From: Tim Blair <tblair@...>
Date: 2006-04-06T20:56:37+09:00
Subject: Re: Creating images from pixel data (RMagick?)


Paul,

> If that won't work, Imlib2-Ruby may be fast enough to do
> what you want

Thanks for that.  Unfortunately we're looking for a cross-platform
solution so using imlib2 appears to be out of the running.

However, I have managed to speed up the generation a lot by using the
Rmagick Image#store_pixels method instead of Draw#fill - we now have the
512x384 image generating in <5 seconds which is OK for what we're doing
(at least at the moment!).  We're now limited by the speed at which the
flash player can glean the pixel data, rather than how fast the image
can be generated.  Code below.

Thanks again for the help.  Maybe your imlib2 will come in useful when
someone turns around and says "surely we can do that sooooo much
quicker?!" :)

Cheers,

Tim.


require 'RMagick'
class RippedImage
  def initialize (job_id, width, height)
    @job_id = job_id.to_s;
    @width = width.to_i;
    @height = height.to_i;
    @canvas = Magick::Image.new(@width, @height)
    @pixels = []
  end
  def draw (c)
    # the colour is a 6 digit hex char which needs to
    # be converted to numeric values for RGB
    col = []
    c.scan(/../).each { |bit| col << bit.hex }
    @pixels << Magick::Pixel.new(col[0], col[1], col[2], 0)
  end
  def finalize (type="gif")
    @canvas.store_pixels(0, 0, @width, @height, @pixels)
    @canvas.write("#{@job_id}.#{type}")
  end
end

x = 512
y = 384
colours = ["ff0000", "00ff00", "0000ff"]
img = RippedImage.new(1, x, y)
(x*y).times do
  img.draw(colours[rand(colours.length)])
end
img.finalize

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