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_to_limit: [100, 100], colourspace: "b-w", rotate: "-90", saver: { trim: true })
The options map directly to ImageProcessing commands.
# File activestorage/app/models/active_storage/variation.rb, line 33 def decode(key) new ActiveStorage.verifier.verify(key, purpose: :variation) end
Returns a Variation
instance with the transformations that were encoded by encode
.
# File activestorage/app/models/active_storage/variation.rb, line 39 def encode(transformations) ActiveStorage.verifier.generate(transformations, purpose: :variation) end
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
).
# File activestorage/app/models/active_storage/variation.rb, line 44 def initialize(transformations) @transformations = transformations.deep_symbolize_keys end
# File activestorage/app/models/active_storage/variation.rb, line 21 def wrap(variator) case variator when self variator when String decode variator else new variator end end
Returns a Variation
instance based on the given variator. If the variator is a Variation
, it is returned unmodified. If it is a String
, it is passed to ActiveStorage::Variation.decode
. Otherwise, it is assumed to be a transformations Hash
and is passed directly to the constructor.
# File activestorage/app/models/active_storage/variation.rb, line 68 def content_type MiniMime.lookup_by_extension(format.to_s).content_type end
# File activestorage/app/models/active_storage/variation.rb, line 48 def default_to(defaults) self.class.new transformations.reverse_merge(defaults) end
# File activestorage/app/models/active_storage/variation.rb, line 77 def digest OpenSSL::Digest::SHA1.base64digest Marshal.dump(transformations) end
# File activestorage/app/models/active_storage/variation.rb, line 60 def format transformations.fetch(:format, :png).tap do |format| if MiniMime.lookup_by_extension(format.to_s).nil? raise ArgumentError, "Invalid variant format (#{format.inspect})" end end end
# File activestorage/app/models/active_storage/variation.rb, line 73 def key self.class.encode(transformations) end
Returns a signed key for all the transformations
that this variation was instantiated with.
# File activestorage/app/models/active_storage/variation.rb, line 54 def transform(file, &block) ActiveSupport::Notifications.instrument("transform.active_storage") do transformer.transform(file, format: format, &block) end end
Accepts a File
object, performs the transformations
against it, and saves the transformed image into a temporary file.
© 2004–2021 David Heinemeier Hansson
Licensed under the MIT License.