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89 lines
3.2 KiB
Ruby
89 lines
3.2 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: "100x100", monochrome: true, trim: true, rotate: "-90")
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#
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# You can also combine multiple transformations in one step, e.g. for center-weighted cropping:
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#
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# ActiveStorage::Variation.new(combine_options: {
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# resize: "100x100^",
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# gravity: "center",
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# crop: "100x100+0+0",
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# })
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#
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# A list of all possible transformations is available at https://www.imagemagick.org/script/mogrify.php.
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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 an open MiniMagick image instance, like what's returned by <tt>MiniMagick::Image.read(io)</tt>,
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# and performs the +transformations+ against it. The transformed image instance is then returned.
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def transform(image)
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ActiveSupport::Notifications.instrument("transform.active_storage") do
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transformations.each do |name, argument_or_subtransformations|
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image.mogrify do |command|
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if name.to_s == "combine_options"
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argument_or_subtransformations.each do |subtransformation_name, subtransformation_argument|
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pass_transform_argument(command, subtransformation_name, subtransformation_argument)
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end
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else
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pass_transform_argument(command, name, argument_or_subtransformations)
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end
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end
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end
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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 pass_transform_argument(command, method, argument)
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if eligible_argument?(argument)
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command.public_send(method, argument)
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else
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command.public_send(method)
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end
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end
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def eligible_argument?(argument)
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argument.present? && argument != true
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end
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end
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