Class: Skia::Typeface

Inherits:
Base
  • Object
show all
Defined in:
lib/skia/typeface.rb

Constant Summary collapse

WEIGHT_NORMAL = 
400
WEIGHT_BOLD = 
700
WIDTH_NORMAL = 
5

Instance Attribute Summary

Attributes inherited from Base

#ptr

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Base

#null?, release_callback, #to_ptr

Constructor Details

#initialize(ptr) ⇒ Typeface 



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# File 'lib/skia/typeface.rb', line 9

def initialize(ptr)
  super(ptr, :sk_typeface_unref)
end

Class Method Details

.default ⇒ Object 



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# File 'lib/skia/typeface.rb', line 32

def self.default
  ptr = Native.sk_typeface_create_default
  return nil if ptr.nil? || ptr.null?

  new(ptr)
end

.fixed_16_16_to_float(raw) ⇒ Object 



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# File 'lib/skia/typeface.rb', line 170

def self.fixed_16_16_to_float(raw)
  signed = raw >= 0x8000_0000 ? raw - 0x1_0000_0000 : raw
  signed / 65_536.0
end

.from_file(path, index = 0) ⇒ Object

Raises:



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# File 'lib/skia/typeface.rb', line 25

def self.from_file(path, index = 0)
  ptr = Native.sk_typeface_create_from_file(path, index)
  raise FileNotFoundError, "Failed to load typeface: #{path}" if ptr.nil? || ptr.null?

  new(ptr)
end

.from_name(name, weight: WEIGHT_NORMAL, width: WIDTH_NORMAL, slant: :upright) ⇒ Object 



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# File 'lib/skia/typeface.rb', line 13

def self.from_name(name, weight: WEIGHT_NORMAL, width: WIDTH_NORMAL, slant: :upright)
  style = Native.sk_fontstyle_new(weight, width, slant)
  begin
    ptr = Native.sk_typeface_create_from_name(name, style)
    return nil if ptr.nil? || ptr.null?

    new(ptr)
  ensure
    Native.sk_fontstyle_delete(style) if style && !style.null?
  end
end

.tag_to_string(tag_u32) ⇒ Object 



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# File 'lib/skia/typeface.rb', line 156

def self.tag_to_string(tag_u32)
  big_endian = [tag_u32].pack('N')
  return big_endian if big_endian.match?(/\A[\x20-\x7E]{4}\z/)

  [tag_u32].pack('V')
end

.tag_to_uint32(tag) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/skia/typeface.rb', line 163

def self.tag_to_uint32(tag)
  return tag if tag.is_a?(Integer)
  raise ArgumentError, 'tag must be a 4-character String or Integer' unless tag.is_a?(String) && tag.bytesize == 4

  tag.unpack1('N')
end

Instance Method Details

#family_name ⇒ Object 



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# File 'lib/skia/typeface.rb', line 39

def family_name
  read_native_string(:sk_typeface_get_family_name)
end

#fixed_pitch? ⇒ Boolean 



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# File 'lib/skia/typeface.rb', line 61

def fixed_pitch?
  Native.sk_typeface_is_fixed_pitch(@ptr)
end

#glyph_count ⇒ Object 



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# File 'lib/skia/typeface.rb', line 69

def glyph_count
  Native.sk_typeface_count_glyphs(@ptr)
end

#post_script_name ⇒ Object 



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# File 'lib/skia/typeface.rb', line 43

def post_script_name
  return nil unless Native.function_available?(:sk_typeface_get_post_script_name)

  read_native_string(:sk_typeface_get_post_script_name)
end

#slant ⇒ Object 



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# File 'lib/skia/typeface.rb', line 57

def slant
  Native.sk_typeface_get_font_slant(@ptr)
end

#style ⇒ Object 



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# File 'lib/skia/typeface.rb', line 73

def style
  {
    weight: weight,
    width: width,
    slant: slant,
    fixed_pitch: fixed_pitch?,
    units_per_em: units_per_em
  }
end

#table_count ⇒ Object 



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# File 'lib/skia/typeface.rb', line 83

def table_count
  Native.sk_typeface_count_tables(@ptr)
end

#table_data(tag) ⇒ Object 



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# File 'lib/skia/typeface.rb', line 96

def table_data(tag)
  tag_u32 = self.class.tag_to_uint32(tag)
  size = Native.sk_typeface_get_table_size(@ptr, tag_u32)
  return nil if size <= 0

  data_ptr = FFI::MemoryPointer.new(:uint8, size)
  bytes_read = Native.sk_typeface_get_table_data(@ptr, tag_u32, 0, size, data_ptr)
  return nil if bytes_read <= 0

  data_ptr.read_bytes(bytes_read)
end

#table_tags ⇒ Object 



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# File 'lib/skia/typeface.rb', line 87

def table_tags
  count = table_count
  return [] if count <= 0

  tags_ptr = FFI::MemoryPointer.new(:uint32, count)
  read_count = Native.sk_typeface_get_table_tags(@ptr, tags_ptr)
  tags_ptr.read_array_of_uint32(read_count).map { |tag| self.class.tag_to_string(tag) }
end

#units_per_em ⇒ Object 



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# File 'lib/skia/typeface.rb', line 65

def units_per_em
  Native.sk_typeface_get_units_per_em(@ptr)
end

#variation_axes ⇒ Object 



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# File 'lib/skia/typeface.rb', line 108

def variation_axes
  fvar = table_data('fvar')
  return [] if fvar.nil? || fvar.bytesize < 16

  version, offset_to_data, = fvar.unpack('Nn')
  return [] unless version == 0x0001_0000

  axis_count = fvar.byteslice(8, 2).unpack1('n')
  axis_size = fvar.byteslice(10, 2).unpack1('n')
  return [] if axis_count <= 0 || axis_size < 20

  axes = []
  axis_count.times do |index|
    offset = offset_to_data + (index * axis_size)
    break if offset + 20 > fvar.bytesize

    record = fvar.byteslice(offset, 20)
    tag = record.byteslice(0, 4)
    min_raw, default_raw, max_raw, flags, name_id = record.byteslice(4, 16).unpack('N3n2')

    axes << {
      tag: tag,
      min_value: self.class.fixed_16_16_to_float(min_raw),
      default_value: self.class.fixed_16_16_to_float(default_raw),
      max_value: self.class.fixed_16_16_to_float(max_raw),
      hidden: (flags & 0x0001) != 0,
      name_id: name_id
    }
  end

  axes
end

#weight ⇒ Object 



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# File 'lib/skia/typeface.rb', line 49

def weight
  Native.sk_typeface_get_font_weight(@ptr)
end

#width ⇒ Object 



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# File 'lib/skia/typeface.rb', line 53

def width
  Native.sk_typeface_get_font_width(@ptr)
end