From: Eddie Du <lists@...>
Date: 2012-09-06T03:47:15+09:00
Subject: Transparency not working on my Mac. Help!

Here's some code to overlay a transparent square over a blue background
- at least I think it should do this.

I'm on OSX 10.7.3, ruby 1.9.3p125, RMagick 2.13.1, ImageMagick 6.7.5-7

Code:
###########################
require 'RMagick'

bg = Magick::Image.new(400, 400) {
  self.background_color = 'blue'
}

sq = Magick::Image.new(200, 200) {
  self.background_color = 'none'
}

bg.composite!(sq, 0, 0, Magick::OverCompositeOp)

bg.write('out.png')
###########################

Here's my output (The square is not transparent, it's completely black):
http://i.imgur.com/TKVHr.png

Does this happen to you? Any idea what's going on?

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