Class: Fontisan::Ufo::ImageSet

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/fontisan/ufo/image_set.rb

Overview

UFO 3 background image set. Lives at UFO/images/ in a UFO source directory. Each image is a PNG file referenced by glyph GLIF <image fileName="..."/> elements.

Per the UFO 3 spec, image files are arbitrary binary blobs (in practice always PNG). The image set deduplicates by content hash (sha256) so the same image referenced from multiple glyphs takes one slot.

Examples:

Read images from a UFO directory

imageset = ImageSet.load_from_dir("MyFont.ufo/images")
imageset.each { |img| puts img.file_name }

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ ImageSet

Returns a new instance of ImageSet.



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# File 'lib/fontisan/ufo/image_set.rb', line 25

def initialize
  @images = {}
end

Instance Attribute Details

#images ⇒ Hash{String=>Image} (readonly)

Returns filename → Image.

Returns:

  • (Hash{String=>Image}) —

    filename → Image



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# File 'lib/fontisan/ufo/image_set.rb', line 23

def images
  @images
end

Class Method Details

.load_from_dir(dir) ⇒ ImageSet

Load all PNG files from a UFO images/ directory.

Parameters:

  • dir (String) —

    path to the images directory

Returns:



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# File 'lib/fontisan/ufo/image_set.rb', line 33

def self.load_from_dir(dir)
  is = new
  return is unless File.directory?(dir)

  Dir.each_child(dir).sort.each do |name|
    path = File.join(dir, name)
    next unless File.file?(path)

    is.register_file(name, File.binread(path))
  end
  is
end

Instance Method Details

#count ⇒ Object

Number of registered images.



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# File 'lib/fontisan/ufo/image_set.rb', line 79

def count
  @images.size
end

#each ⇒ Object

Iterate over images in filename order.



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# File 'lib/fontisan/ufo/image_set.rb', line 72

def each(&)
  return enum_for(:each) unless block_given?

  @images.each_value(&)
end

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/fontisan/ufo/image_set.rb', line 83

def empty?
  @images.empty?
end

#find(file_name) ⇒ Image? Also known as: []

Look up an image by its filename.

Parameters:

  • file_name (String)

Returns:



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# File 'lib/fontisan/ufo/image_set.rb', line 66

def find(file_name)
  @images[file_name.to_s]
end

#register_file(file_name, bytes) ⇒ Image

Register an image from its filename and raw bytes. Computes the sha256 content hash automatically.

Parameters:

  • file_name (String)
  • bytes (String) —

    binary image data

Returns:



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# File 'lib/fontisan/ufo/image_set.rb', line 52

def register_file(file_name, bytes)
  image = Image.new(
    file_name: file_name,
    sha: Digest::SHA256.hexdigest(bytes),
    bytes: bytes,
  )
  @images[file_name.to_s] = image
  image
end

#write_to_dir(dir) ⇒ Object

Write all images to a target images/ directory. Useful for UFO round-trip serialization.

Parameters:

  • dir (String) —

    target images directory path



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# File 'lib/fontisan/ufo/image_set.rb', line 91

def write_to_dir(dir)
  FileUtils.mkpath(dir) unless File.directory?(dir)
  @images.each do |name, img|
    File.binwrite(File.join(dir, name), img.bytes)
  end
end