Well Rounded Images for Rails with acts_as_attachment

In today’s world of Web 2.0, with rounded corners on everything, it seems a shame to have tacky square corner images uploaded by your customers. Luckily, those of us in the rails community have acts_as_attachment to assist with the upload. It’s really extensible, and allows you to have access to (most of) the ImageMagick functions underneath.

A recent personal project of mine required image upload, and creation of thumbnails, etc. acts_as_attachment fit the bill nicely, with the exception of square corners. I conjured up a snippet of code to trim the corners with RMagick, and voila! Round Corners on my images. Code follows. Note: due to MSIE braindamaged handling of PNG, this code creates GIF images (recently unencumbered by patents).

require 'RMagick'
include Magick
 
class SessionImage < ActiveRecord::Base
 
  belongs_to :user
 
  acts_as_attachment (:storage => :file_system,
                      :thumbnails => {'large' => '320',
                                      'medium' =>  '120',
                                      'thumb' => '90'},
                      :max_size => 5.megabytes,
                      :content_type => :image)
  before_thumbnail_saved do |record, thumb|
    img = Magick::Image::from_blob(thumb.attachment_data).first
    cols = img.columns
    rows = img.rows
    # Make the background green, so we know if something went wrong
    draw = Draw.new {self.background_color = 'green'}
    # Draw a round rectangle into the "Draw" object
    draw.roundrectangle(0, 0, cols-1, rows-1, 10, 10)
    # Draw the image froim before into the Draw Object
    draw.composite(0,0,0, 0,img,InCompositeOp)
    # Have to create a new image for some reason - GIF it for MSIE
    newimg = Magick::Image.new(cols,rows)
        {background_color = 'none', self.format = 'gif'}
    # This is the money line - puts the round corner image into our new image
    draw.draw(newimg)
    newimg['comment'] = 'Round Corners'
    # Replace the data that was sent to us.
    thumb.attachment_data = newimg
  end
 
  validates_as_attachment
 
 
# This is required, because we change whatever image type
# that was sent in to GIF
  def thumbnail_name_for(thumbnail = nil)
    return filename unless thumbnail
    basename, ext = filename.split '.'
    "#{basename}_#{thumbnail}.gif"
  end
 
end

Enjoy!

dhw

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