Generate colors that are between a start and end color. It's a gradient. Useful to pass to a Graphite graph as "colorList".

colors.rb

# Create a gradient color list.
# Shamelessly ported from php code at http://www.herethere.net/~samson/php/color_gradient

begin_color = 0xfffde3
end_color = 0xffb715
samples = 30

def interpolate(b, e, step, max)
  if b < e
    (((e - b) * (step / max.to_f)) + b).to_i
  else
    (((b - e) * (1 - step / max.to_f)) + e).to_i
  end
end

def generate(b, e, steps)
  r0 = (b & 0xff0000) >> 16
  g0 = (b & 0x00ff00) >> 8
  b0 = (b & 0x0000ff) >> 0

  r1 = (e & 0xff0000) >> 16
  g1 = (e & 0x00ff00) >> 8
  b1 = (e & 0x0000ff) >> 0
  (0..steps).map do |step|
    r = interpolate(r0, r1, step, steps)
    g = interpolate(g0, g1, step, steps)
    b = interpolate(b0, b1, step, steps)
    (r << 8 | g) << 8 | b
  end
end

generate(begin_color, end_color, samples).each do |c|
  hex = "%06X" % c
  print "#{hex},"
end
puts