Class: TaliaUtil::ImageConversions

Inherits:
Object
  • Object
show all
Defined in:
lib/talia_util/image_conversions.rb

Overview

Helper class that provides an interface to convert images, create thumbnails and pyramid images. This provides a central point from which to call external conversion tools.

Since it calls the command line, it should be compatible both with JRuby and plain Ruby.

See TaliaCore::Intializer for the options that can be set for the image conversions

Class Method Summary collapse

Class Method Details

.convert_command ⇒ Object

Returns the command that is used for converting thumbnails



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# File 'lib/talia_util/image_conversions.rb', line 28

def convert_command
  @convert_command ||= if(defined?(TaliaCore))
    TaliaCore::CONFIG['convert_command'] || '/opt/local/bin/convert'
  elsif(defined?(CONVERT_COMMAND))
    CONVERT_COMMAND
  else
    raise(ArgumentError('Unconfigured convert command. If not in Talia, set CONVERT_COMMAND'))
  end
end

.create_pyramid(source, destination) ⇒ Object

Creates the pyramid image for IIP by running the configured system command. This automatically creates the file in the correct location (IIP root)



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# File 'lib/talia_util/image_conversions.rb', line 61

def create_pyramid(source, destination)
  # TODO: Options not configurable
  pyramid_command = "#{vips_command} im_vips2tiff \"#{source}\" \"#{destination}\":jpeg:85,tile:256x256,pyramid"
  execute_command(pyramid_command, destination)
end

.create_thumb(source, destination) ⇒ Object

Create the thumbnail by running the configured creation command. Options are taken from talia_core.yml



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# File 'lib/talia_util/image_conversions.rb', line 51

def create_thumb(source, destination)
  thumbnail_size = "#{thumb_options['width']}x#{thumb_options['height']}"
  thumbnail_force = %w(true yes).include?(thumb_options['force']) ? "-background transparent -gravity center -extent #{thumbnail_size}" : ''
  thumbnail_command = "#{convert_command} \"#{source}\" -quality 85 -thumbnail \"#{thumbnail_size}>\" #{thumbnail_force} \"#{destination}\""
  execute_command(thumbnail_command, destination)
end

.thumb_options ⇒ Object

Returns the options for the thumbnail



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# File 'lib/talia_util/image_conversions.rb', line 39

def thumb_options
  @thumb_options ||= if(defined?(TaliaCore))
    TaliaCore::CONFIG['thumb_options'] || { 'width' => '80', 'height' => '120' }
  elsif(defined?(THUMB_OPTIONS))
    THUMB_OPTIONS
  else
    raise(ArgumentError('Unconfigured thumbnail options. If not in Talia, set THUMB_OPTIONS'))
  end
end

.to_png(source, destination) ⇒ Object

Transforms the given image into a PNG image. Note that the .png suffix will automatically added to the destination name



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# File 'lib/talia_util/image_conversions.rb', line 69

def to_png(source, destination)
  destination = "#{destination}.png" unless(File.extname(destination) == '.png')
  convert_line = "#{convert_command} \"#{source}\" \"#{destination}\""
  execute_command(convert_line, destination)
end

.vips_command ⇒ Object

Returns the command that is used for converting images



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# File 'lib/talia_util/image_conversions.rb', line 17

def vips_command
  @vips_command ||= if(defined?(TaliaCore))
    TaliaCore::CONFIG['vips_command'] || '/opt/local/bin/vips'
  elsif(defined?(VIPS_COMMAND))
    VIPS_COMMAND
  else
    raise(ArgumentError('Unconfigured vips command. If not in Talia, set VIPS_COMMAND'))
  end
end