Fixed clock_rings.lua

--[[
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 = {
    {
        -- Edit this table to customise your rings.
        -- You can create more rings simply by adding more elements to settings_table.
        -- "name" is the type of stat to display; you can choose from 'cpu', 'memperc', 'fs_used_perc', 'battery_used_perc'.
        name='time',
        -- "arg" is the argument to the stat type, e.g. if in Conky you would write ${cpu cpu0}, 'cpu0' would be the argument. If you would not use an argument in the Conky variable, use ''.
        arg='%I.%M',
        -- "max" is the maximum value of the ring. If the Conky variable outputs a percentage, use 100.
        max=12,
        -- "bg_colour" is the colour of the base ring.
        bg_colour=0xFFFFFF,
        -- "bg_alpha" is the alpha value of the base ring.
        bg_alpha=0.1,
        -- "fg_colour" is the colour of the indicator part of the ring.
        fg_colour=0xFFFFFF,
        -- "fg_alpha" is the alpha value of the indicator part of the ring.
        fg_alpha=0.5,
        -- "x" and "y" are the x and y coordinates of the centre of the ring, relative to the top left corner of the Conky window.
        x=150, y=150,
        -- "radius" is the radius of the ring.
        radius=135,
        -- "thickness" is the thickness of the ring, centred around the radius.
        thickness=4,
        -- "start_angle" is the starting angle of the ring, in degrees, clockwise from top. Value can be either positive or negative.
        start_angle=0,
        -- "end_angle" is the ending angle of the ring, in degrees, clockwise from top. Value can be either positive or negative, but must be larger than start_angle.
        end_angle=360
    },
    {
        name='time',
        arg='%M.%S',
        max=60,
        bg_colour=0xFFFFFF,
        bg_alpha=0.1,
        fg_colour=0xFFFFFF,
        fg_alpha=0.5,
        x=150, y=150,
        radius=140,
        thickness=4,
        start_angle=0,
        end_angle=360
    },
    {
        name='time',
        arg='%S',
        max=60,
        bg_colour=0xFFFFFF,
        bg_alpha=0.1,
        fg_colour=0xFFFFFF,
        fg_alpha=0.5,
        x=150, y=150,
        radius=145,
        thickness=4,
        start_angle=0,
        end_angle=360
    },
    {
        name='eval',
        arg='1',
        max=1,
        bg_colour=0x000000,
        bg_alpha=0.1,
        fg_colour=0xFFFFFF,
        fg_alpha=0.0,
        x=150, y=150,
        radius=66,
        thickness=130,
        start_angle=0,
        end_angle=360
    },
    {
        name='eval',
        arg='1',
        max=1,
        bg_colour=0xFFFFFF,
        bg_alpha=1.0,
        fg_colour=0xFFFFFF,
        fg_alpha=0.0,
        x=150, y=150,
        radius=1,
        thickness=10,
        start_angle=0,
        end_angle=360
    },
    {
        name='eval',
        arg='1',
        max=1,
        bg_colour=0xFFFFFF,
        bg_alpha=1.0,
        fg_colour=0xFFFFFF,
        fg_alpha=0.0,
        x=85, y=150,
        radius=30,
        thickness=1,
        start_angle=0,
        end_angle=360
    },
    {
        name='eval',
        arg='1',
        max=1,
        bg_colour=0x000000,
        bg_alpha=0.3,
        fg_colour=0xFFFFFF,
        fg_alpha=0.0,
        x=85, y=150,
        radius=15,
        thickness=27,
        start_angle=0,
        end_angle=360
    },
    {
        name='eval',
        arg='1',
        max=1,
        bg_colour=0xFFFFFF,
        bg_alpha=1.0,
        fg_colour=0xFFFFFF,
        fg_alpha=0.0,
        x=85, y=150,
        radius=1,
        thickness=2,
        start_angle=0,
        end_angle=360
    },
    {
        name='eval',
        arg='1',
        max=1,
        bg_colour=0xFFFFFF,
        bg_alpha=1.0,
        fg_colour=0xFFFFFF,
        fg_alpha=0.0,
        x=215, y=150,
        radius=30,
        thickness=1,
        start_angle=0,
        end_angle=360
    },
    {
        name='eval',
        arg='1',
        max=1,
        bg_colour=0x000000,
        bg_alpha=0.3,
        fg_colour=0xFFFFFF,
        fg_alpha=0.0,
        x=215, y=150,
        radius=15,
        thickness=27,
        start_angle=0,
        end_angle=360
    },
    {
        name='eval',
        arg='1',
        max=1,
        bg_colour=0xFFFFFF,
        bg_alpha=1.0,
        fg_colour=0xFFFFFF,
        fg_alpha=0.0,
        x=215, y=150,
        radius=1,
        thickness=2,
        start_angle=0,
        end_angle=360
    },
    {
        name='eval',
        arg='1',
        max=1,
        bg_colour=0xFFFFFF,
        bg_alpha=1.0,
        fg_colour=0xFFFFFF,
        fg_alpha=0.0,
        x=150, y=75,
        radius=25,
        thickness=1,
        start_angle=0,
        end_angle=360
    },
    {
        name='eval',
        arg='1',
        max=1,
        bg_colour=0x000000,
        bg_alpha=0.3,
        fg_colour=0xFFFFFF,
        fg_alpha=0.0,
        x=150, y=75,
        radius=13,
        thickness=22,
        start_angle=0,
        end_angle=360
    },
    {
        name='eval',
        arg='1',
        max=1,
        bg_colour=0xFFFFFF,
        bg_alpha=1.0,
        fg_colour=0xFFFFFF,
        fg_alpha=0.0,
        x=150, y=75,
        radius=1,
        thickness=2,
        start_angle=0,
        end_angle=360
    },
    }

