jcrop preview contains strange error

Question

I need help with my jcrop preview. I am following this tutorial from railscasts #182, but something is wrong and I can seem to figure it out. It is a bit difficult to explain but The crop preview doesn't work and a second image appears inside the crop resizing handles. This extra image stretches and skews with the resizing of the crop. Since this is a bit confusing and my app is still on my local machine, I have included a video demo of the current functionality as well what I assume is all of the relevant code below.

I also sent an email to jcrop and they suggested this could be caused by an error in my preview area. I assume this is correct as I am currently using the one provided by Ryan Bates' railscasts tut. The only other thing that I thought might be an issues is the "attr_accessible" and "attr_accessor". I am new to ruby and rails so I am have a bit of a difficult time understanding my errors. Any help would be greatly appreciated, please let me know if I can provide any further info.

First here is my avatar_uploader.rb

class AvatarUploader < CarrierWave::Uploader::Base
  include CarrierWave::RMagick

  storage :file

  # Override the directory where uploaded files will be stored.
  # This is a sensible default for uploaders that are meant to be mounted:
  def store_dir
    "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  end

  version :large do
    resize_to_limit(600, 600)
  end

  version :thumb do
    process :crop
    resize_to_fill(100, 100)
  end

  version :mini do
    process :crop
    resize_to_fill(48, 48)
  end

  version :nano do
    process :crop
    resize_to_fill(20, 20)
  end

  def crop
    if model.crop_x.present?
      resize_to_limit(600, 600)
      manipulate! do |img|
        x = model.crop_x.to_i
        y = model.crop_y.to_i
        w = model.crop_w.to_i
        h = model.crop_h.to_i
        img.crop!(x, y, w, h)
      end
    end
  end
end

user.rb

class User < ActiveRecord::Base
  belongs_to :team
  # Define roles
  ROLES = %w[admin conference president tailgater author banned]

  # Include default devise modules. Others available are:
  # :token_authenticatable, :encryptable, :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable

  # Setup accessible (or protected) attributes for your model
  attr_accessible :email, :password, :password_confirmation, :remember_me, 
                  :role, :avatar, :team_id
  #Include uploader
  mount_uploader :avatar, AvatarUploader
  attr_accessor :crop_x, :crop_y, :crop_w, :crop_h
  after_update :crop_avatar

  def crop_avatar
    avatar.recreate_versions! if crop_x.present?
  end

end

crop.html.erb

<h1>Crop Avatar</h1>

<%= image_tag @user.avatar_url(:large), id: "cropbox" %>

<h4>Preview</h4>
<div style="width:100px; height:100px; overflow:hidden">
  <%= image_tag @user.avatar.url(:large), :id => "mypreview" %>
</div>

<%= form_for @user do |f| %>
  <% %w[x y w h].each do |attribute| %>
    <%= f.hidden_field "crop_#{attribute}" %>
  <% end %>
  <div class="actions">
    <%= f.submit "Crop" %>
  </div>
<% end %>

users.js.coffee

jQuery ->
  new AvatarCropper()

class AvatarCropper
  constructor: ->
    $('#cropbox').Jcrop
      aspectRatio: 1
      setSelect: [0, 0, 600, 600]
      onSelect: @update
      onChange: @update

  update: (coords) =>
    $('#user_crop_x').val(coords.x)
    $('#user_crop_y').val(coords.y)
    $('#user_crop_w').val(coords.w)
    $('#user_crop_h').val(coords.h)
    @updatePreview(coords)

  updatePreview: (coords) =>
          $('#preview').css
                  width: Math.round(100/coords.w * $('#cropbox').width()) + 'px'
                  height: Math.round(100/coords.h * $('#cropbox').height()) + 'px'
                  marginLeft: '-' + Math.round(100/coords.w * coords.x) + 'px'
                  marginTop: '-' + Math.round(100/coords.h * coords.y) + 'px'

Answer 1

I had same issue as you. It is due to a conflict with bootstrap css. details and solutions can be found here.