From: Timothy Hunter <TimHunter@...>
Date: 2006-08-03T06:17:16+09:00
Subject: Can't convert String into Integer (TypeError)

Okay, I'm stumped. I've been looking at this program off-and-on for 3 
days now and I can't understand why it's failing like it does. It's 
*supposed* to fail, but not the way it does.

The Image#dissolve method takes 2 arguments, an Image object and a 
percentage. The percentage argument can be specified either as a number 
between 0.0 and 1.0, or as a string in the form "NNN%", like "50%" for 
example. In this test I'm passing "1x0%" as the percentage, which is 
clearly incorrect. I expect dissolve to raise an ArgumentError exception 
with the message "expected percentage, got `1x0%'". What actually 
happens is that I get

/Users/timothyhunter/Temporary/bug.rb:22:in `raise': can't convert 
String into Integer (TypeError)
        from /Users/timothyhunter/Temporary/bug.rb:22:in `dissolve'
        from /Users/timothyhunter/Temporary/bug.rb:43

Line 22 is the "raise" statement.

What am I missing?

require 'RMagick'

module Magick
    class Image
       
        # Similar to `composite self -dissolve pct overlay'
        # Returns composited result
        def dissolve(overlay, pct)
            begin
                # Clamp to 0 <= pct <= 1
                pct = [1.0, Float(pct)].min
                pct = [0.0, pct].max
                # Convert to 0 <= pct <= 100
                pct = (pct * 100.0).to_i
            rescue
                m = pct.to_s.match(/\A(\d+)%\z/)
                if m
                    # Clamp to 0 <= pct <= 100
                    pct = [100, m[1].to_i].min
                    pct = [0, pct].max
                else                   
                    raise ArgumentError, "expected percentage, got `#{pct}'"
                end
            end
           
            temp = overlay.geometry
            begin
                overlay.geometry = pct.to_s
                res = composite(overlay, 0, 0, Magick::DissolveCompositeOp)
            ensure
                overlay.geometry = temp
            end
            return res
        end
       
    end
end

# composite Flower_Hat.jpg -dissolve 90 Violin.jpg
bgnd = Magick::Image.read('Flower_Hat.jpg').first
overlay = Magick::Image.read('Violin.jpg').first

bgnd.dissolve(overlay, '1x0%').display