Use init and clear for GMutex and GCond
[projects/chimara/chimara.git] / libchimara / graphics.c
index 13048f9aa41587f81af0520c6307bcf8c0787e43..f83ec0eb2001df91878fc52d5d9da7c1377fb6a0 100644 (file)
@@ -7,26 +7,18 @@
 extern GPrivate *glk_data_key;
 void on_size_prepared(GdkPixbufLoader *loader, gint width, gint height, struct image_info *info);
 void on_pixbuf_closed(GdkPixbufLoader *loader, gpointer data);
+glui32 draw_image_common(winid_t win, GdkPixbuf *pixbuf, glsi32 val1, glsi32 val2);
 
 static gboolean image_loaded;
 static gboolean size_determined;
 
 static struct image_info*
-load_image_in_cache(glui32 image, gint width, gint height)
+load_image_from_blorb(giblorb_result_t resource, glui32 image, gint width, gint height)
 {
        ChimaraGlkPrivate *glk_data = g_private_get(glk_data_key);
-       giblorb_err_t blorb_error = 0;
-       giblorb_result_t resource;
        GError *pixbuf_error = NULL;
        guchar *buffer;
 
-       /* Lookup the proper resource */
-       blorb_error = giblorb_load_resource(glk_data->resource_map, giblorb_method_FilePos, &resource, giblorb_ID_Pict, image);
-       if(blorb_error != giblorb_err_None) {
-               WARNING_S( "Error loading resource", giblorb_get_error_message(blorb_error) );
-               return NULL;
-       }
-
        struct image_info *info = g_new0(struct image_info, 1);
        info->resource_number = image;
 
@@ -64,28 +56,90 @@ load_image_in_cache(glui32 image, gint width, gint height)
        g_free(buffer);
 
        /* Wait for the PixbufLoader to finish loading the image */
-       g_mutex_lock(glk_data->resource_lock);
+       g_mutex_lock(&glk_data->resource_lock);
        while(!image_loaded) {
-               g_cond_wait(glk_data->resource_loaded, glk_data->resource_lock);
+               g_cond_wait(&glk_data->resource_loaded, &glk_data->resource_lock);
        }
-       g_mutex_unlock(glk_data->resource_lock);
+       g_mutex_unlock(&glk_data->resource_lock);
+
+       info->pixbuf = gdk_pixbuf_loader_get_pixbuf(loader);
+       g_object_ref(info->pixbuf);
+
+       g_object_unref(loader);
+       return info;
+}
+
+static struct image_info *
+load_image_from_file(const gchar *filename, glui32 image, gint width, gint height)
+{
+       GError *err = NULL;
+       
+       struct image_info *info = g_new0(struct image_info, 1);
+       info->resource_number = image;
+       
+       if(width > 0 && height > 0) {
+               info->scaled = TRUE;
+               info->pixbuf = gdk_pixbuf_new_from_file_at_size(filename, width, height, &err);
+       } else {
+               info->pixbuf = gdk_pixbuf_new_from_file(filename, &err);
+       }
+       if(!info->pixbuf) {
+               IO_WARNING("Error loading resource from alternative location", filename, err->message);
+               g_error_free(err);
+               g_free(info);
+               return NULL;
+       }
+       g_object_ref(info->pixbuf);
+
+       return info;
+}
+
+static struct image_info*
+load_image_in_cache(glui32 image, gint width, gint height)
+{
+       ChimaraGlkPrivate *glk_data = g_private_get(glk_data_key);
+       struct image_info *info = NULL;
+       
+       /* Lookup the proper resource */
+       if(!glk_data->resource_map) {
+               if(!glk_data->resource_load_callback) {
+                       WARNING("No resource map has been loaded yet.");
+                       return NULL;
+               }
+               gchar *filename = glk_data->resource_load_callback(CHIMARA_RESOURCE_IMAGE, image, glk_data->resource_load_callback_data);
+               if(!filename) {
+                       WARNING("Error loading resource from alternative location");
+                       return NULL;
+               }
+               info = load_image_from_file(filename, image, width, height);
+               g_free(filename);
+       } else {
+               giblorb_result_t resource;
+               giblorb_err_t blorb_error = giblorb_load_resource(glk_data->resource_map, giblorb_method_FilePos, &resource, giblorb_ID_Pict, image);
+               if(blorb_error != giblorb_err_None) {
+                       WARNING_S( "Error loading resource", giblorb_get_error_message(blorb_error) );
+                       return NULL;
+               }
+               info = load_image_from_blorb(resource, image, width, height);
+       }
+
+       if(info == NULL)
+               return NULL;
 
