Resize image example on radiant CMS on ubuntu with back_door

I assume this is the same command as doing 开发者_运维技巧it in Sinatra.

I want to server-side resize user-uploaded images to a standard width using back_door. I assume RMijick is the way to go - but I'd just like a code sample to achieve this.

I want to know whether it is a better pattern to resize and then cache with rack-pagespeed, or just check to see if the image requested has already been resized and skip the operation.

Note: I'm assuming you've installed and configured radiant and the back_door extension.

So start off with the ubuntu install:

apt-get install libmagick9-dev

Then the gem install

gem install rmagick

Then validate the gem version:

irb -rubygems -r RMagick
irb(main):001:0> puts Magick::Long_version

Then reload apache

/etc/init.d/apache2 reload

Then in your page do:

<r:ruby>
require 'RMagick'
if File.exists?("/var/www/grub/public/page_attachments/0000/0010/MexicanBeefSalad190.jpg")
  #"file exists"
else
  img = Magick::Image.read "/var/www/grub/public/page_attachments/0000/0010/MexicanBeefSalad.jpg"
  img[0].change_geometry('190x190') { |cols, rows, img2|
    img2.scale!(cols, rows)
  }
  img[0].write ("/var/www/grub/public/page_attachments/0000/0010/MexicanBeefSalad190.jpg")
  #"not exists"
end
</r:ruby>