Autoscroll script for the Luakit browser

autoscroll.lua

-- Autoscroll script for luakit (luakit.org).
-- Originally by @mason-larobina
-- (https://gist.github.com/mason-larobina/726550)
--
-- Install instructions:
--  * Add to rc.lua before window spawning code
--  Or
--  * Save to $XDG_CONFIG_HOME/luakit/autoscroll.lua and
--    add `require "autoscroll"` to your rc.lua
----------------------------------------------------------------

local buf, key = lousy.bind.buf, lousy.bind.key
local scroll_step = 1 -- globals.scroll_step -- (too fast)

add_binds("normal", {
			 -- Start autoscroll with a (previously ,a)
			 buf("^a$", function (w) w:set_mode("autoscroll") end),
})

add_binds("autoscroll", {
			 -- Increase scrolling speed
			 key({}, "+", function (w)
					w.autoscroll_timer:stop()
					w.autoscroll_timer.interval = math.max(5, w.autoscroll_timer.interval - 5)
					w.autoscroll_timer:start()
			 end),

			 -- Decrease scrolling speed
			 key({}, "-", function (w)
					w.autoscroll_timer:stop()
					w.autoscroll_timer.interval = w.autoscroll_timer.interval + 5
					w.autoscroll_timer:start()
			 end),

			 -- Default page scroll keybindings,
			 -- so we can still scroll while autoscrolling.
			 key({}, "Page_Down", "Scroll page down.",
				 function (w) w:scroll{ ypagerel =  1.0 } end),

			 key({}, "Page_Up", "Scroll page up.",
				 function (w) w:scroll{ ypagerel = -1.0 } end),
})

new_mode("autoscroll", {
			-- Start autoscroll timer
			enter = function (w)
			   w:set_prompt("-- AUTOSCROLL MODE --")
			   local t = timer{interval=50}
			   t:add_signal("timeout", function ()
							   w:scroll { yrel = scroll_step }
			   end)
			   w.autoscroll_timer = t
			   t:start()
			end,

			-- Stop autoscroll timer
			leave = function (w)
			   if w.autoscroll_timer then
				  w.autoscroll_timer:stop()
				  w.autoscroll_timer = nil
			   end
			end,
})