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80 lines
2.9 KiB
Ruby
80 lines
2.9 KiB
Ruby
# frozen_string_literal: true
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# A set of transformations that can be applied to a blob to create a variant. This class is exposed via
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# the ActiveStorage::Blob#variant method and should rarely be used directly.
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#
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# In case you do need to use this directly, it's instantiated using a hash of transformations where
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# the key is the command and the value is the arguments. Example:
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#
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# ActiveStorage::Variation.new(resize_to_fit: [100, 100], monochrome: true, trim: true, rotate: "-90")
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#
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# The options map directly to {ImageProcessing}[https://github.com/janko-m/image_processing] commands.
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class ActiveStorage::Variation
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attr_reader :transformations
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class << self
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# Returns a Variation instance based on the given variator. If the variator is a Variation, it is
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# returned unmodified. If it is a String, it is passed to ActiveStorage::Variation.decode. Otherwise,
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# it is assumed to be a transformations Hash and is passed directly to the constructor.
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def wrap(variator)
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case variator
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when self
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variator
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when String
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decode variator
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else
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new variator
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end
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end
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# Returns a Variation instance with the transformations that were encoded by +encode+.
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def decode(key)
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new ActiveStorage.verifier.verify(key, purpose: :variation)
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end
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# Returns a signed key for the +transformations+, which can be used to refer to a specific
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# variation in a URL or combined key (like <tt>ActiveStorage::Variant#key</tt>).
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def encode(transformations)
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ActiveStorage.verifier.generate(transformations, purpose: :variation)
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end
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end
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def initialize(transformations)
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@transformations = transformations
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end
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# Accepts a File object, performs the +transformations+ against it, and
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# saves the transformed image into a temporary file. If +format+ is specified
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# it will be the format of the result image, otherwise the result image
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# retains the source format.
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def transform(file, format: nil, &block)
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ActiveSupport::Notifications.instrument("transform.active_storage") do
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transformer.transform(file, format: format, &block)
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end
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end
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# Returns a signed key for all the +transformations+ that this variation was instantiated with.
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def key
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self.class.encode(transformations)
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end
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private
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def transformer
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if ActiveStorage.variant_processor
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begin
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require "image_processing"
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rescue LoadError
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ActiveSupport::Deprecation.warn <<~WARNING
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Generating image variants will require the image_processing gem in Rails 6.1.
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Please add `gem 'image_processing', '~> 1.2'` to your Gemfile.
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WARNING
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ActiveStorage::Transformers::MiniMagickTransformer.new(transformations)
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else
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ActiveStorage::Transformers::ImageProcessingTransformer.new(transformations)
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end
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else
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ActiveStorage::Transformers::MiniMagickTransformer.new(transformations)
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end
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end
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end
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