Module: AttachmentSaver::Processors::ImageScience

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

Defined Under Namespace

Modules: Operations

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, #want_format?

Instance Method Details

#examine_attachment ⇒ Object 



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# File 'lib/processors/image_science.rb', line 22

def examine_attachment
  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.mime_type unless self.class.attachment_options[:keep_content_type] || original_image.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 ImageScienceProcessorError, "#{ex.class}: #{ex.message}", ex.backtrace
end

#process_image(original_image, derived_format_name, resize_format) ⇒ Object 



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# File 'lib/processors/image_science.rb', line 35

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

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

    if derived_image.file_type == 'GIF' # && derived_image.depth != 8 # TODO: submit patch to add depth attribute
      # as a special case hack, don't try and save 24-bit derived images into 8-bit-only GIF format
      # (ImageScience doesn't resample back down, so it throws errors if we try to do that)
      derived_content_type = 'image/png'
      derived_extension = 'png'
    else
      # 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.mime_type || original_image.mime_type || content_type # note that mime_type will return nil instead of returning any of the freeimage-invented content types
      derived_extension = (derived_image.file_type || file_extension).downcase # in fact, derived_image.file_type should always work; the only situation in which it could return nil is if freeimage is extended to support a new image format but image_science_extensions isn't updated
    end

    # we leverage tempfiles as discussed in the uploaded_file method
    temp = ExtendedTempfile.new("asitemp", tempfile_directory, derived_extension)
    temp.binmode
    temp.close
    derived_image.save(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
end

#with_image(filename, &block) ⇒ Object 



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# File 'lib/processors/image_science.rb', line 13

def with_image(filename, &block)
  ::ImageScience.with_image(filename) {|image| block.call(image.extend(Operations))}
end

#with_image_attributes(filename, &block) ⇒ Object 



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# File 'lib/processors/image_science.rb', line 17

def with_image_attributes(filename, &block)
  return with_image(filename, &block) unless ::ImageScience.respond_to?(:with_image_attributes)
  ::ImageScience.with_image_attributes(filename) {|image| block.call(image)}
end