module Cairo::Context::Blur

Public Instance Methods

pseudo_blur(radius=3, &block) click to toggle source
# File lib/cairo/context/blur.rb, line 4
def pseudo_blur(radius=3, &block)
  raise ArgumentError, "should specify block" if block.nil?
  pattern = push_group(Cairo::CONTENT_COLOR_ALPHA, false, &block)

  save do
    set_source(pattern)
    paint(0.5)
  end

  1.step(radius, 1) do |i|
    opacity = 0.075 - 0.005 * i
    next if opacity <= 0
    5.downto(1) do |ratio|
      r = i / ratio.to_f
      r_13 = r / 3.0
      r_23 = 2 * r_13
      [
       [-r, 0],
       [-r_23, r_23],
       [-r_23, r_13],
       [0, r],
       [r_13, r_23],
       [r_23, r_23],
       [r, 0],
       [r_23, -r_13],
       [r_23, -r_23],
       [0, -r],
       [-r_13, -r_23],
       [-r_23, -r_23],
      ].each do |x, y|
        save do
          translate(x, y)
          set_source(pattern)
          paint(opacity)
        end
      end
    end
  end
end