lain/widgets/contrib/redshift.lua

--[[
                                                        
     Licensed under GNU General Public License v2       
      * (c) 2014, blueluke <http://github.com/blueluke> 
                                                        
--]]

local awful        = require("awful")
local os           = os
local spawn        = awful.util.spawn_with_shell

local setmetatable = setmetatable

-- Redshift
-- lain.widgets.contrib.redshift
local redshift = {}

local attached    = false           -- true if attached to a widget
local active      = false           -- true if redshift is active
local running     = false           -- true if redshift was initialized
local update_fnct = function() end  -- Function that is run each time redshift is toggled. See redshift:attach().

local function init()
    -- As there is no way to determine if redshift was previously
    -- toggled off (i.e Awesome on-the-fly restart), kill redshift to make sure
    os.execute("pkill redshift")
    -- Remove existing color adjustment
    spawn("redshift -x")
    -- (Re)start redshift
    spawn("redshift")
    running = true
    active = true
end

function redshift:toggle()
    if running then
        -- Sending -USR1 toggles redshift (See project website)
        os.execute("pkill -USR1 redshift")
        active = not active
    else
        init()
    end
    update_fnct()
end

function redshift:off()
    if running and active then
        redshift:toggle()
    end
end

function redshift:on()
    if not active then
        redshift:toggle()
    end
end

function redshift:is_active()
    return active
end

-- Attach to a widget
-- Provides a button which toggles redshift on/off on click
-- @param widget:  Widget to attach to.
-- @param fnct:    Function to be run each time redshift is toggled (optional).
--                 Use it to update widget text or icons on status change.
function redshift:attach(widget, fnct)
    update_fnct  = fnct or function() end
    if not attached then
        init()
        attached = true
        update_fnct()
    end
    widget:buttons(awful.util.table.join( awful.button({}, 1, function () redshift:toggle() end) ))
end

return setmetatable(redshift, { _call = function(_, ...) return create(...) end })