Method: CIFilter._create_filter

Defined in:
lib/sugarcube-image/cifilter.rb

._create_filter(filter_name, args, set_args = [], names = {}) ⇒ Object

This helper instantiates the filter (raising an exception if it was unsuccessful) and applies all the arguments from options (naming the args according to set_args), translating names from names



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# File 'lib/sugarcube-image/cifilter.rb', line 83

def _create_filter(filter_name, args, set_args=[], names={})
  filter = CIFilter.filterWithName(filter_name)
  raise "Unsupported filter #{filter_name.inspect}" unless filter

  # turn a list of arguments into a hash
  if args.length == 1 && Hash === args[0]
    options = args[0]
  else
    options = {}
    args.each_with_index do |arg, index|
      setter = set_args[index]
      raise "Cannot set option ##{index}" if setter.nil?
      options[setter] = arg
    end
  end

  options.each do |key, value|
    # translate the keys, but if there is no translation key then do nothing
    key = names[key] || key.to_s

    # translate the value if a block was given for that. `key` is always going
    # to be the CIImage key (not the alias, e.g. :radius => 'inputRadius')
    value = yield(key, value) if block_given?
    filter.setValue(value, forKey:key)
  end
  return filter
end