From: Chris Pine <cpine@...>
Date: 2004-12-21T21:33:15+09:00
Subject: Re: Programatically resizing photos

Hey, Phil,

I use RMagick and have been very happy with it.  Here's a snippet from 
the program that generates our family picture website.  The "640" code 
just scales the picture to make sure it fits inside a 640x640 box (so 
one dimension is == 640 and the other is <= 640), and the "thumb" code 
makes sure the new image is 160x120, filling with white any area not 
covered by a photo of a different aspect ratio.  (Since there are many 
thumbnails on a page, I wanted them to be all the same size.)  You're 
welcome to check out our site (http://pine.fm), and tell me if you want 
any more of the code.

-----------

def makeImage (fileName, size)
   if !FileTest.exist?('pictures/'+fileName)
     #  TODO:  Error report?
     return 'Cannot find picture "'+fileName+'".'
   end

   altText = if PICTURES[fileName]
     PICTURES[fileName][:desc]
   else
     'This picture needs info.'
   end

   case size

   when 640
     #
     #  Make 640x640 image
     #
     smallFileName = 'pictures_640/640__' + fileName

     if !FileTest.exist?(smallFileName)
       image = Magick::ImageList.new('pictures/'+fileName)
       image = image.change_geometry('640x640') do |cols, rows, img|
         img.resize!(cols, rows)
       end
       image.write(smallFileName) { self.quality = 85 }
     end

     #img(:src=>smallFileName)
     '<img src="'+smallFileName+'" />'

   when :thumb
     #
     #  Make thumbnail image
     #
     smallFileName = 'pictures_thumbs/thumb__' + fileName

     if !FileTest.exist?(smallFileName)
       image = Magick::ImageList.new('pictures/'+fileName)
       thumb = nil
       image.change_geometry('160x120') do |cols, rows, img|
         thumb = img.resize(cols, rows)
       end
       white_bg = Magick::Image.new(160, 120)
       image = white_bg.composite(thumb, Magick::CenterGravity,
                                         Magick::OverCompositeOp)
       image.write(smallFileName) { self.quality = 85 }
     end

     #img(:src=>smallFileName)
     '<img width="160" height="120" src="'+smallFileName+'" />'

   else
     raise 'In "makeImage()"...  Bad Size:  '+size.to_s
   end
end