Add Graphics Magick support

[brodock]

Graphics Magick is in some way similar to ImageMagick (does have a compatibility layer) but may differ in many other ways. The one that makes this propose a win, is that Graphics Magick is made with performance in mind.

On official website, there are a list of advantages: Here are some reasons to prefer GraphicsMagick over ImageMagick:

• GM is more efficient (see the benchmarks) so it gets the job done faster using fewer resources.
• GM is much smaller and tighter (3-5X smaller installation footprint).
• GM is used to process billions of files at the world's largest photo sites (e.g. Flickr and Etsy).
• GM does not does not conflict with other installed software.
• GM suffers from fewer security issues and exploits.
• GM valgrind's 100% clean (memcheck and helgrind).
• GM comes with a comprehensive manual page.
• GM provides API and ABI stability and managed releases that you can count on.
• GM provides detailed yet comprehensible ChangeLog and NEWS files.
• GM is available for free, and may be used to support both open and proprietary applications.
• GM is distributed under an X11-style license ("MIT License"), approved by the Open Source Initiative, recommended for use by the OSSCC, and compatible with the GNU GPL.
• GM source code is managed in Mercurial, a distributed source control management tool which supports management of local changes.
• GM developers contribute to other free projects for the public good.

source: http://www.graphicsmagick.org/

So, by that in mind, I think that is a cood candidate, and I also have something in mind that can help make both works: https://github.com/probablycorey/mini_magick

I don't know if mini_magick have all the necessary APIs but, it can be extended so to cover all needs that paperclip have. Also it's a good idea to separate the "graphics logic" from "paperclips logic"

[jyurek]

While you make good points, there's nothing stopping you from using GM with paperclip now.

[mike-burns]

@brodock you can make a paperclip-graphicsmagick gem that interacts with Paperclip. See https://github.com/thoughtbot/paperclip-thumbnailer for an example of how to write a processor; you can even leverage that gem to build your processor.

Let us know how it goes!

[mulderp]

Hi Mike,

I just put a small processor for graphicsmagick together: https://github.com/mulderp/paperclip-gmagick

I also released 0.0.1 of paperclip-graphicsmagick (Only resizing is supported right now, and it's more or less extracted from the thumbnail processor)

Eventually helpful for others.

[LYY]

@mulderp I switched to graphicsmagick recently, mini_magick can support both im and gm, but paperclip doesn't.

your work is very helpful for me, thank you!

[mulderp]

Thanks! Happy to hear. If I remember correctly, it was rather a quick hack, if you find bugs/issues just file a bug or send a PR!

[w-4luar]

Maybe a bit late, but the following solution works right for me and is extremely easy to implement:

    module MyNamespace
      module Paperclip
        module Helpers
          ImageMagick_commands = [
              "animate",
              "batch",
              "benchmark",
              "compare",
              "composite",
              "conjure",
              "convert",
              "display",
              "identify",
              "import",
              "mogrify",
              "montage"
          ]

          def run(cmd, arguments = "", interpolation_values = {}, local_options = {})

            if ImageMagick_commands.include?(cmd.to_s)
              arguments.prepend(cmd + ' ')
              cmd = 'gm'
            end

            super
          end
        end
      end
    end

    module Paperclip
      extend MyNamespace::Paperclip::Helpers
    end