This patch implements support for icons in user-defined menus into Openbox

Image loading is done using the Imlib2 library.
I chose Imlib2 because it's pretty fast, it's easy to use, supports many file
formats (tested xpm, gif, jpeg, png) and doesn't introduce too much bloat (it
depends :)).

I ported the patch to 3.4.7-pre3 and added some enhancements. Caching is much
better now, and icons can be disabled at compile time using --disable-imlib2
option.

What's new?
Syntax of configuration files (namely rc.xml and menu.xml) has been changed
slightly to allow users to associate icons to menu entries. This is done by
specifying path to icon file in the new "icon" attribute in "<item>" element,
e.g:
<item label="Vim" icon="/usr/share/pixmaps/vim-32.xpm">
  <action name="Execute"><execute>x-terminal-emulator -T Vim -e
vim</execute></action>
</item>

If user doesn't want to display any icons in his user-defined menus, he/she can
disable icons in rc.xml, inside "<menu>" section:
<menu>
 ...
  <showIcons>no</showIcons>
 ...
</menu>
Default value is "yes".
(New boolean variable "config_menu_user_show_icons" has been added to source
code.)

An icon is loaded (using menu_item_attach_icon()) when a new entry of menu is
created. Fortunately, I haven't notice any performance problems because of this
:).

4 files changed, 20 insertions, 0 deletions

diff --git a/obrender/image.c b/obrender/image.c
index 924504fd..c65cd2a5 100644
--- a/obrender/image.c
+++ b/obrender/image.c
@@ -325,6 +325,12 @@ RrImage* RrImageNew(RrImageCache *cache)
     return self;
 }
 
+/*! Set function that will be called just before RrImage is destroyed. */
+void RrImageSetDestroyFunc(RrImage *image, RrImageDestroyFunc func)
+{
+    image->destroy_func = func;
+}
+
 void RrImageRef(RrImage *self)
 {
     ++self->ref;
@@ -339,6 +345,8 @@ void RrImageUnref(RrImage *self)
                 "Image 0x%lx", (gulong)self);
 #endif
 */
+        if (self->destroy_func)
+            self->destroy_func(self);
         while (self->n_original > 0)
             RemovePicture(self, &self->original, 0, &self->n_original);
         while (self->n_resized > 0)
diff --git a/obrender/imagecache.c b/obrender/imagecache.c
index 9c605f9d..fde1e7a0 100644
--- a/obrender/imagecache.c
+++ b/obrender/imagecache.c
@@ -34,6 +34,7 @@ RrImageCache* RrImageCacheNew(gint max_resized_saved)
     self->max_resized_saved = max_resized_saved;
     self->table = g_hash_table_new((GHashFunc)RrImagePicHash,
                                    (GEqualFunc)RrImagePicEqual);
+    self->file_name_table = NULL;
     return self;
 }
 
@@ -46,6 +47,7 @@ void RrImageCacheUnref(RrImageCache *self)
 {
     if (self && --self->ref == 0) {
         g_assert(g_hash_table_size(self->table) == 0);
+        g_assert(self->file_name_table == NULL);
         g_hash_table_unref(self->table);
 
         g_free(self);
diff --git a/obrender/imagecache.h b/obrender/imagecache.h
index 4ad2deae..a61fae67 100644
--- a/obrender/imagecache.h
+++ b/obrender/imagecache.h
@@ -46,6 +46,10 @@ struct _RrImageCache {
     gint max_resized_saved;
 
     GHashTable *table;
+
+    /* Used to find out if an image file has already been loaded.
+       Quick file_name -> RrImage lookup. */
+    GHashTable *file_name_table;
 };
 
 #endif
diff --git a/obrender/render.h b/obrender/render.h
index 7bea1b54..7aa9d698 100644
--- a/obrender/render.h
+++ b/obrender/render.h
@@ -232,6 +232,8 @@ struct _RrImagePic {
     gint sum;
 };
 
+typedef void (*RrImageDestroyFunc)(RrImage *image);
+
 /*! An RrImage is a sort of meta-image.  It can contain multiple versions of
   an image at different sizes, which may or may not be completely different
   pictures */
@@ -250,6 +252,10 @@ struct _RrImage {
       RrImage. */
     RrImagePic **resized;
     gint n_resized;
+ 
+    /* This function (if not NULL) will be called just before destroying
+      RrImage. */
+    RrImageDestroyFunc destroy_func;
 };
 
 /* these are the same on all endian machines because it seems to be dependant