GUAC-236: Ensure buffers are resized to fit draw operations (unless they are within layers).

src/guacenc/buffer.c

@@ -25,6 +25,7 @@
 
 #include <cairo/cairo.h>
 
+#include <stdbool.h>
 #include <stdlib.h>
 
 guacenc_buffer* guacenc_buffer_alloc() {
@@ -115,3 +116,24 @@ int guacenc_buffer_resize(guacenc_buffer* buffer, int width, int height) {
 
 }
 
+int guacenc_buffer_fit(guacenc_buffer* buffer, int x, int y) {
+
+    /* Increase width to fit X (if necessary) */
+    int new_width = buffer->width;
+    if (new_width < x+1)
+        new_width = x+1;
+
+    /* Increase height to fit Y (if necessary) */
+    int new_height = buffer->height;
+    if (new_height < y+1)
+        new_height = y+1;
+
+    /* Resize buffer if size needs to change to fit X/Y coordinate */
+    if (new_width != buffer->width || new_height != buffer->height)
+        return guacenc_buffer_resize(buffer, new_width, new_height);
+
+    /* No change necessary */
+    return 0;
+
+}
+

src/guacenc/buffer.h

@@ -27,12 +27,20 @@
 
 #include <cairo/cairo.h>
 
+#include <stdbool.h>
+
 /**
  * The image and size storage for either a buffer (a Guacamole layer with a
  * negative index) or a layer (a Guacamole layer with a non-negative index).
  */
 typedef struct guacenc_buffer {
 
+    /**
+     * Whether this buffer should be automatically resized to fit any draw
+     * operation.
+     */
+    bool autosize;
+
     /**
      * The width of this buffer or layer, in pixels.
      */
@@ -107,5 +115,26 @@ void guacenc_buffer_free(guacenc_buffer* buffer);
  */
 int guacenc_buffer_resize(guacenc_buffer* buffer, int width, int height);
 
+/**
+ * Resizes the given buffer as necessary to contain at the given X/Y
+ * coordinate, allocating or freeing memory as necessary, and updating the
+ * buffer's width, height, and stride properties. If the buffer already
+ * contains the given coordinate, this function has no effect.
+ *
+ * @param buffer
+ *     The buffer to resize.
+ *
+ * @param x
+ *     The X coordinate to ensure is within the buffer.
+ *
+ * @param y
+ *     The Y coordinate to ensure is within the buffer.
+ *
+ * @return
+ *     Zero if the resize operation is successful or no resize was performed,
+ *     non-zero if the resize operation failed.
+ */
+int guacenc_buffer_fit(guacenc_buffer* buffer, int x, int y);
+
 #endif
 

src/guacenc/image-stream.c

@@ -132,18 +132,19 @@ int guacenc_image_stream_end(guacenc_image_stream* stream,
     if (surface == NULL)
         return 1;
 
-    /* Draw surface to buffer */
-    if (buffer->cairo != NULL) {
-
     /* Get surface dimensions */
     int width = cairo_image_surface_get_width(surface);
     int height = cairo_image_surface_get_height(surface);
 
-        /* Paint surface contents to buffer */
+    /* Expand the buffer as necessary to fit the draw operation */
+    if (buffer->autosize)
+        guacenc_buffer_fit(buffer, stream->x + width, stream->y + height);
+
+    /* Draw surface to buffer */
+    if (buffer->cairo != NULL) {
         cairo_set_source_surface(buffer->cairo, surface, stream->x, stream->y);
         cairo_rectangle(buffer->cairo, stream->x, stream->y, width, height);
         cairo_fill(buffer->cairo);
-
     }
 
     cairo_surface_destroy(surface);

src/guacenc/instruction-copy.c

@@ -57,6 +57,10 @@ int guacenc_handle_copy(guacenc_display* display, int argc, char** argv) {
     if (dst == NULL)
         return 1;
 
+    /* Expand the destination buffer as necessary to fit the draw operation */
+    if (dst->autosize)
+        guacenc_buffer_fit(dst, dx + width, dy + height);
+
     /* Copy rectangle from source to destination */
     if (src->surface != NULL && dst->cairo != NULL) {
         cairo_set_operator(dst->cairo, guacenc_display_cairo_operator(mask));

src/guacenc/instruction-rect.c

@@ -50,6 +50,10 @@ int guacenc_handle_rect(guacenc_display* display, int argc, char** argv) {
     if (buffer == NULL)
         return 1;
 
+    /* Expand the buffer as necessary to fit the draw operation */
+    if (buffer->autosize)
+        guacenc_buffer_fit(buffer, x + width, y + height);
+
     /* Set path to rectangle */
     if (buffer->cairo != NULL)
         cairo_rectangle(buffer->cairo, x, y, width, height);