 
     pthread_mutex_lock(&surface->_lock);
@@ -534,6 +543,10 @@ static int __guac_common_surface_png_optimality(guac_common_surface* surface,
 static int __guac_common_surface_should_use_jpeg(guac_common_surface* surface,
         const guac_common_rect* rect) {
 
+    /* Do not use JPEG if lossless quality is required */
+    if (surface->lossless)
+        return 0;
+
     /* Calculate the average framerate for the given rect */
     int framerate = __guac_common_surface_calculate_framerate(surface, rect);
 
@@ -1806,7 +1819,8 @@ static void __guac_common_surface_flush_to_webp(guac_common_surface* surface,
         /* Send WebP for rect */
         guac_client_stream_webp(surface->client, socket, GUAC_COMP_OVER, layer,
                 surface->dirty_rect.x, surface->dirty_rect.y, rect,
-                guac_common_surface_suggest_quality(surface->client), 0);
+                guac_common_surface_suggest_quality(surface->client),
+                surface->lossless ? 1 : 0);
 
         cairo_surface_destroy(rect);
         surface->realized = 1;