        /* Store the image in the cache */
+       gdk_threads_enter();
+
        if( g_slist_length(glk_data->image_cache) >= IMAGE_CACHE_MAX_NUM ) {
-               printf("Cache size exceeded\n");
                struct image_info *head = (struct image_info*) glk_data->image_cache->data;
-               gdk_pixbuf_unref(head->pixbuf);
+               g_object_unref(head->pixbuf);
                g_free(head);
                glk_data->image_cache = g_slist_remove_link(glk_data->image_cache, glk_data->image_cache);
        }
-       printf("Loading pixbuf\n");
-       info->pixbuf = gdk_pixbuf_loader_get_pixbuf(loader);
        info->width = gdk_pixbuf_get_width(info->pixbuf);
        info->height = gdk_pixbuf_get_height(info->pixbuf);
-       printf("Caching pixbuf\n");
        glk_data->image_cache = g_slist_prepend(glk_data->image_cache, info);
 
-       g_object_unref(loader);
+       gdk_threads_leave();
        return info;
 }
 
@@ -94,12 +148,12 @@ on_size_prepared(GdkPixbufLoader *loader, gint width, gint height, struct image_
 {
        ChimaraGlkPrivate *glk_data = g_private_get(glk_data_key);
 
-       g_mutex_lock(glk_data->resource_lock);
+       g_mutex_lock(&glk_data->resource_lock);
        info->width = width;
        info->height = height;
        size_determined = TRUE;
-       g_cond_broadcast(glk_data->resource_info_available);
-       g_mutex_unlock(glk_data->resource_lock);
+       g_cond_broadcast(&glk_data->resource_info_available);
+       g_mutex_unlock(&glk_data->resource_lock);
 }
 
 void
@@ -109,10 +163,10 @@ on_pixbuf_closed(GdkPixbufLoader *loader, gpointer data)
 
        ChimaraGlkPrivate *glk_data = g_private_get(glk_data_key);
 
-       g_mutex_lock(glk_data->resource_lock);
+       g_mutex_lock(&glk_data->resource_lock);
        image_loaded = TRUE;
-       g_cond_broadcast(glk_data->resource_loaded);
-       g_mutex_unlock(glk_data->resource_lock);
+       g_cond_broadcast(&glk_data->resource_loaded);
+       g_mutex_unlock(&glk_data->resource_lock);
 
        gdk_threads_leave();
 }
@@ -121,80 +175,139 @@ on_pixbuf_closed(GdkPixbufLoader *loader, gpointer data)
 void
 clear_image_cache(struct image_info *data, gpointer user_data)
 {
-       gdk_pixbuf_unref(data->pixbuf);
+       g_object_unref(data->pixbuf);
        g_free(data);
 }
 
 static struct image_info*
 image_cache_find(struct image_info* to_find)
 {
-       printf("Finding image %d\n", to_find->resource_number);
        ChimaraGlkPrivate *glk_data = g_private_get(glk_data_key);
        GSList *link = glk_data->image_cache;
 
+       gdk_threads_enter();
+
        /* Empty cache */
        if(link == NULL) {
-               printf("Cache is empty\n");
+               gdk_threads_leave();
                return NULL;
        }
 
