--[[
Clock Rings by londonali1010 (2009)

This script draws percentage meters as rings, and also draws clock hands if you want! It is fully customisable; all options are described in the script. This script is based off a combination of my clock.lua script and my rings.lua script.

IMPORTANT: if you are using the 'cpu' function, it will cause a segmentation fault if it tries to draw a ring straight away. The if statement near the end of the script uses a delay to make sure that this doesn't happen. It calculates the length of the delay by the number of updates since Conky started. Generally, a value of 5s is long enough, so if you update Conky every 1s, use update_num > 5 in that if statement (the default). If you only update Conky every 2s, you should change it to update_num > 3; conversely if you update Conky every 0.5s, you should use update_num > 10. ALSO, if you change your Conky, is it best to use "killall conky; conky" to update it, otherwise the update_num will not be reset and you will get an error.

To call this script in Conky, use the following (assuming that you save this script to ~/scripts/rings.lua):
	lua_load ~/scripts/clock_rings-v1.1.1.lua
	lua_draw_hook_pre clock_rings

Changelog:
+ v1.1.1 -- Fixed minor bug that caused the script to crash if conky_parse() returns a nil value (20.10.2009)
+ v1.1 -- Added colour option for clock hands (07.10.2009)
+ v1.0 -- Original release (30.09.2009)
]]

settings_table = {
	{
		name='time',
		arg='%I.%M',
		max=12,
		bg_colour=0xffffff,
		bg_alpha=0,
		fg_colour=0xffffff,
		fg_alpha=0.6,
		x=195, y=100,
		radius=60,
		thickness=20,
		start_angle=0,
		end_angle=360
	},
	{
		name='time',
		arg='%M.%S',
		max=60,
		bg_colour=0xffffff,
		bg_alpha=0,
		fg_colour=0xffffff,
		fg_alpha=0.4,
		x=195, y=100,
		radius=78,
		thickness=12,
		start_angle=0,
		end_angle=360
	},
	{
		name='time',
		arg='%S',
		max=60,
		bg_colour=0x000000,
		bg_alpha=0,
		fg_colour=0xffffff,
		fg_alpha=0.2,
		x=195, y=100,
		radius=90,
		thickness=10,
		start_angle=0,
		end_angle=360
	},
}


-- Use these settings to define the origin and extent of your clock.

clock_r=125

-- "clock_x" and "clock_y" are the coordinates of the centre of the clock, in pixels, from the top left of the Conky window.

clock_x=600
clock_y=300

-- Colour & alpha of the clock hands

clock_colour=0xffffff
clock_alpha=1

-- Do you want to show the seconds hand?

require 'cairo'

function rgb_to_r_g_b(colour,alpha)
	return ((colour / 0x10000) % 0x100) / 255., ((colour / 0x100) % 0x100) / 255., (colour % 0x100) / 255., alpha
end

function draw_ring(cr,t,pt)
	local w,h=conky_window.width,conky_window.height

	local xc,yc,ring_r,ring_w,sa,ea=pt['x'],pt['y'],pt['radius'],pt['thickness'],pt['start_angle'],pt['end_angle']
	local bgc, bga, fgc, fga=pt['bg_colour'], pt['bg_alpha'], pt['fg_colour'], pt['fg_alpha']

	local angle_0=sa*(2*math.pi/360)-math.pi/2
	local angle_f=ea*(2*math.pi/360)-math.pi/2
	local t_arc=t*(angle_f-angle_0)

	-- Draw background ring

	cairo_arc(cr,xc,yc,ring_r,angle_0,angle_f)
	cairo_set_source_rgba(cr,rgb_to_r_g_b(bgc,bga))
	cairo_set_line_width(cr,ring_w)
	cairo_stroke(cr)

	-- Draw indicator ring

	cairo_arc(cr,xc,yc,ring_r,angle_0,angle_0+t_arc)
	cairo_set_source_rgba(cr,rgb_to_r_g_b(fgc,fga))
	cairo_stroke(cr)
end


function conky_clock_rings()
	local function setup_rings(cr,pt)
		local str=''
		local value=0

		str=string.format('${%s %s}',pt['name'],pt['arg'])
		str=conky_parse(str)

		value=tonumber(str)
		if value == nil then value = 0 end
		pct=value/pt['max']

		draw_ring(cr,pct,pt)
	end

	-- Check that Conky has been running for at least 5s

	if conky_window==nil then return end
	local cs=cairo_xlib_surface_create(conky_window.display,conky_window.drawable,conky_window.visual, conky_window.width,conky_window.height)

	local cr=cairo_create(cs)	

	local updates=conky_parse('${updates}')
	update_num=tonumber(updates)

	if update_num>5 then
		for i in pairs(settings_table) do
			setup_rings(cr,settings_table[i])
		end
	end
end
