Module: Cul::Hydra::Models::ImageResource

Included in:
GenericResource
Defined in:
app/models/concerns/cul/hydra/models/image_resource.rb

Constant Summary collapse

IMAGE_EXT = 
{"image/bmp" => 'bmp', "image/gif" => 'gif', "image/jpeg" => 'jpg', "image/png" => 'png', "image/tiff" => 'tif', "image/x-windows-bmp" => 'bmp', 'image/jp2' => 'jp2'}
WIDTH = 
RDF::URI(ActiveFedora::Predicates.find_graph_predicate(:image_width))
LENGTH = 
RDF::URI(ActiveFedora::Predicates.find_graph_predicate(:image_length))
WIDTH_PREDICATE = 
ActiveFedora::Predicates.short_predicate("http://www.w3.org/2003/12/exif/ns#imageWidth").to_s
LENGTH_PREDICATE = 
ActiveFedora::Predicates.short_predicate("http://www.w3.org/2003/12/exif/ns#imageLength").to_s
EXTENT_PREDICATE = 
ActiveFedora::Predicates.short_predicate("http://purl.org/dc/terms/extent").to_s
FORMAT_OF_PREDICATE = 
ActiveFedora::Predicates.short_predicate("http://purl.org/dc/terms/isFormatOf").to_s
FORMAT_URI = 
RDF::URI("http://purl.org/dc/terms/format")
EXIF_ORIENTATION_TO_DEGREES = 
{
  'top-left' => 0,
  'left-bottom' => 90,
  'bottom-right' => 180,
  'right-top' => 270
}
DEGREES_TO_EXIF_ORIENTATIONS = 
EXIF_ORIENTATION_TO_DEGREES.invert

Instance Method Summary collapse

Instance Method Details

#length ⇒ Object 



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# File 'app/models/concerns/cul/hydra/models/image_resource.rb', line 35

def length
  @length ||= begin
    ds = datastreams["content"]
    length = 0
    unless ds.nil? or rels_int.relationships(ds,:exif_image_length).blank?
      length = rels_int.relationships(ds,:exif_image_length).first.object.to_s.to_i
    end
    length = relationships(:image_length).first.to_s.to_i if length == 0
    length
  end
end

#long ⇒ Object 



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# File 'app/models/concerns/cul/hydra/models/image_resource.rb', line 19

def long
  @long_side ||= max(width(), length())
end

#orientation ⇒ Object 



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# File 'app/models/concerns/cul/hydra/models/image_resource.rb', line 62

def orientation
  self.relationships(:orientation).present? ? EXIF_ORIENTATION_TO_DEGREES[self.relationships(:orientation).first.to_s] : 0
end

#orientation=(degrees) ⇒ Object

Allowed degrees arg values: 0, 90, 180, 270



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# File 'app/models/concerns/cul/hydra/models/image_resource.rb', line 54

def orientation=(degrees)
  degrees = degrees % 360
  raise "Invalid value for degrees.  Must be a right angle (0, 90, 180, etc.)" unless (degrees % 90 == 0)
  self.clear_relationship(:orientation)
  self.add_relationship(:orientation, DEGREES_TO_EXIF_ORIENTATIONS[degrees], true)
  return degrees # Hide RDF backing structure and make this look like a simple setter method
end

#required_rotation_for_upright_display ⇒ Object

The number of rotational degrees required to display this image as upright



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# File 'app/models/concerns/cul/hydra/models/image_resource.rb', line 48

def required_rotation_for_upright_display
  required_rotation_orientation_in_degrees = (360 - self.orientation) % 360
  return required_rotation_orientation_in_degrees
end

#width ⇒ Object 



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# File 'app/models/concerns/cul/hydra/models/image_resource.rb', line 23

def width
  @width ||= begin
    ds = datastreams["content"]
    width = 0
    unless ds.nil? or rels_int.relationships(ds,:exif_image_width).blank?
      width = rels_int.relationships(ds,:exif_image_width).first.object.to_s.to_i
    end
    width = relationships(:image_width).first.to_s.to_i if width == 0
    width
  end
end