diff options
Diffstat (limited to 'activestorage/app/models/active_storage/variation.rb')
-rw-r--r-- | activestorage/app/models/active_storage/variation.rb | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/activestorage/app/models/active_storage/variation.rb b/activestorage/app/models/active_storage/variation.rb new file mode 100644 index 0000000000..da4af62666 --- /dev/null +++ b/activestorage/app/models/active_storage/variation.rb @@ -0,0 +1,81 @@ +# frozen_string_literal: true + +# 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 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. + def wrap(variator) + case variator + when self + variator + when String + decode variator + else + new variator + end + end + + # 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 <tt>ActiveStorage::Variant#key</tt>). + 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 returned by <tt>MiniMagick::Image.read(io)</tt>, + # and performs the +transformations+ against it. The transformed image instance is then returned. + def transform(image) + ActiveSupport::Notifications.instrument("transform.active_storage") do + transformations.each do |name, argument_or_subtransformations| + image.mogrify do |command| + if name.to_s == "combine_options" + argument_or_subtransformations.each do |subtransformation_name, subtransformation_argument| + pass_transform_argument(command, subtransformation_name, subtransformation_argument) + end + else + pass_transform_argument(command, name, argument_or_subtransformations) + end + end + 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 pass_transform_argument(command, method, argument) + if eligible_argument?(argument) + command.public_send(method, argument) + else + command.public_send(method) + end + end + + def eligible_argument?(argument) + argument.present? && argument != true + end +end |