Module: AttachmentSaver::Processors::RMagick

Includes:
Image
Defined in:
lib/processors/r_magick.rb

Defined Under Namespace

Modules: Operations

Constant Summary

Constants included from Image

Image::DEFAULT_VALID_IMAGE_TYPES

Instance Method Summary collapse

Methods included from Image

#before_validate_attachment, #build_derived, #derived_image?, from_geometry_string, #image?, #process_attachment, #process_attachment?, #update_derived, #valid_image_type, #want_format?

Instance Method Details

#examine_image ⇒ Object 



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# File 'lib/processors/r_magick.rb', line 26

def examine_image
  with_image_attributes(uploaded_file_path) do |original_image|
    self.width = original_image.width if respond_to?(:width)
    self.height = original_image.height if respond_to?(:height)
    self.content_type = original_image.corrected_mime_type unless self.class.attachment_options[:keep_content_type] || original_image.corrected_mime_type.nil?
    self.file_extension = original_image.file_type_extension unless self.class.attachment_options[:keep_file_extension] || original_image.file_type_extension.nil?
  end
rescue AttachmentSaverError
  raise
rescue Exception => ex
  raise RMagickProcessorError, "#{ex.class}: #{ex.message}", ex.backtrace
end

#process_image(original_image, derived_format_name, resize_format) ⇒ Object 



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# File 'lib/processors/r_magick.rb', line 39

def process_image(original_image, derived_format_name, resize_format)
  resize_format = Image.from_geometry_string(resize_format) if resize_format.is_a?(String)

  result = original_image.send(*resize_format) do |derived_image|
    return nil unless want_format?(derived_format_name, derived_image.width, derived_image.height)

    # both original_filename and content_type must be defined for parents when using image processing
    # - but apps can just define them using attr_accessor if they don't want them persisted to db
    derived_content_type = derived_image.corrected_mime_type || original_image.corrected_mime_type || content_type
    derived_extension = derived_image.file_type_extension

    # we leverage tempfiles as discussed in the uploaded_file method
    temp = ExtendedTempfile.new("asrtemp", tempfile_directory, derived_extension)
    temp.binmode
    temp.close
    derived_image.write(temp.path)
    temp.open # we close & reopen so we see the file the processor wrote to, even if it created a new file rather than writing into our tempfile
  
    { :format_name => derived_format_name.to_s,
      :width => derived_image.width,
      :height => derived_image.height,
      :content_type => derived_content_type,
      :file_extension => derived_extension,
      :uploaded_data => temp }
  end

  # modern versions of RMagick don't leak memory.  however, the (many and large) internal
  # buffers malloced inside the ImageMagick library are not allocated via the Ruby memory
  # management functions.  as Ruby GC runs are normally triggered at the point when those Ruby
  # memory management functions request a larger heap, ImageMagick's extra allocations will
  # not trigger a GC run.  so while no memory has been leaked - all the allocations by the
  # ImageMagick library *will* get freed when GC runs - GC will typically not run even if you
  # process a series of images and end up using all of the memory that can be made available
  # to the process, at which point your process dies!  until such time as RMagick rewraps the
  # ImageMagick memory allocation functions to put them through Ruby's (as was done in the
  # as-yet-uncompleted MagickWand project), we force a GC after each image processing to
  # ensure that your processes stay happy.
  GC.start
  result
end

#with_image(filename, &block) ⇒ Object 



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# File 'lib/processors/r_magick.rb', line 16

def with_image(filename, &block)
  image = Magick::Image.read(filename).first
  block.call(image.extend(Operations))
end

#with_image_attributes(filename, &block) ⇒ Object 



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# File 'lib/processors/r_magick.rb', line 21

def with_image_attributes(filename, &block)
  image = Magick::Image.ping(filename).first
  block.call(image.extend(Operations))
end