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

clock_r=127

-- "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=150
clock_y=150

-- Colour & alpha of the clock hands

clock_colour=0xFFFFFF
clock_alpha=1

-- Do you want to show the seconds hand?

show_seconds=true

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 draw_clock_hands(cr,xc,yc)
    local secs,mins,hours,secs_arc,mins_arc,hours_arc
    local xh,yh,xm,ym,xs,ys

    secs=os.date("%S")
    mins=os.date("%M")
    hours=os.date("%I")

    secs_arc=(2*math.pi/60)*secs
    mins_arc=(2*math.pi/60)*mins+secs_arc/60
    hours_arc=(2*math.pi/12)*hours+mins_arc/12

    -- Draw hour hand

    xh=xc+0.7*clock_r*math.sin(hours_arc)
    yh=yc-0.7*clock_r*math.cos(hours_arc)
    cairo_move_to(cr,xc,yc)
    cairo_line_to(cr,xh,yh)

    cairo_set_line_cap(cr,CAIRO_LINE_CAP_ROUND)
    cairo_set_line_width(cr,5)
    cairo_set_source_rgba(cr,rgb_to_r_g_b(clock_colour,clock_alpha))
    cairo_stroke(cr)

    -- Draw minute hand

    xm=xc+clock_r*math.sin(mins_arc)
    ym=yc-clock_r*math.cos(mins_arc)
    cairo_move_to(cr,xc,yc)
    cairo_line_to(cr,xm,ym)

    cairo_set_line_width(cr,3)
    cairo_stroke(cr)

    -- Draw seconds hand

    if show_seconds then
        xs=xc+clock_r*math.sin(secs_arc)
        ys=yc-clock_r*math.cos(secs_arc)
        cairo_move_to(cr,xc,yc)
        cairo_line_to(cr,xs,ys)

        cairo_set_line_width(cr,1)
        cairo_stroke(cr)
    end
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

    draw_clock_hands(cr,clock_x,clock_y)
end