Gradient

From awesome

Contents 1 Introduction 2 Gradient 3 dec2hex 4 Example 5 Graph

[edit] Introduction

Our eyes can process graphical data much faster then numerical. The following two functions allow you to convert numerical data into a hexadecimal colorgradient given three variables {min, val, max} with the relation: min <= val <= max. The actual color gradient looks like this:

[edit] Gradient

The following function converts a value between min, max into a hexadecimal color.

function gradient(min, max, val)
  if (val > max) then val = max end
  if (val < min) then val = min end

  local v = val - min
  local d = (max - min) * 0.5
  local r, g

  if (v <= d) then
    r = (255 * v) / d
    g = 255
  else
    r = 255
    g = 255 - (255 * (v-d)) / (max - min - d)
  end

  return "#"..dec2hex(tostring(r))..dec2hex(tostring(g)).."00"
end

[edit] dec2hex

The dec2hex function maps decimals to hexadecimals.

function dec2hex(s)
  s = string.format("%02x", s)
  return s
end

[edit] Example

The following example shows my cores temperature and usage in a color gradient using wicked.

-- {{{ CPU USAGE
cputextwidget = widget({
	type = 'textbox',
	name = 'cputextwidget',
	align = 'right'
})

wicked.register(cputextwidget, 'cpu', function(widget, args)
	cpuinfo = title("CPU")
	cpuinfo = color(cpuinfo..'['..args[2]..'% '..cputemp(0)..'°C]  ', gradient(0, 100, tonumber(args[2])))
	cpuinfo = color(cpuinfo..'['..args[3]..'% '..cputemp(1)..'°C]  ', gradient(0, 100, tonumber(args[3])))
	cpuinfo = color(cpuinfo..'['..args[4]..'% '..cputemp(2)..'°C]  ', gradient(0, 100, tonumber(args[4])))
	cpuinfo = color(cpuinfo..'['..args[5]..'% '..cputemp(3)..'°C]  ', gradient(0, 100, tonumber(args[5])))
	return cpuinfo
end, 1, nil, 2)
-- }}}

[edit] Graph

This is what the actual function does on numerical data from [0..100] for the red and green channels (blue remains 0).