app/views/user_profiles/crop.html.erb
<% title "Crop Photo" %>
<%= image_tag @user_profile.photo.url(:original), id: "cropbox" %>
<a href="#" class="show_hide">Show/hide crop dimensions</a>
<%= form_for @user_profile do |form| %>
<div class="cropFields">
<% for attribute in [:crop_x, :crop_y, :crop_w, :crop_h] %>
<%= form.text_field attribute, id: attribute %>
<% end %>
</div>
<p><%= form.submit "Crop" %></p>
<% end %>