Class: ImageProcessing::Processor

Inherits:
Object
  • Object
show all
Defined in:
lib/image_processing/processor.rb

Overview

Abstract class inherited by individual processors.

Direct Known Subclasses

MiniMagick::Processor, Vips::Processor

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(accumulator = nil) ⇒ Processor

Returns a new instance of Processor.



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# File 'lib/image_processing/processor.rb', line 47

def initialize(accumulator = nil)
  @accumulator = accumulator
end

Class Method Details

.accumulator(name, klass) ⇒ Object

Use for processor subclasses to specify the name and the class of their accumulator object (e.g. MiniMagick::Tool or Vips::Image).



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# File 'lib/image_processing/processor.rb', line 31

def self.accumulator(name, klass)
  define_method(name) { @accumulator }
  protected(name)
  const_set(:ACCUMULATOR_CLASS, klass)
end

.apply_operation(accumulator, name, args, block) ⇒ Object

Delegates to #apply_operation.



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# File 'lib/image_processing/processor.rb', line 38

def self.apply_operation(accumulator, (name, args, block))
  new(accumulator).apply_operation(name, *args, &block)
end

.call(source:, loader:, operations:, saver:, destination: nil) ⇒ Object 



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# File 'lib/image_processing/processor.rb', line 4

def self.call(source:, loader:, operations:, saver:, destination: nil)
  unless source.is_a?(String) || source.is_a?(self::ACCUMULATOR_CLASS)
    fail Error, "invalid source: #{source.inspect}"
  end

  if operations.dig(0, 0).to_s.start_with?("resize_") &&
     loader.empty? &&
     supports_resize_on_load?

    accumulator = source
  else
    accumulator = load_image(source, **loader)
  end

  operations.each do |operation|
    accumulator = apply_operation(accumulator, operation)
  end

  if destination
    save_image(accumulator, destination, **saver)
  else
    accumulator
  end
end

.supports_resize_on_load? ⇒ Boolean

Whether the processor supports resizing the image upon loading.

Returns:

  • (Boolean) 


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# File 'lib/image_processing/processor.rb', line 43

def self.supports_resize_on_load?
  false
end

Instance Method Details

#apply_operation(name, *args, &block) ⇒ Object

Calls the operation to perform the processing. If the operation is defined on the processor (macro), calls the method. Otherwise calls the operation directly on the accumulator object. This provides a common umbrella above defined macros and direct operations.



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# File 'lib/image_processing/processor.rb', line 55

def apply_operation(name, *args, &block)
  # Chainable performs the same check when operations are built, but that
  # guard only sees the outer builder method name, so it can be routed
  # around via the #operation meta-builder, #method_missing, or a nested
  # #send. This is the single point every operation is finally dispatched
  # through, so enforcing the guard here closes all of those paths.
  if ImageProcessing.unsafe_method?(self, name)
    fail Error, "#{name.inspect} is not a valid operation"
  end

  receiver = respond_to?(name) ? self : @accumulator

  if args.last.is_a?(Hash)
    kwargs = args.pop
    receiver.public_send(name, *args, **kwargs, &block)
  else
    receiver.public_send(name, *args, &block)
  end
end

#custom(&block) ⇒ Object

Calls the given block with the accumulator object. Useful for when you want to access the accumulator object directly.



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# File 'lib/image_processing/processor.rb', line 77

def custom(&block)
  (block && block.call(@accumulator)) || @accumulator
end