Speech bubble PNG icon generator - mimicks the Facebook for iPhone comments toolbar button

bubble.rb

require 'rubygems'
require 'Rmagick'

include Magick

# In pixels
SQUARE_SIZE = 20
CORNER = 2
SPIKE_OFFSET, SPIKE_WIDTH, SPIKE_HEIGHT = 7, 4, 6

bubble = Image.new(SQUARE_SIZE, SQUARE_SIZE + SPIKE_HEIGHT) do
  self.background_color = 'transparent'
end

gc = Draw.new

# Rounded square
gc.fill('white')
gc.fill_opacity(1)
gc.roundrectangle(0, 0, SQUARE_SIZE - 1, SQUARE_SIZE - 1, CORNER, CORNER)

# Triangle
gc.polygon(SPIKE_OFFSET, SQUARE_SIZE,
           SPIKE_OFFSET + SPIKE_WIDTH, SQUARE_SIZE,
           SPIKE_OFFSET, SQUARE_SIZE + SPIKE_HEIGHT - 1)

gc.draw(bubble)
bubble.write("bubble.png")