        /* Iterate over the cache to find the correct image and size */
+       struct image_info *match = NULL;
        do {
                struct image_info *info = (struct image_info*) link->data;
-               printf("Examining cache entry %d\n", info->resource_number);
                if(info->resource_number == to_find->resource_number) {
                        /* Check size: are we looking for a scaled version or the original one? */
                        if(to_find->scaled) {
-                               if(info->width >= to_find->width && info->height >= to_find->height) {
-                                       return info; /* Found a good enough match */
+
+                               if(info->width == to_find->width && info->height == to_find->height) {
+                                       /* Prescaled image found */
+                                       gdk_threads_leave();
+                                       return info;
+                               }
+                               else if(info->width >= to_find->width && info->height >= to_find->height) {
+                                       /* Larger image found, needs to be scaled down in order to work */
+                                       gdk_threads_leave();
+                                       match = info;
                                }
                        } else {
                                if(!info->scaled) {
-                                       printf("Cache hit\n");
+                                       gdk_threads_leave();
                                        return info; /* Found a match */
                                }
                        }
                }
        } while( (link = g_slist_next(link)) );
 
-       return NULL; /* No match found */
+       gdk_threads_leave();
+
+       return match;
 }
 
+/**
+ * glk_image_get_info:
+ * @image: An image resource number.
+ * @width: Pointer to a location at which to store the image's width.
+ * @height: Pointer to a location at which to store the image's height.
+ *
+ * This gets information about the image resource with the given identifier. It
+ * returns %TRUE (1) if there is such an image, and %FALSE (0) if not. You can
+ * also pass pointers to width and height variables; if the image exists, the
+ * variables will be filled in with the width and height of the image, in
+ * pixels. (You can pass %NULL for either width or height if you don't care
+ * about that information.)
+ * 
+ * <note><para>
+ *   You should always use this function to measure the size of images when you 
+ *   are creating your display. Do this even if you created the images, and you
+ *   know how big they <quote>should</quote> be. This is because images may be 
+ *   scaled in translating from one platform to another, or even from one 
+ *   machine to another. A Glk library might display all images larger than 
+ *   their original size, because of screen resolution or player preference. 
+ *   Images will be scaled proportionally, but you still need to call 
+ *   glk_image_get_info() to determine their absolute size.
+ * </para></note>
+ * 
+ * Returns: %TRUE if @image is a valid identifier, %FALSE if not.
+ */
 glui32
 glk_image_get_info(glui32 image, glui32 *width, glui32 *height)
 {
-       printf("get_info(%d)\n", image);
        struct image_info *to_find = g_new0(struct image_info, 1);
        struct image_info *found;
        to_find->resource_number = image;
        to_find->scaled = FALSE; /* we want the original image size */
 
        if( !(found = image_cache_find(to_find)) ) {
-               printf("Cache miss for %d\n", image);
                found = load_image_in_cache(image, 0, 0);
                if(found == NULL)
                        return FALSE;
-       } else {
-               printf("Cache hit for %d\n", image);
        }
 
        if(width != NULL)
                *width = found->width;
-       if(width != NULL)
+       if(height != NULL)
                *height = found->height;
        return TRUE;
 }
 
+/**
+ * glk_image_draw:
+ * @win: A graphics or text buffer window.
+ * @image: An image resource number.
+ * @val1: The x coordinate at which to draw the image (if @win is a graphics 
+ * window); or, an <link linkend="chimara-imagealign-InlineUp">image 
+ * alignment</link> constant (if @win is a text window).
+ * @val2: The y coordinate at which to draw the image (if @win is a graphics
+ * window); this parameter is ignored if @win is a text buffer window.
+ *
+ * This draws the given image resource in the given window. The position of the
+ * image is given by @val1 and @val2, but their meaning varies depending on what
+ * kind of window you are drawing in. See <link 
+ * linkend="chimara-Graphics-in-Graphics-Windows">Graphics in Graphics 
+ * Windows</link> and <link linkend="Graphics-in-Text-Buffer-Windows">Graphics 
+ * in Text Buffer Windows</link>.
+ * 
+ * This function returns a flag indicating whether the drawing operation 
+ * succeeded.
+ * <note><para>
+ *   A %FALSE result can occur for many reasons. The image data might be 
+ *   corrupted; the library may not have enough memory to operate; there may be 
+ *   no image with the given identifier; the window might not support image 
+ *   display; and so on.
+ * </para></note>
+ *
+ * Returns: %TRUE if the operation succeeded, %FALSE if not.
+ */
 glui32
 glk_image_draw(winid_t win, glui32 image, glsi32 val1, glsi32 val2)
 {
-       printf("image_draw(%d)\n", image);
        VALID_WINDOW(win, return FALSE);
-       g_return_val_if_fail(win->type == wintype_Graphics, FALSE);
+       g_return_val_if_fail(win->type == wintype_Graphics || win->type == wintype_TextBuffer, FALSE);
 
