add an option to set the preferred client icon size

_NET_WM_ICON contains a list of icons and until now, the first one was
picked without regard to it's size. This adds a global option to set
the preferred icon size. When getting the client icon, the best size
match is picked. The size can be set via
awesome.set_preferred_icon_size() and the default is 0, which will pick
the smallest non-zero size icon available.

Signed-off-by: Lukáš Hrázký <lukkash@email.cz>

awesome.c

@@ -543,6 +543,9 @@ main(int argc, char **argv)
     /* We have no clue where the input focus is right now */
     globalconf.focus.need_update = true;
 
+    /* set the default preferred icon size */
+    globalconf.preferred_icon_size = 0;
+
     /* XLib sucks */
     XkbIgnoreExtension(True);
 

ewmh.c

@@ -662,27 +662,45 @@ ewmh_window_icon_get_unchecked(xcb_window_t w)
 }
 
 static cairo_surface_t *
-ewmh_window_icon_from_reply(xcb_get_property_reply_t *r)
+ewmh_window_icon_from_reply(xcb_get_property_reply_t *r, uint32_t preferred_size)
 {
-    uint32_t *data;
-    uint64_t len;
+    uint32_t *data, *end, *found_data = 0;
+    uint32_t found_size = 0;
 
     if(!r || r->type != XCB_ATOM_CARDINAL || r->format != 32 || r->length < 2)
         return 0;
 
     data = (uint32_t *) xcb_get_property_value(r);
-    if (!data)
-        return 0;
+    if (!data) return 0;
 
-    /* Check that the property is as long as it should be, handling integer
-     * overflow. <uint32_t> times <another uint32_t casted to uint64_t> always
-     * fits into an uint64_t and thus this multiplication cannot overflow.
+    end = data + r->length;
+
+    /* Goes over the icon data and picks the icon that best matches the size preference.
+     * In case the size match is not exact, picks the closest bigger size if present,
+     * closest smaller size otherwise.
      */
-    len = data[0] * (uint64_t) data[1];
-    if (!data[0] || !data[1] || len > r->length - 2)
-        return 0;
+    while (data + 1 < end) {
+        /* check whether the data size specified by width and height fits into the array we got */
+        uint64_t data_size = (uint64_t) data[0] * data[1];
+        if (data_size > (uint64_t) (end - data - 2)) break;
 
-    return draw_surface_from_data(data[0], data[1], data + 2);
+        /* use the greater of the two dimensions to match against the preferred size */
+        uint32_t size = MAX(data[0], data[1]);
+        /* pick the icon if it's a better match than the one we already have */
+        if (data[0] && data[1] && (
+            (found_size < preferred_size && size > found_size) ||
+            (found_size > preferred_size && size >= preferred_size && size < found_size)))
+        {
+            found_data = data;
+            found_size = size;
+        }
+
+        data += data_size + 2;
+    }
+
+    if (!found_data) return 0;
+
+    return draw_surface_from_data(found_data[0], found_data[1], found_data + 2);
 }
 
 /** Get NET_WM_ICON.
@@ -690,10 +708,10 @@ ewmh_window_icon_from_reply(xcb_get_property_reply_t *r)
  * \return The number of elements on stack.
  */
 cairo_surface_t *
-ewmh_window_icon_get_reply(xcb_get_property_cookie_t cookie)
+ewmh_window_icon_get_reply(xcb_get_property_cookie_t cookie, uint32_t preferred_size)
 {
     xcb_get_property_reply_t *r = xcb_get_property_reply(globalconf.connection, cookie, NULL);
-    cairo_surface_t *surface = ewmh_window_icon_from_reply(r);
+    cairo_surface_t *surface = ewmh_window_icon_from_reply(r, preferred_size);
     p_delete(&r);
     return surface;
 }

ewmh.h

@@ -41,7 +41,7 @@ void ewmh_process_client_strut(client_t *);
 void ewmh_update_strut(xcb_window_t, strut_t *);
 void ewmh_update_window_type(xcb_window_t window, uint32_t type);
 xcb_get_property_cookie_t ewmh_window_icon_get_unchecked(xcb_window_t);
-cairo_surface_t *ewmh_window_icon_get_reply(xcb_get_property_cookie_t);
+cairo_surface_t *ewmh_window_icon_get_reply(xcb_get_property_cookie_t, uint32_t preferred_size);
 
 #endif
 // vim: filetype=c:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80

globalconf.h

@@ -167,6 +167,8 @@ typedef struct
     struct xkb_context *xkb_ctx;
     /* xkb state of dead keys on keyboard */
     struct xkb_state *xkb_state;
+    /** The preferred size of client icons for this screen */
+    uint32_t preferred_icon_size;
 } awesome_t;
 
 extern awesome_t globalconf;

luaa.c

@@ -162,6 +162,21 @@ luaA_load_image(lua_State *L)
     return 1;
 }
 
+/** Set the preferred size for client icons.
+ *
+ * The closest equal or bigger size is picked if present, otherwise the closest
+ * smaller size is picked. The default is 0 pixels, ie. the smallest icon.
+ *
+ * @param size The size of the icons in pixels.
+ * @function set_preferred_icon_size
+ */
+static int
+luaA_set_preferred_icon_size(lua_State *L)
+{
+    globalconf.preferred_icon_size = luaL_checknumber(L, 1);
+    return 0;
+}
+
 /** UTF-8 aware string length computing.
  * \param L The Lua VM state.
  * \return The number of elements pushed on stack.
@@ -407,6 +422,7 @@ luaA_init(xdgHandle* xdg)
         { "emit_signal", luaA_awesome_emit_signal },
         { "systray", luaA_systray },
         { "load_image", luaA_load_image },
+        { "set_preferred_icon_size", luaA_set_preferred_icon_size },
         { "register_xproperty", luaA_register_xproperty },
         { "set_xproperty", luaA_set_xproperty },
         { "get_xproperty", luaA_get_xproperty },

property.c

@@ -273,7 +273,7 @@ property_get_net_wm_icon(client_t *c)
 void
 property_update_net_wm_icon(client_t *c, xcb_get_property_cookie_t cookie)
 {
-    cairo_surface_t *surface = ewmh_window_icon_get_reply(cookie);
+    cairo_surface_t *surface = ewmh_window_icon_get_reply(cookie, globalconf.preferred_icon_size);
 
     if(!surface)
         return;