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A Transformer applies a set of transformations to an image.

The following concrete subclasses are included in Active Storage:

  • ActiveStorage::Transformers::ImageProcessingTransformer: backed by ImageProcessing, a common interface for MiniMagick and ruby-vips

  • ActiveStorage::Transformers::MiniMagickTransformer: backed by MiniMagick, a wrapper around the ImageMagick CLI

Methods
N
P
T
Attributes
[R] transformations
Class Public methods
new(transformations)
# File activestorage/lib/active_storage/transformers/transformer.rb, line 17
def initialize(transformations)
  @transformations = transformations
end
Instance Public methods
transform(file, format:)

Applies the transformations to the source image in file, producing a target image in the specified format. Yields an open Tempfile containing the target image. Closes and unlinks the output tempfile after yielding to the given block. Returns the result of the block.

# File activestorage/lib/active_storage/transformers/transformer.rb, line 24
def transform(file, format:)
  output = process(file, format: format)

  begin
    yield output
  ensure
    output.close!
  end
end
Instance Private methods
process(file, format:)

Returns an open Tempfile containing a transformed image in the given format. All subclasses implement this method.

# File activestorage/lib/active_storage/transformers/transformer.rb, line 37
def process(file, format:) #:doc:
  raise NotImplementedError
end