        struct image_info *to_find = g_new0(struct image_info, 1);
        struct image_info *info;
-       GdkPixmap *canvas;
 
        /* Lookup the proper resource */
        to_find->resource_number = image;
@@ -206,37 +319,42 @@ glk_image_draw(winid_t win, glui32 image, glsi32 val1, glsi32 val2)
                        return FALSE;
        }
 
-       gdk_threads_enter();
-
-       gtk_image_get_pixmap( GTK_IMAGE(win->widget), &canvas, NULL );
-       if(canvas == NULL) {
-               WARNING("Could not get pixmap");
-               return FALSE;
-       }
-
-       printf("image info: %d x %d, scaled=%d, pixbufaddr=%d\n", info->width, info->height, (int)info->scaled, (int)info->pixbuf);
-       gdk_draw_pixbuf( GDK_DRAWABLE(canvas), NULL, info->pixbuf, 0, 0, val1, val2, -1, -1, GDK_RGB_DITHER_NONE, 0, 0 );
-
-       /* Update the screen */
-       gtk_widget_queue_draw(win->widget);
-
-       gdk_threads_leave();
-
-       return TRUE;
+       return draw_image_common(win, info->pixbuf, val1, val2);
 }
 
-
+/**
+ * glk_image_draw_scaled:
+ * @win: A graphics or text buffer window.
+ * @image: An image resource number.
+ * @val1: The x coordinate at which to draw the image (if @win is a graphics 
+ * window); or, an <link linkend="chimara-imagealign-InlineUp">image 
+ * alignment</link> constant (if @win is a text window).
+ * @val2: The y coordinate at which to draw the image (if @win is a graphics
+ * window); this parameter is ignored if @win is a text buffer window.
+ * @width: The width of the image.
+ * @height: The height of the image.
+ *
+ * This is similar to glk_image_draw(), but it scales the image to the given 
+ * @width and @height, instead of using the image's standard size. (You can 
+ * measure the standard size with glk_image_get_info().)
+ * 
+ * If @width or @height is zero, nothing is drawn. Since those arguments are 
+ * unsigned integers, they cannot be negative. If you pass in a negative number,
+ * it will be interpreted as a very large positive number, which is almost 
+ * certain to end badly. 
+ *
+ * Returns: %TRUE if the operation succeeded, %FALSE otherwise.
+ */
 glui32
 glk_image_draw_scaled(winid_t win, glui32 image, glsi32 val1, glsi32 val2, glui32 width, glui32 height)
 {
        VALID_WINDOW(win, return FALSE);
-       g_return_val_if_fail(win->type == wintype_Graphics, FALSE);
+       g_return_val_if_fail(win->type == wintype_Graphics || win->type == wintype_TextBuffer, FALSE);
 
        ChimaraGlkPrivate *glk_data = g_private_get(glk_data_key);
        struct image_info *to_find = g_new0(struct image_info, 1);
        struct image_info *info;
        struct image_info *scaled_info;
-       GdkPixmap *canvas;
 
        /* Lookup the proper resource */
        to_find->resource_number = image;
@@ -248,14 +366,6 @@ glk_image_draw_scaled(winid_t win, glui32 image, glsi32 val1, glsi32 val2, glui3
                        return FALSE;
        }
 
