Class: ActiveStorage::Variation

Inherits:
Object
  • Object
show all
Defined in:
app/models/active_storage/variation.rb

Overview

A set of transformations that can be applied to a blob to create a variant. This class is exposed via the ‘ActiveStorage::Blob#variant` method and should rarely be used directly.

In case you do need to use this directly, it’s instantiated using a hash of transformations where the key is the command and the value is the arguments. Example:

ActiveStorage::Variation.new(resize: "100x100", monochrome: true, trim: true, rotate: "-90")

A list of all possible transformations is available at www.imagemagick.org/script/mogrify.php.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(transformations) ⇒ Variation

Returns a new instance of Variation.



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# File 'app/models/active_storage/variation.rb', line 28

def initialize(transformations)
  @transformations = transformations
end

Instance Attribute Details

#transformations ⇒ Object (readonly)

Returns the value of attribute transformations.



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# File 'app/models/active_storage/variation.rb', line 13

def transformations
  @transformations
end

Class Method Details

.decode(key) ⇒ Object

Returns a variation instance with the transformations that were encoded by ‘#encode`.



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# File 'app/models/active_storage/variation.rb', line 17

def decode(key)
  new ActiveStorage.verifier.verify(key, purpose: :variation)
end

.encode(transformations) ⇒ Object

Returns a signed key for the ‘transformations`, which can be used to refer to a specific variation in a URL or combined key (like `ActiveStorage::Variant#key`).



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# File 'app/models/active_storage/variation.rb', line 23

def encode(transformations)
  ActiveStorage.verifier.generate(transformations, purpose: :variation)
end

Instance Method Details

#key ⇒ Object

Returns a signed key for all the ‘transformations` that this variation was instantiated with.



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# File 'app/models/active_storage/variation.rb', line 45

def key
  self.class.encode(transformations)
end

#transform(image) ⇒ Object

Accepts an open MiniMagick image instance, like what’s return by ‘MiniMagick::Image.read(io)`, and performs the `transformations` against it. The transformed image instance is then returned.



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# File 'app/models/active_storage/variation.rb', line 34

def transform(image)
  transformations.each do |(method, argument)|
    if eligible_argument?(argument)
      image.public_send(method, argument)
    else
      image.public_send(method)
    end
  end
end