Merge pull request #780 from psychon/screen-add-signal

Add screen add signal

awesome.c

@@ -643,9 +643,6 @@ main(int argc, char **argv)
     /* init atom cache */
     atoms_init(globalconf.connection);
 
-    /* init screens information */
-    screen_scan();
-
     /* do this only for real screen */
     ewmh_init();
     systray_init();
@@ -702,6 +699,9 @@ main(int argc, char **argv)
 
     xdgWipeHandle(&xdg);
 
+    /* init screens information */
+    screen_scan();
+
     /* scan existing windows */
     scan(tree_c);
 

awesomerc.lua

@@ -91,19 +91,19 @@ end
 
 -- {{{ Wallpaper
 if beautiful.wallpaper then
-    for s in screen do
+    gears.screen.connect_for_each_screen(function(s)
         gears.wallpaper.maximized(beautiful.wallpaper, s, true)
-    end
+    end)
 end
 -- }}}
 
 -- {{{ Tags
 -- Define a tag table which hold all screen tags.
 tags = {}
-for s in screen do
+gears.screen.connect_for_each_screen(function(s)
     -- Each screen has its own tag table.
     tags[s] = awful.tag({ 1, 2, 3, 4, 5, 6, 7, 8, 9 }, s, awful.layout.layouts[1])
-end
+end)
 -- }}}
 
 -- {{{ Menu
@@ -175,7 +175,7 @@ mytasklist.buttons = awful.util.table.join(
                                               awful.client.focus.byidx(-1)
                                           end))
 
-for s in screen do
+gears.screen.connect_for_each_screen(function(s)
     -- Create a promptbox for each screen
     mypromptbox[s] = awful.widget.prompt()
     -- Create an imagebox widget which will contains an icon indicating which layout we're using.
@@ -213,7 +213,7 @@ for s in screen do
             mylayoutbox[s],
         },
     }
-end
+end)
 -- }}}
 
 -- {{{ Mouse bindings

lib/gears/init.lua

@@ -18,6 +18,7 @@ return
     matrix = require("gears.matrix");
     shape = require("gears.shape");
     protected_call = require("gears.protected_call");
+    screen = require("gears.screen");
 }
 
 -- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80

lib/gears/screen.lua

@@ -0,0 +1,29 @@
+---------------------------------------------------------------------------
+-- @author Uli Schlachter
+-- @copyright 2016 Uli Schlachter
+-- @release @AWESOME_VERSION@
+-- @classmod gears.screen
+---------------------------------------------------------------------------
+
+local screen = screen
+
+local module = {}
+
+--- Call a function for each existing and created-in-the-future screen.
+-- @tparam function func The function to call.
+function module.connect_for_each_screen(func)
+    for s in screen do
+        func(s)
+    end
+    screen.connect_signal("added", func)
+end
+
+--- Undo the effect of connect_for_each_screen.
+-- @tparam function func The function that should no longer be called.
+function module.disconnect_for_each_screen(func)
+    screen.disconnect_signal("added", func)
+end
+
+return module
+
+-- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80

lib/gears/wallpaper.lua

@@ -13,20 +13,12 @@ local timer = require("gears.timer")
 local wallpaper = { mt = {} }
 
 -- The size of the root window
-local root_geom
-do
-    local geom = screen[1].geometry
-    root_geom = {
-        x = 0, y = 0,
-        width = geom.x + geom.width,
-        height = geom.y + geom.height
-    }
-    for s in screen do
-        local g = screen[s].geometry
+local root_geom = { x = 0, y = 0, width = 0, height = 0 }
+require("gears.screen").connect_for_each_screen(function(s)
+    local g = s.geometry
     root_geom.width = math.max(root_geom.width, g.x + g.width)
     root_geom.height = math.max(root_geom.height, g.y + g.height)
-    end
-end
+end)
 
 -- A cairo surface that we still want to set as the wallpaper
 local pending_wallpaper = nil

lib/naughty/core.lua

@@ -143,8 +143,8 @@ local suspended = false
 -- @field id Unique notification id based on a counter
 -- @table notifications
 naughty.notifications = { suspended = { } }
-for s in capi.screen do
-    naughty.notifications[get_screen(s)] = {
+require("gears.screen").connect_for_each_screen(function(s)
+    naughty.notifications[s] = {
         top_left = {},
         top_middle = {},
         top_right = {},
@@ -152,7 +152,7 @@ for s in capi.screen do
         bottom_middle = {},
         bottom_right = {},
     }
-end
+end)
 
 --- Notification state
 function naughty.is_suspended()

objects/screen.c

@@ -145,8 +145,12 @@ screen_add(lua_State *L, int sidx)
                 return;
             }
 
+    sidx = luaA_absindex(L, sidx);
+    lua_pushvalue(L, sidx);
     luaA_object_ref(L, sidx);
     screen_array_append(&globalconf.screens, new_screen);
+    luaA_object_emit_signal(L, -1, "added", 0);
+    lua_pop(L, 1);
 }
 
 static bool
@@ -755,6 +759,11 @@ screen_class_setup(lua_State *L)
      * @signal primary_changed
      */
     signal_add(&screen_class.signals, "primary_changed");
+    /**
+     * This signal is emitted when a new screen is added to the current setup.
+     * @signal added
+     */
+    signal_add(&screen_class.signals, "added");
 }
 
 // vim: filetype=c:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80