-       gdk_threads_enter();
-
-       gtk_image_get_pixmap( GTK_IMAGE(win->widget), &canvas, NULL );
-       if(canvas == NULL) {
-               WARNING("Could not get pixmap");
-               return FALSE;
-       }
-
        /* Scale the image if necessary */
        if(info->width != width || info->height != height) {
                GdkPixbuf *scaled = gdk_pixbuf_scale_simple(info->pixbuf, width, height, GDK_INTERP_BILINEAR);
@@ -273,79 +383,251 @@ glk_image_draw_scaled(winid_t win, glui32 image, glsi32 val1, glsi32 val2, glui3
                info = scaled_info;
        }
 
-       gdk_draw_pixbuf( GDK_DRAWABLE(canvas), NULL, info->pixbuf, 0, 0, val1, val2, -1, -1, GDK_RGB_DITHER_NONE, 0, 0 );
+       return draw_image_common(win, info->pixbuf, val1, val2);
+}
 
-       /* Update the screen */
-       gtk_widget_queue_draw(win->widget);
+/* Internal function: draws a pixbuf to a graphics window or text buffer */
+glui32
+draw_image_common(winid_t win, GdkPixbuf *pixbuf, glsi32 val1, glsi32 val2)
+{
+       switch(win->type) {
+       case wintype_Graphics:
+       {
+               gdk_threads_enter();
 
-       gdk_threads_leave();
+               cairo_t *cr = cairo_create(win->backing_store);
+               gdk_cairo_set_source_pixbuf(cr, pixbuf, val1, val2);
+               cairo_paint(cr);
+               cairo_destroy(cr);
 
+               /* Update the screen */
+               gtk_widget_queue_draw(win->widget);
+
+               gdk_threads_leave();
+       }
+               break;
+
+       case wintype_TextBuffer:
+       {
+               flush_window_buffer(win);
+
+               gdk_threads_enter();
+
+               GtkTextBuffer *buffer = gtk_text_view_get_buffer( GTK_TEXT_VIEW(win->widget) );
+               GtkTextIter end, start;
+               gtk_text_buffer_get_end_iter(buffer, &end);
+
+               gtk_text_buffer_insert_pixbuf(buffer, &end, pixbuf);
+               start = end;
+               gtk_text_iter_forward_char(&end);
+
+               gint height = 0;
+               switch(val1) {
+               case imagealign_InlineDown:
+                       height -= win->unit_height;
+                       break;
+               case imagealign_InlineCenter:
+                       height = -win->unit_height / 2;
+                       break;
+               case imagealign_InlineUp:
+               default:
+                       height = 0;
+               }
+
+               if(height != 0) {
+                       GtkTextTag *tag = gtk_text_buffer_create_tag(buffer, NULL, "rise", PANGO_SCALE * (-height), NULL);
+                       gtk_text_buffer_apply_tag(buffer, tag, &start, &end);
+               }
+
+               gdk_threads_leave();
+       }
+               break;
+       }
        return TRUE;
 }
 
+/**
+ * glk_window_set_background_color:
+ * @win: A graphics window.
+ * @color: a 32-bit RGB color value.
+ *
+ * This sets the window's background color. It does not change what is currently
+ * displayed; it only affects subsequent clears and resizes. The initial 
+ * background color of each window is white.
+ * 
+ * Colors are encoded in a 32-bit value: the top 8 bits must be zero, the next 8
+ * bits are the red value, the next 8 bits are the green value, and the bottom 8
+ * bits are the blue value. Color values range from 0 to 255.
+ * <note><para>
+ *   So <code>0x00000000</code> is black, <code>0x00FFFFFF</code> is white, and 
+ *   <code>0x00FF0000</code> is bright red.
+ * </para></note>
+ * 
+ * <note><para>
+ *   This function may only be used with graphics windows. To set background 
+ *   colors in a text window, use text styles with color hints; see <link 
+ *   linkend="chimara-Styles">Styles</link>.
+ * </para></note>
+ */
 void
-glk_window_set_background_color(winid_t win, glui32 color) {
+glk_window_set_background_color(winid_t win, glui32 color) 
+{
+       VALID_WINDOW(win, return);
+       g_return_if_fail(win->type == wintype_Graphics);
+       
        win->background_color = color;
 }
 
