wibox: add support for background image (FS#464)

Signed-off-by: Julien Danjou <julien@danjou.info>

structs.h

@@ -108,6 +108,8 @@ typedef struct
     bool need_update;
     /** Cursor */
     char *cursor;
+    /** Background image */
+    image_t *bg_image;
     /** Button bindings */
     button_array_t buttons;
 } wibox_t;

wibox.c

@@ -861,6 +861,12 @@ luaA_wibox_index(lua_State *L)
       case A_TK_BG:
         luaA_pushcolor(L, &(*wibox)->sw.ctx.bg);
         break;
+      case A_TK_BG_IMAGE:
+        if((*wibox)->bg_image)
+            luaA_image_userdata_new(L, (*wibox)->bg_image);
+        else
+            return 0;
+        break;
       case A_TK_POSITION:
         lua_pushstring(L, position_tostr((*wibox)->position));
         break;
@@ -976,6 +982,23 @@ luaA_wibox_newindex(lua_State *L)
             if(xcolor_init_reply(xcolor_init_unchecked(&(*wibox)->sw.ctx.bg, buf, len)))
                 (*wibox)->need_update = true;
         break;
+      case A_TK_BG_IMAGE:
+        {
+            if(lua_isnil(L, 3))
+            {
+                image_unref(&(*wibox)->bg_image);
+                (*wibox)->bg_image = NULL;
+                (*wibox)->need_update = true;
+            }
+            else
+            {
+                image_t **img = luaA_checkudata(L, 3, "image");
+                image_unref(&(*wibox)->bg_image);
+                (*wibox)->bg_image = image_ref(img);
+                (*wibox)->need_update = true;
+            }
+        }
+        break;
       case A_TK_ALIGN:
         buf = luaL_checklstring(L, 3, &len);
         (*wibox)->align = draw_align_fromstr(buf, len);

widget.c

@@ -270,9 +270,14 @@ widget_render(wibox_t *wibox)
             left += widgets->tab[i].geometry.width;
         }
 
-    /* draw everything! */
+    /* draw background image, only if the background color is not opaque */
+    if(wibox->bg_image && ctx->bg.alpha != 0xffff)
+        draw_image(ctx, 0, 0, 1.0, wibox->bg_image);
+
+    /* draw background color */
     draw_rectangle(ctx, rectangle, 1.0, true, &ctx->bg);
 
+    /* draw everything! */
     for(int i = 0; i < widgets->len; i++)
         if(widgets->tab[i].widget->isvisible)
         {