require "active_support/core_ext/object/inclusion" # 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 https://www.imagemagick.org/script/mogrify.php. class ActiveStorage::Variation attr_reader :transformations class << self # Returns a variation instance with the transformations that were encoded by +#encode+. def decode(key) new ActiveStorage.verifier.verify(key, 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`). def encode(transformations) ActiveStorage.verifier.generate(transformations, purpose: :variation) end end def initialize(transformations) @transformations = transformations end # 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. 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 # Returns a signed key for all the +transformations+ that this variation was instantiated with. def key self.class.encode(transformations) end private def eligible_argument?(argument) argument.present? && argument != true end end