Module: CarrierWave::MiniMagick

Defined in:
lib/carrierwave/processing/mini_magick.rb

Overview

This module simplifies manipulation with MiniMagick by providing a set of convenient helper methods. If you want to use them, you’ll need to require this file:

require 'carrierwave/processing/mini_magick'

And then include it in your uploader:

class MyUploader < CarrierWave::Uploader::Base
  include CarrierWave::MiniMagick
end

You can now use the provided helpers:

class MyUploader < CarrierWave::Uploader::Base
  include CarrierWave::MiniMagick

  process :resize_to_fit => [200, 200]
end

Or create your own helpers with the powerful manipulate! method. Check out the ImageMagick docs at www.imagemagick.org/script/command-line-options.php for more info

class MyUploader < CarrierWave::Uploader::Base
  include CarrierWave::MiniMagick

  process :do_stuff => 10.0

  def do_stuff(blur_factor)
    manipulate! do |img|
      img = img.sepiatone
      img = img.auto_orient
      img = img.radial_blur blur_factor
    end
  end
end

Note

MiniMagick is a mini replacement for RMagick that uses the command line tool “mogrify” for image manipulation.

You can find more information here:

mini_magick.rubyforge.org/ and github.com/probablycorey/mini_magick/

Defined Under Namespace

Modules: ClassMethods

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.included(base) ⇒ Object 



60
61
62
63
 
# File 'lib/carrierwave/processing/mini_magick.rb', line 60

def self.included(base)
  super
  base.extend(ClassMethods)
end

Instance Method Details

#convert(format) ⇒ Object

Changes the image encoding format to the given format

See www.imagemagick.org/script/command-line-options.php#format

Parameters

format (#to_s)

an abreviation of the format

Yields

MiniMagick::Image

additional manipulations to perform

Examples

image.convert(:png)



108
109
110
111
112
113
114
 
# File 'lib/carrierwave/processing/mini_magick.rb', line 108

def convert(format)
  manipulate! do |img|
    img.format(format.to_s.upcase)
    img = yield(img) if block_given?
    img
  end
end

#manipulate! ⇒ Object

Manipulate the image with RMagick. This method will load up an image and then pass each of its frames to the supplied block. It will then save the image to disk.

Gotcha

This method assumes that the object responds to current_path. Any class that this module is mixed into must have a current_path method. CarrierWave::Uploader does, so you won’t need to worry about this in most cases.

Yields

MiniMagick::Image

manipulations to perform

Raises

CarrierWave::ProcessingError

if manipulation failed.



259
260
261
262
263
264
265
266
 
# File 'lib/carrierwave/processing/mini_magick.rb', line 259

def manipulate!
  image = ::MiniMagick::Image.from_file(current_path)
  image = yield(image)
  image.write(current_path)
  ::MiniMagick::Image.from_file(current_path)
rescue ::MiniMagick::MiniMagickError => e
  raise CarrierWave::ProcessingError.new("Failed to manipulate with MiniMagick, maybe it is not an image? Original Error: #{e}")
end

#resize_and_pad(width, height, background = :transparent, gravity = 'Center') ⇒ Object

Resize the image to fit within the specified dimensions while retaining the original aspect ratio. If necessary, will pad the remaining area with the given color, which defaults to transparent (for gif and png, white for jpeg).

See www.imagemagick.org/script/command-line-options.php#gravity for gravity options.

Parameters

width (Integer)

the width to scale the image to

height (Integer)

the height to scale the image to

background (String, :transparent)

the color of the background as a hexcode, like “#ff45de”

gravity (String)

how to position the image

Yields

MiniMagick::Image

additional manipulations to perform



222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
 
# File 'lib/carrierwave/processing/mini_magick.rb', line 222

def resize_and_pad(width, height, background=:transparent, gravity='Center')
  manipulate! do |img|
    img.combine_options do |cmd|
      cmd.thumbnail "#{width}x#{height}>"
      if background == :transparent
        cmd.background "rgba(0, 0, 0, 0.0)"
      else
        cmd.background background
      end
      cmd.gravity gravity
      cmd.extent "#{width}x#{height}"
    end
    img = yield(img) if block_given?
    img
  end
end

#resize_to_fill(width, height, gravity = 'Center') ⇒ Object

From the RMagick documentation: “Resize the image to fit within the specified dimensions while retaining the aspect ratio of the original image. If necessary, crop the image in the larger dimension.”

See even www.imagemagick.org/RMagick/doc/image3.html#resize_to_fill

and

www.clipclip.org/clips/detail/4365/jerrett-net-»-crop_resized-in-rmagick

Parameters

width (Integer)

the width to scale the image to

height (Integer)

the height to scale the image to

Yields

MiniMagick::Image

additional manipulations to perform



184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
 
# File 'lib/carrierwave/processing/mini_magick.rb', line 184

def resize_to_fill(width, height, gravity = 'Center')
  manipulate! do |img|
    cols, rows = img[:dimensions]
    img.combine_options do |cmd|
      if width != cols || height != rows
        scale = [width/cols.to_f, height/rows.to_f].max
        cols = (scale * (cols + 0.5)).round
        rows = (scale * (rows + 0.5)).round
        cmd.resize "#{cols}x#{rows}"
      end
      cmd.gravity gravity
      cmd.extent "#{width}x#{height}" if cols != width || rows != height
    end
    img = yield(img) if block_given?
    img
  end
end

#resize_to_fit(width, height) ⇒ Object

From the RMagick documentation: “Resize the image to fit within the specified dimensions while retaining the original aspect ratio. The image may be shorter or narrower than specified in the smaller dimension but will not be larger than the specified values.”

See even www.imagemagick.org/RMagick/doc/image3.html#resize_to_fit

Parameters

width (Integer)

the width to scale the image to

height (Integer)

the height to scale the image to

Yields

MiniMagick::Image

additional manipulations to perform



156
157
158
159
160
161
162
 
# File 'lib/carrierwave/processing/mini_magick.rb', line 156

def resize_to_fit(width, height)
  manipulate! do |img|
    img.resize "#{width}x#{height}"
    img = yield(img) if block_given?
    img
  end
end

#resize_to_limit(width, height) ⇒ Object

Resize the image to fit within the specified dimensions while retaining the original aspect ratio. Will only resize the image if it is larger than the specified dimensions. The resulting image may be shorter or narrower than specified in the smaller dimension but will not be larger than the specified values.

Parameters

width (Integer)

the width to scale the image to

height (Integer)

the height to scale the image to

Yields

MiniMagick::Image

additional manipulations to perform



131
132
133
134
135
136
137
 
# File 'lib/carrierwave/processing/mini_magick.rb', line 131

def resize_to_limit(width, height)
  manipulate! do |img|
    img.resize "#{width}x#{height}>"
    img = yield(img) if block_given?
    img
  end
end