[gnome-control-center] background: don't use the GnomeBG thumbnails for the preview area

[Cosimo Cecchi <cosimoc src gnome org>]

commit 7cef6dc582a9cdf3a7d3df30a3679a2ab9e94f26
Author: Cosimo Cecchi <cosimoc gnome org>
Date:   Tue Mar 29 23:44:58 2011 -0400

    background: don't use the GnomeBG thumbnails for the preview area
    
    Instead, use gnome_bg_draw(), which renders the preview directly at the
    desired size.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=646180

 panels/background/cc-background-item.c  |   56 ++++++++++++++++++++++--------
 panels/background/cc-background-item.h  |    3 +-
 panels/background/cc-background-panel.c |    8 ++--
 3 files changed, 47 insertions(+), 20 deletions(-)
---
diff --git a/panels/background/cc-background-item.c b/panels/background/cc-background-item.c
index af1951a..a29a126 100644
--- a/panels/background/cc-background-item.c
+++ b/panels/background/cc-background-item.c
@@ -156,12 +156,26 @@ update_size (CcBackgroundItem *item)
 	}
 }
 
+static GdkPixbuf *
+render_at_size (GnomeBG *bg,
+                gint width,
+                gint height)
+{
+        GdkPixbuf *pixbuf;
+
+        pixbuf = gdk_pixbuf_new (GDK_COLORSPACE_RGB, FALSE, 8, width, height);
+        gnome_bg_draw (bg, pixbuf, gdk_screen_get_default (), FALSE);
+
+        return pixbuf;
+}
+
 GIcon *
 cc_background_item_get_frame_thumbnail (CcBackgroundItem             *item,
                                         GnomeDesktopThumbnailFactory *thumbs,
                                         int                           width,
                                         int                           height,
-                                        int                           frame)
+                                        int                           frame,
+                                        gboolean                      force_size)
 {
         GdkPixbuf *pixbuf = NULL;
         GIcon *icon = NULL;
@@ -171,19 +185,31 @@ cc_background_item_get_frame_thumbnail (CcBackgroundItem             *item,
 
         set_bg_properties (item);
 
-        if (frame >= 0)
-                pixbuf = gnome_bg_create_frame_thumbnail (item->priv->bg,
-                                                          thumbs,
-                                                          gdk_screen_get_default (),
-                                                          width,
-                                                          height,
-                                                          frame);
-        else
-                pixbuf = gnome_bg_create_thumbnail (item->priv->bg,
-                                                    thumbs,
-                                                    gdk_screen_get_default(),
-                                                    width,
-                                                    height);
+        if (force_size) {
+                /* FIXME: this doesn't play nice with slideshow stepping at all,
+                 * because it will always render the current slideshow frame, which
+                 * might not be what we want.
+                 * We're lacking an API to draw a high-res GnomeBG manually choosing
+                 * the slideshow frame though, so we can't do much better than this
+                 * for now.
+                 */
+                pixbuf = render_at_size (item->priv->bg, width, height);
+        } else {
+                if (frame >= 0) {
+                        pixbuf = gnome_bg_create_frame_thumbnail (item->priv->bg,
+                                                                  thumbs,
+                                                                  gdk_screen_get_default (),
+                                                                  width,
+                                                                  height,
+                                                                  frame);
+                } else {
+                        pixbuf = gnome_bg_create_thumbnail (item->priv->bg,
+                                                            thumbs,
+                                                            gdk_screen_get_default (),
+                                                            width,
+                                                            height);
+                }
+        }
 
         if (pixbuf != NULL
             && frame != -2
@@ -217,7 +243,7 @@ cc_background_item_get_thumbnail (CcBackgroundItem             *item,
                                   int                           width,
                                   int                           height)
 {
-        return cc_background_item_get_frame_thumbnail (item, thumbs, width, height, -1);
+        return cc_background_item_get_frame_thumbnail (item, thumbs, width, height, -1, FALSE);
 }
 
 static void
diff --git a/panels/background/cc-background-item.h b/panels/background/cc-background-item.h
index 4781dc7..dc91703 100644
--- a/panels/background/cc-background-item.h
+++ b/panels/background/cc-background-item.h
@@ -79,7 +79,8 @@ GIcon     *        cc_background_item_get_frame_thumbnail (CcBackgroundItem
                                                            GnomeDesktopThumbnailFactory *thumbs,
                                                            int                           width,
                                                            int                           height,
-                                                           int                           frame);
+                                                           int                           frame,
+                                                           gboolean                      force_size);
 
 GDesktopBackgroundStyle   cc_background_item_get_placement  (CcBackgroundItem *item);
 GDesktopBackgroundShading cc_background_item_get_shading    (CcBackgroundItem *item);
diff --git a/panels/background/cc-background-panel.c b/panels/background/cc-background-panel.c
index 752317c..42b37cc 100644
--- a/panels/background/cc-background-panel.c
+++ b/panels/background/cc-background-panel.c
@@ -701,10 +701,10 @@ preview_draw_cb (GtkWidget         *widget,
     {
       GIcon *icon;
       icon = cc_background_item_get_frame_thumbnail (priv->current_background,
-                                                priv->thumb_factory,
-                                                preview_width,
-                                                preview_height,
-                                                -2);
+                                                     priv->thumb_factory,
+                                                     preview_width,
+                                                     preview_height,
+                                                     -2, TRUE);
       pixbuf = GDK_PIXBUF (icon);
     }