Merge pull request #2507 from Elv13/xmas_2k18_1

New theme API groundwork

awesomerc.lua

@@ -163,7 +163,7 @@ local tasklist_buttons = gears.table.join(
                                           end))
 
 -- @DOC_WALLPAPER@
-local function set_wallpaper(s)
+screen.connect_signal("request::wallpaper", function(s)
     -- Wallpaper
     if beautiful.wallpaper then
         local wallpaper = beautiful.wallpaper
@@ -173,16 +173,10 @@ local function set_wallpaper(s)
         end
         gears.wallpaper.maximized(wallpaper, s, true)
     end
-end
-
--- Re-set wallpaper when a screen's geometry changes (e.g. different resolution)
-screen.connect_signal("property::geometry", set_wallpaper)
+end)
 
 -- @DOC_FOR_EACH_SCREEN@
-awful.screen.connect_for_each_screen(function(s)
-    -- Wallpaper
-    set_wallpaper(s)
-
+screen.connect_signal("request::desktop_decoration", function(s)
     -- Each screen has its own tag table.
     awful.tag({ "1", "2", "3", "4", "5", "6", "7", "8", "9" }, s, awful.layout.layouts[1])
 

common/luaclass.c

@@ -22,6 +22,8 @@
 #include "common/luaclass.h"
 #include "common/luaobject.h"
 
+#define CONNECTED_SUFFIX "::connected"
+
 struct lua_class_property
 {
     /** Name of the property */
@@ -300,6 +302,24 @@ luaA_class_connect_signal_from_stack(lua_State *L, lua_class_t *lua_class,
                                      const char *name, int ud)
 {
     luaA_checkfunction(L, ud);
+
+    /* Duplicate the function in the stack */
+    lua_pushvalue(L, ud);
+
+    char *buf = p_alloca(char, a_strlen(name) + a_strlen(CONNECTED_SUFFIX) + 1);
+
+    /* Create a new signal to notify there is a global connection. */
+    sprintf(buf, "%s%s", name, CONNECTED_SUFFIX);
+
+    /* Emit a signal to notify Lua of the global connection.
+     *
+     * This can useful during initialization where the signal needs to be
+     * artificially emitted for existing objects as soon as something connects
+     * to it
+     */
+    luaA_class_emit_signal(L, lua_class, buf, 1);
+
+    /* Register the signal to the CAPI list */
     signal_connect(&lua_class->signals, name, luaA_object_ref(L, ud));
 }
 
@@ -512,4 +532,6 @@ luaA_class_new(lua_State *L, lua_class_t *lua_class)
     return 1;
 }
 
+#undef CONNECTED_SUFFIX
+
 // vim: filetype=c:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80

docs/89-NEWS.md

@@ -14,6 +14,9 @@ This document was last updated at commit v4.3-197-g9085ed631.
 
 ## New features
 
+* `awful.screen` now has a `request::wallpaper` and a
+  `request::desktop_decoration` signal. They make some workflow implementation
+  cleaner.
 * Lua code can interact with the selection contents via the new
   `selection.acquire`, `selection.getter`, and `selection.watcher` objects
 * Pending delayed calls (`gears.timer.delayed_call`) can be dispatched via

lib/awful/screen.lua

@@ -602,6 +602,54 @@ function screen.object.set_dpi(s, dpi)
     s.data.dpi = dpi
 end
 
+--- Emitted when a new screen is added.
+--
+-- The handler(s) of this signal are responsible of adding elements such as
+-- bars, docks or other elements to a screen. The signal is emitted when a
+-- screen is added, including during startup.
+--
+-- The only default implementation is the one provided by `rc.lua`.
+--
+-- @signal request::desktop_decoration
+-- @tparam screen s The screen object.
+
+--- Emitted when a new screen needs a wallpaper.
+--
+-- The handler(s) of this signal are responsible to set the wallpaper. The
+-- signal is emitted when a screen is added (including at startup), when its
+-- DPI changes or when its geometry changes.
+--
+-- The only default implementation is the one provided by `rc.lua`.
+--
+-- @signal request::wallpaper
+-- @tparam screen s The screen object.
+
+-- Set the wallpaper(s) and create the bar(s) for new screens
+capi.screen.connect_signal("added", function(s)
+    s:emit_signal("request::desktop_decoration")
+    s:emit_signal("request::wallpaper")
+end)
+
+-- Resize the wallpaper(s)
+for _, prop in ipairs {"geometry", "dpi" } do
+    capi.screen.connect_signal("property::"..prop, function(s)
+        s:emit_signal("request::wallpaper")
+    end)
+end
+
+-- Create the bar for existing screens when an handler is added
+capi.screen.connect_signal("request::desktop_decoration::connected", function(new_handler)
+    for s in capi.screen do
+        new_handler(s)
+    end
+end)
+
+-- Set the wallpaper when an handler is added.
+capi.screen.connect_signal("request::wallpaper::connected", function(new_handler)
+    for s in capi.screen do
+        new_handler(s)
+    end
+end)
 
 --- When the tag history changed.
 -- @signal tag::history::update

spec/awful/screen_spec.lua

@@ -6,6 +6,7 @@
 local fake_screens = {}
 
 _G.screen = setmetatable({
+    connect_signal = function() end,
     set_index_miss_handler = function() end,
     set_newindex_miss_handler = function() end,
 }, {