Papercrop

An easy extension for Paperclip to crop your image uploads using jCrop.

Installation

Include papercrop in your Gemfile or install it by hand

gem install papercrop

You need to add the required files in your assets...

In your application.js

//= require jquery
//= require jquery.jcrop
//= require papercrop

In your application.css

*= require jquery.jcrop

Using Papercrop

You are a few steps away to start cropping attachments. Let's start with the model, a user with avatar:

has_attached_file :avatar, :styles => {:thumb => '50x50', :medium => '100x100'}
crop_attached_file :avatar

By default, the crop area and the preview box will have an aspect ratio of 1:1. You can modify that by passing a new aspect.

crop_attached_file :snapshot, :aspect => "16:9"

On the controller you can render a view after user creation, create a simple crop action, etc... whatever you like the most. Inside the form of a persisted user:

<%= form_for @user do |f| %>
  <%= f.cropbox :avatar %>
  <%= f.crop_preview :avatar %>
  <%= f.submit 'Save' %>
<% end %>

Both helpers accept a :width option to customize their dimensions. The preview box has width 100 by default but the cropbox is unlimited in size (takes the original image width), so setting the cropbox width is interesting to avoid layout breaks with huge images. 

<%= form_for @user do |f| %>
  <%= f.cropbox :avatar, :width => 500 %>
  <%= f.crop_preview :avatar, :width => 150 %>
  <%= f.submit 'Save' %>
<% end %>

Regardless of the width, the preview box and the cropping area will have the aspect ratio defined in the model (1:1 by default)

If you're rendering it on ajax ensure to call init_papercrop() in js after loading the crop form to make things work properly.

Running the Tests

We are using a dummy application to handle some of our test cases. You can find this in the /test_app directory and should be able to run this as a regular Rails 4 app (using the rails s command) if you're interested in taking a look. You may need to create the mock database for the test_app before your tests will start to pass. This means you need to run rake db:create db:migrate db:test:prepare from within the test_app directory.

In order to fully test our gem, we needed to use Selenium. Getting this setup is beyond the scope of this Readme.

Once you have everything setup, you should be able bundle exec rake from the root directory have everything run. If you've installed Selenium properly, you should see an automated instance of your browser (eg. Firefox) pop up and run through some of the integration tests.

That's all!

Credits and resources