+static void
+glkcairo_set_source_glkcolor(cairo_t *cr, glui32 val)
+{
+       double r, g, b;
+       r = ((val & 0xff0000) >> 16) / 256.0;
+       g = ((val & 0x00ff00) >> 8) / 256.0;
+       b = (val & 0x0000ff) / 256.0;
+       cairo_set_source_rgb(cr, r, g, b);
+}
+
+/**
+ * glk_window_fill_rect:
+ * @win: A graphics window.
+ * @color: A 32-bit RGB color value, see glk_window_set_background_color().
+ * @left: The x coordinate of the top left corner of the rectangle.
+ * @top: The y coordinate of the top left corner of the rectangle.
+ * @width: The width of the rectangle.
+ * @height: The height of the rectangle.
+ *
+ * This fills the given rectangle with the given color. It is legitimate for
+ * part of the rectangle to fall outside the window. If width or height is zero,
+ * nothing is drawn. 
+ */
 void
 glk_window_fill_rect(winid_t win, glui32 color, glsi32 left, glsi32 top, glui32 width, glui32 height)
 {
        VALID_WINDOW(win, return);
        g_return_if_fail(win->type == wintype_Graphics);
 
-
        gdk_threads_enter();
 
-       GdkPixmap *map;
-       gtk_image_get_pixmap( GTK_IMAGE(win->widget), &map, NULL );
-       gdk_draw_rectangle( GDK_DRAWABLE(map), win->widget->style->white_gc, TRUE, left, top, width, height);
+       cairo_t *cr = cairo_create(win->backing_store);
+       glkcairo_set_source_glkcolor(cr, color);
+       cairo_rectangle(cr, (double)left, (double)top, (double)width, (double)height);
+       cairo_fill(cr);
        gtk_widget_queue_draw(win->widget);
+       cairo_destroy(cr);
 
        gdk_threads_leave();
 }
 
+/**
+ * glk_window_erase_rect:
+ * @win: A graphics window.
+ * @left: The x coordinate of the top left corner of the rectangle.
+ * @top: The y coordinate of the top left corner of the rectangle.
+ * @width: The width of the rectangle.
+ * @height: The height of the rectangle.
+ *
+ * This fills the given rectangle with the window's background color.
+ * 
+ * You can also fill an entire graphics window with its background color by 
+ * calling glk_window_clear().
+ */
 void
 glk_window_erase_rect(winid_t win, glsi32 left, glsi32 top, glui32 width, glui32 height)
 {
        glk_window_fill_rect(win, win->background_color, left, top, width, height);
 }
 
+/**
+ * glk_window_flow_break:
+ * @win: A window.
+ *
+ * You may wish to <quote>break</quote> the stream of text down below the 
+ * current margin image. Since lines of text can be in any font and size, you 
+ * cannot do this by counting newlines. Instead, use this function.
+ *
+ * If the current point in the text is indented around a margin-aligned image, 
+ * this acts like the correct number of newlines to start a new line below the 
+ * image. (If there are several margin-aligned images, it goes below all of 
+ * them.) If the current point is not beside a margin-aligned image, this call 
+ * has no effect.
+ *
+ * When a text buffer window is resized, a flow-break behaves cleverly; it may 
+ * become active or inactive as necessary. You can consider this function to 
+ * insert an invisible mark in the text stream. The mark works out how many 
+ * newlines it needs to be whenever the text is formatted for display.
+ * 
+ * An example of the use of glk_window_flow_break(): If you display a 
+ * left-margin image at the start of every line, they can stack up in a strange 
+ * diagonal way that eventually squeezes all the text off the screen. 
+ * <note><para>
+ *   If you can't picture this, draw some diagrams. Make the margin images more 
+ *   than one line tall, so that each line starts already indented around the 
+ *   last image.
+ * </para></note>
+ * To avoid this problem, call glk_window_flow_break() immediately before 
+ * glk_image_draw() for every margin-aligned image.
+ * 
+ * In all windows other than text buffers, glk_window_flow_break() has no 
+ * effect. 
+ *
+ * <warning><para>
+ *   This function is not implemented yet.
+ * </para></warning>
+ */
 void glk_window_flow_break(winid_t win)
 {
+       VALID_WINDOW(win, return);
 }
 
