Dimension

Lightweight image resizing for Ruby, either with vips, imlib2 or ImageMagick.

  require 'dimension'

  thumb = Dimension.open('tux.png')
  thumb.generate('100x100') # => { :width => 100, :height => 100 }
  thumb.save('resized.png')

Or generate and write file automatically.

  thumb = Dimension.open('tux.png')
  thumb.generate!('100x300!') # will write file as 'tux-100x300.png'

In memory processing

Yes sir, we have it.

  thumb = Dimension.open(params[:file])
  thumb.generate('200x300#')
  thumb.image_data

You can also pass a block, which will ensure the original image is closed after processing.

  get '/resize/:file' do
    thumb = Dimension.open(params[:file])
    thumb.generate('200x300@') do
      thumb.to_response
    end
  end

Installation

For vips backend:

# install library
apt install libvips42
# then, the ruby bindings
gem install ruby-vips
# and in case you don't get a libvips.so symlink
sudo ln -s /usr/lib/x86_64-linux-gnu/libvips.so.42 /usr/lib/x86_64-linux-gnu/libvips.so

For imlib2 backend:

# install deps
sudo apt install libimlib2-dev
# clone repo
git clone https://github.com/pepabo/imlib2-ruby
cd imlib2-ruby
# build/install
ruby extconf.rb
make
make install
# and clean up
cd ..
rm -Rf imlib2-ruby

For ImageMagick, there's no gem required. Just make sure the binaries (identify, convert) are in place:

sudo apt install imagemagick

TODO

• Support for N/S/W/E gravities.
• Tests (e.g. ensure geometry calculation works equally across backends).

Related

• Dragonfly gem. This is where the original inspiration came from.

Author

Written by Tomás Pollak.

Copyright

(c) Fork, Ltd. MIT Licensed.