Class: Media::Transmogrifier

Inherits:
Object
  • Object
show all
Defined in:
lib/media/transmogrifier.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = nil) ⇒ Transmogrifier

takes a has of options, some of which are required:

  • :input_file or (:input and :input_type)

  • :output_file or :output_type



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# File 'lib/media/transmogrifier.rb', line 46

def initialize(options=nil)
  self.name = self.class.to_s
  # we keep an instance in the transmogrifier list.
  # They only need to have the name set.
  return if options.nil?

  options = options.dup
  self.input       = options.delete(:input)
  self.input_file  = options.delete(:input_file)
  self.input_type  = options.delete(:input_type)
  self.output_file = options.delete(:output_file)
  self.output_type = options.delete(:output_type)
  self.options = options



  if input and input_type.nil?
    raise ArgumentError.new('input_type required if input specified')
  elsif input and input_file.nil?
    self.input_file = Media::TempFile.new(input, input_type)
  elsif input and input_file
    raise ArgumentError.new('cannot have both input and input_file')
  elsif input_file and input_type.nil?
    self.input_type = Media::MimeType.mime_type_from_extension(input_file)
  elsif input.nil? and input_file.nil?
    raise ArgumentError.new('input or input_file is required')
  end

  if output_file.nil? and output_type.nil?
    raise ArgumentError.new('output_file or output_type is required')
  elsif output_file.nil?
    self.output_file = Media::TempFile.new(nil, output_type)
  elsif output_type.nil?
    self.output_type = Media::MimeType.mime_type_from_extension(output_file)
  end

  debug self.class.name + " converting" +
    " #{input_file } ( #{input_type} ) to" +
    " #{output_file} ( #{output_type} )"

  set_temporary_outfile

end

Instance Attribute Details

#command_output ⇒ Object

output of last command run



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# File 'lib/media/transmogrifier.rb', line 38

def command_output
  @command_output
end

#input ⇒ Object

Returns the value of attribute input.



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# File 'lib/media/transmogrifier.rb', line 28

def input
  @input
end

#input_file ⇒ Object

Returns the value of attribute input_file.



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# File 'lib/media/transmogrifier.rb', line 29

def input_file
  @input_file
end

#input_type ⇒ Object

Returns the value of attribute input_type.



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# File 'lib/media/transmogrifier.rb', line 30

def input_type
  @input_type
end

#name ⇒ Object

Returns the value of attribute name.



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# File 'lib/media/transmogrifier.rb', line 26

def name
  @name
end

#options ⇒ Object

Returns the value of attribute options.



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# File 'lib/media/transmogrifier.rb', line 36

def options
  @options
end

#output ⇒ Object

maybe some day we return raw output via url?



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# File 'lib/media/transmogrifier.rb', line 32

def output
  @output
end

#output_file ⇒ Object

desired file location of the output



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# File 'lib/media/transmogrifier.rb', line 34

def output_file
  @output_file
end

#output_type ⇒ Object

desired mime type of the output



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# File 'lib/media/transmogrifier.rb', line 33

def output_type
  @output_type
end

Class Method Details

.add(trans) ⇒ Object 



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# File 'lib/media/transmogrifier.rb', line 108

def self.add(trans)
  self.list[trans.name] ||= trans
end

.find_class(input_type, output_type) ⇒ Object

returns transmogrifier class, if any, that can tranform input_type into output_type



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# File 'lib/media/transmogrifier.rb', line 116

def self.find_class(input_type, output_type)
  transmog = list.values.
    select{|tm| tm.converts_from?(input_type)}.
    select{|tm| tm.converts_to?(output_type)}.
    select{|tm| tm.available?}.
    first
  return transmog.class if transmog
  logger.error 'could not find a transmogrifier for "%s" -> "%s"' %
    [input_type, output_type]
  return nil
end

.inherited(base) ⇒ Object 



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# File 'lib/media/transmogrifier.rb', line 90

def self.inherited(base)
  add(base.new)
end

.input_map ⇒ Object

maps mine type to an array of transmogrifiers that take that type as an imput



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# File 'lib/media/transmogrifier.rb', line 102

def self.input_map; @@input_map ||= Hash.new([]); end

.list ⇒ Object

CLASS METHODS



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# File 'lib/media/transmogrifier.rb', line 98

def self.list(); @@list ||= {}; end

.output_map ⇒ Object

maps mine type to an array of transmogrifiers that produce that type as an output



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# File 'lib/media/transmogrifier.rb', line 106

def self.output_map; @@output_map ||= Hash.new([]); end

Instance Method Details

#command_available?(command) ⇒ Boolean

def self.command_available?(command)

command.present? and File.file?(command) and File.executable?(command)

end

Returns:

  • (Boolean) 


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# File 'lib/media/transmogrifier.rb', line 202

def command_available?(command)
  command and
  File.file?(command) and
  File.executable?(command)
end

#converts_from?(input_type) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/media/transmogrifier.rb', line 128

def converts_from?(input_type)
  input_types.include? input_type
end

#converts_to?(output_type) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/media/transmogrifier.rb', line 132

def converts_to?(output_type)
  output_types.include? output_type
end

#run_command(*args) ⇒ Object

runs a shell command, passing each line that is output, as it is output to the block.

returns the status of the command, as one of the following symbols: :success, :failure, :not_found, :error



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# File 'lib/media/transmogrifier.rb', line 153

def run_command(*args)

  # run the command
  cmdstr = command_string(*args)
  self.command_output = ""
  before = Time.now
  IO.popen(cmdstr + ' 2>&1', 'r') do |pipe|
    while line = pipe.gets
      if block_given?
        yield(line)
      end
      self.command_output << line << "\n"
    end
  end
  took = Time.now - before

  # set the status
  status = case $?.exitstatus
    when 0 then :success
    when 1 then :failure
    when 127 then :not_found
    else :error
  end
  if status == :success
    log_command cmdstr
    debug "took #{took} seconds."
    debug command_output
  else
    msg = ' exited with "%s"' % $?.exitstatus
    error cmdstr
    error msg
    error command_output if command_output.present?
    yield(msg) if block_given?
  end

  # restore the original output_file name
  unless restore_temporary_outfile
    msg = 'could not restore temporary outfile'
    error msg
    yield(msg) if block_given?
    status = :failure
  end
  return status
end