-/*** Called when the graphics window is resized. Resize the backing pixmap if necessary ***/
-void
-on_graphics_size_allocate(GtkWidget *widget, GtkAllocation *allocation, winid_t win)
-{ 
-       GdkPixmap *oldmap;
-       gtk_image_get_pixmap( GTK_IMAGE(widget), &oldmap, NULL );
-       gint oldwidth = 0;
-       gint oldheight = 0;
-       /* Determine whether a pixmap exists with the correct size */
+/* Called when the graphics window is resized, restacked, or moved. Resize the
+backing store if necessary. */
+gboolean
+on_graphics_configure(GtkWidget *widget, GdkEventConfigure *event, winid_t win)
+{
+       int oldwidth = 0, oldheight = 0;
+
+       /* Determine whether the backing store can stay the same size */
        gboolean needs_resize = FALSE;
-       if(oldmap == NULL)
+       if(win->backing_store == NULL)
                needs_resize = TRUE;
        else {
-               gdk_drawable_get_size( GDK_DRAWABLE(oldmap), &oldwidth, &oldheight );
-               if(oldwidth != allocation->width || oldheight != allocation->height)
+               oldwidth = cairo_image_surface_get_width(win->backing_store);
+               oldheight = cairo_image_surface_get_height(win->backing_store);
+               if(oldwidth != event->width || oldheight != event->height)
                        needs_resize = TRUE;
        }
 
        if(needs_resize) {
-               /* Create a new pixmap */
-               GdkPixmap *newmap = gdk_pixmap_new(widget->window, allocation->width, allocation->height, -1);
-               gdk_draw_rectangle( GDK_DRAWABLE(newmap), widget->style->white_gc, TRUE, 0, 0, allocation->width, allocation->height);
-
-               /* Copy the contents of the old pixmap */
-               if(oldmap != NULL)
-                       gdk_draw_drawable( GDK_DRAWABLE(newmap), widget->style->white_gc, GDK_DRAWABLE(oldmap), 0, 0, 0, 0, oldwidth, oldheight);
-               
-               /* Use the new pixmap */
-               gtk_image_set_from_pixmap( GTK_IMAGE(widget), newmap, NULL );
-               g_object_unref(newmap);
+               /* Create a new backing store */
+               cairo_surface_t *new_backing_store = gdk_window_create_similar_surface( gtk_widget_get_window(widget), CAIRO_CONTENT_COLOR, gtk_widget_get_allocated_width(widget), gtk_widget_get_allocated_height(widget) );
+               cairo_t *cr = cairo_create(new_backing_store);
+
+               /* Clear to background color */
+               glkcairo_set_source_glkcolor(cr, win->background_color);
+               cairo_paint(cr);
+
+               if(win->backing_store != NULL) {
+                       /* Copy the contents of the old backing store */
+                       cairo_set_source_surface(cr, win->backing_store, 0, 0);
+                       cairo_paint(cr);
+                       cairo_surface_destroy(win->backing_store);
+               }
+
+               cairo_destroy(cr);
+               /* Use the new backing store */
+               win->backing_store = new_backing_store;
        }
+
+       return TRUE; /* Event handled, stop processing */
 }
 
+/* Draw the backing store to the screen. Called whenever the drawing area is
+exposed. */
+gboolean
+on_graphics_draw(GtkWidget *widget, cairo_t *cr, winid_t win)
+{
+       cairo_set_source_surface(cr, win->backing_store, 0, 0);
+       cairo_paint(cr);
+       return FALSE;
+}