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# 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_to_limit: [100, 100], monochrome: true, trim: true, rotate: "-90")
#
# The options map directly to {ImageProcessing}[https://github.com/janko-m/image_processing] commands.
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 a File object, performs the +transformations+ against it, and
# saves the transformed image into a temporary file. If +format+ is specified
# it will be the format of the result image, otherwise the result image
# retains the source format.
def transform(file, format: nil, &block)
ActiveSupport::Notifications.instrument("transform.active_storage") do
transformer.transform(file, format: format, &block)
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 transformer
if ActiveStorage.variant_processor
begin
require "image_processing"
rescue LoadError
ActiveSupport::Deprecation.warn <<~WARNING
Generating image variants will require the image_processing gem in Rails 6.1.
Please add `gem 'image_processing', '~> 1.2'` to your Gemfile.
WARNING
ActiveStorage::Transformers::MiniMagickTransformer.new(transformations)
else
ActiveStorage::Transformers::ImageProcessingTransformer.new(transformations)
end
else
ActiveStorage::Transformers::MiniMagickTransformer.new(transformations)
end
end
end
|
