Add option to show additional notification

README.md

@@ -66,15 +66,46 @@ will resize them to fit in the available space. This means that you can switch
 your icon theme, for example using `lxappearance`, and update the widget by
 restarting AwesomeWM.
 
+## GUI client
+
 You can specify a GUI client to be launched when the widget is right-clicked.
 This can be done by changing the `gui_client` field of the widget. The default
 is to have no client. For example, you could use the [XFCE4 Power
 Manager](http://goodies.xfce.org/projects/applications/xfce4-power-manager) or
 the [GNOME one](https://projects.gnome.org/gnome-power-manager/).
 
+## Critical Battery Percentage
 You can set the critical battery percentage at which a warning will be
 displayed using the `critical_percentage` property (defaults to `5`).
 
+## Additional Warning Notification
+
+The `warning_config` property holds a table used to configure an additional
+warning notification at a custom percentage. This is disabled by default.
+
+It **must** contain the following properties:
+
+- `percentage`: a numeric value used to trigger the notification
+- `preset`: a [naughty preset
+  table](https://awesomewm.org/doc/api/libraries/naughty.html#config.presets)
+
+For example, one could ad a warning with a black foreground color and yellow
+background color once the battery discharges below 15% as follows:
+
+``` lua
+widget.warning_config = {
+  percentage = 15,
+  preset = {
+    bg = "#FFFF00",
+    fg = "#000000",
+  },
+}
+```
+
+You can change about anything on the notification (shape, position, opacity,
+etc.). For more details a look at the [naughty.notify
+documentation](https://awesomewm.org/doc/api/libraries/naughty.html#notify).
+
 # Mouse controls
 
 When the widget is focused:

power_widget.lua

@@ -151,6 +151,13 @@ local function update(widget)
     should_warn_critical(widget),
     naughty.config.presets.critical
   )
+
+  maybe_warn(
+    widget,
+    get_percentage(widget) <= widget.warning_config.percentage,
+    widget.warning_config.preset
+  )
+
 end
 
 local function init(widget)
@@ -167,6 +174,12 @@ local function init(widget)
   widget.gui_client = ni
   widget.critical_percentage = 5
 
+  widget.warning_config = {
+    percentage = -1,            -- disabled by default
+    -- https://awesomewm.org/doc/api/libraries/naughty.html#config.presets
+    preset = naughty.config.presets.normal,
+  }
+
   update(widget)
 
   widget:buttons(awful.util.table.join(