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module Cairo
class Context
module Blur
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
end
end
end
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