round_corners

#!/usr/bin/env ruby

require 'rubygems'
require 'RMagick'

class Magick::Image
    def round_corners( border_radius )
        mask = Magick::Image.new( columns, rows ) { self.background_color = 'black' }

        gc = Magick::Draw.new
        gc.stroke( 'white' ).fill( 'white' )
        gc.roundrectangle( 0, 0, columns-1, rows-1, border_radius, border_radius )
        gc.draw( mask )

        mask.matte = false
        @matte = true

        composite!( mask, Magick::CenterGravity, Magick::CopyOpacityCompositeOp )
    end
end

BORDER_RADIUS = 10

if ARGV[0].nil?
    puts "Input image missing..."
    exit
end

infile = ARGV[0]
outfile = infile.sub( /\.jpg$/, '.png' )

image = Magick::Image.read( infile ).first

image.round_corners( BORDER_RADIUS )

image.write( outfile )
image.destroy!

exit 0