naughty: Add a background widget.

There is some boilerplate code that make using the widget_template
harder when using the raw `wibox.container.background`. This widget
takes care of it.

lib/naughty/container/background.lua

@@ -0,0 +1,99 @@
+----------------------------------------------------------------------------
+--- A notification background.
+--
+-- This widget holds the boilerplate code associated with the notification
+-- background. This includes the color and potentially some other styling
+-- elements such as the shape and border.
+--
+-- * Honor the `beautiful` notification variables.
+-- * React to the `naughty.notification` changes.
+--
+--@DOC_wibox_nwidget_background_simple_EXAMPLE@
+--
+-- Note that this widget is based on the `wibox.container.background`. This is
+-- an implementation detail and may change in the future without prior notice.
+--
+-- @author Emmanuel Lepage Vallee <elv1313@gmail.com>
+-- @copyright 2019 Emmanuel Lepage Vallee
+-- @containermod naughty.widget.background
+-- @see wibox.container.background
+----------------------------------------------------------------------------
+local wbg       = require("wibox.container.background")
+local gtable    = require("gears.table")
+local beautiful = require("beautiful")
+local gshape    = require("gears.shape")
+
+local background = {}
+
+local function update_background(notif, wdg)
+    local bg    = notif.bg           or beautiful.notification_bg
+    local bw    = notif.border_width or beautiful.notification_border_width
+    local bc    = notif.border_color or beautiful.notification_border_color
+
+    -- Always fallback to the rectangle to make sure the border works
+    local shape = notif.shape or
+        beautiful.notification_shape or gshape.rectangle
+
+    wdg:set_bg(bg)
+    wdg:set_shape(shape) -- otherwise there's no borders
+    wdg:set_shape_border_width(bw)
+    wdg:set_shape_border_color(bc)
+end
+
+--- The attached notification.
+-- @property notification
+-- @tparam naughty.notification notification
+
+function background:set_notification(notif)
+    if self._private.notification == notif then return end
+
+    if self._private.notification then
+        self._private.notification:disconnect_signal("poperty::bg",
+            self._private.background_changed_callback)
+        self._private.notification:disconnect_signal("poperty::border_width",
+            self._private.background_changed_callback)
+        self._private.notification:disconnect_signal("poperty::border_color",
+            self._private.background_changed_callback)
+        self._private.notification:disconnect_signal("poperty::shape",
+            self._private.background_changed_callback)
+    end
+
+    update_background(notif, self)
+
+    self._private.notification = notif
+
+    notif:connect_signal("poperty::bg"          , self._private.background_changed_callback)
+    notif:connect_signal("poperty::border_width", self._private.background_changed_callback)
+    notif:connect_signal("poperty::border_color", self._private.background_changed_callback)
+    notif:connect_signal("poperty::shape"       , self._private.background_changed_callback)
+end
+
+--- Create a new naughty.container.background.
+-- @tparam table args
+-- @tparam naughty.notification args.notification The notification.
+-- @constructorfct naughty.container.background
+
+local function new(args)
+    args = args or {}
+
+    local bg = wbg()
+    bg:set_border_strategy("inner")
+
+    gtable.crush(bg, background, true)
+
+    function bg._private.background_changed_callback()
+        update_background(bg._private.notification, bg)
+    end
+
+    if args.notification then
+        bg:set_notification(args.notification)
+    end
+
+    return bg
+end
+
+--@DOC_widget_COMMON@
+
+--@DOC_object_COMMON@
+
+return setmetatable(background, {__call = function(_, ...) return new(...) end})

lib/naughty/container/init.lua

@@ -0,0 +1,9 @@
+---------------------------------------------------------------------------
+-- @author Emmanuel Lepage Vallee <elv1313@gmail.com>
+-- @copyright 2019 Emmanuel Lepage Vallee
+-- @module naughty.container
+---------------------------------------------------------------------------
+
+return {
+    background = require( "naughty.container.background" );
+}

lib/naughty/init.lua

@@ -13,6 +13,8 @@ naughty.action = require("naughty.action")
 naughty.list = require("naughty.list")
 naughty.layout = require("naughty.layout")
 naughty.widget = require("naughty.widget")
+naughty.container = require("naughty.container")
+naughty.action = require("naughty.action")
 naughty.notification = require("naughty.notification")
 
 return naughty