159 lines
4.5 KiB
Ruby
159 lines
4.5 KiB
Ruby
# frozen_string_literal: true
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require_relative '../../reader'
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module TTFunk
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class Table
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class Glyf
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# Composite TrueType glyph.
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class Compound
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include Reader
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# Flags bit 0: arg1 and arg2 are words.
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ARG_1_AND_2_ARE_WORDS = 0x0001
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# Flags bit 3: there is a simple scale for the component.
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WE_HAVE_A_SCALE = 0x0008
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# Flags bit 5: at least one more glyph after this one.
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MORE_COMPONENTS = 0x0020
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# Flags bit 6: the x direction will use a different scale from the
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# y direction.
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WE_HAVE_AN_X_AND_Y_SCALE = 0x0040
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# Flags bit 7: there is a 2 by 2 transformation that will be used to
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# scale the component.
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WE_HAVE_A_TWO_BY_TWO = 0x0080
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# Flags bit 8: following the last component are instructions for the
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# composite character.
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WE_HAVE_INSTRUCTIONS = 0x0100
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# Glyph ID.
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# @return [Integer]
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attr_reader :id
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# Binary serialization of this glyph.
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# @return [String]
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attr_reader :raw
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# Number of contours in this glyph.
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# @return [Integer]
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attr_reader :number_of_contours
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# Minimum x for coordinate.
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# @return [Integer]
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attr_reader :x_min
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# Minimum y for coordinate.
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# @return [Integer]
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attr_reader :y_min
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# Maximum x for coordinate.
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# @return [Integer]
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attr_reader :x_max
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# Maximum y for coordinate.
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# @return [Integer]
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attr_reader :y_max
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# IDs of compound glyphs.
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attr_reader :glyph_ids
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# Component glyph.
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#
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# @!attribute [rw] flags
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# Component flag.
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# @return [Integer]
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# @!attribute [rw] glyph_index
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# Glyph index of component.
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# @return [Integer]
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# @!attribute [rw] arg1
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# x-offset for component or point number.
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# @return [Integer]
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# @!attribute [rw] arg2
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# y-offset for component or point number.
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# @return [Integer]
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# @!attribute [rw] transform
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# Transformation.
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# @return []
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Component = Struct.new(:flags, :glyph_index, :arg1, :arg2, :transform)
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# @param id [Integer] glyph ID.
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# @param raw [String]
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def initialize(id, raw)
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@id = id
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@raw = raw
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io = StringIO.new(raw)
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@number_of_contours, @x_min, @y_min, @x_max, @y_max =
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io.read(10).unpack('n*').map { |i|
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BinUtils.twos_comp_to_int(i, bit_width: 16)
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}
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# Because TTFunk only cares about glyphs insofar as they (1) provide
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# a bounding box for each glyph, and (2) can be rewritten into a
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# font subset, we don't really care about the rest of the glyph data
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# except as a whole. Thus, we don't actually decompose the glyph
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# into it's parts--all we really care about are the locations within
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# the raw string where the component glyph ids are stored, so that
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# when we rewrite this glyph into a subset we can rewrite the
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# component glyph-ids so they are correct for the subset.
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@glyph_ids = []
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@glyph_id_offsets = []
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offset = 10 # 2 bytes for each of num-contours, min x/y, max x/y
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loop do
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flags, glyph_id = @raw[offset, 4].unpack('n*')
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@glyph_ids << glyph_id
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@glyph_id_offsets << (offset + 2)
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break if (flags & MORE_COMPONENTS).zero?
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offset += 4
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offset +=
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if (flags & ARG_1_AND_2_ARE_WORDS).zero?
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2
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else
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4
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end
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if flags & WE_HAVE_A_TWO_BY_TWO != 0
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offset += 8
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elsif flags & WE_HAVE_AN_X_AND_Y_SCALE != 0
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offset += 4
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elsif flags & WE_HAVE_A_SCALE != 0
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offset += 2
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end
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end
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end
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# Is this a composite glyph?
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# @return [true]
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def compound?
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true
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end
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# Recode glyph.
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#
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# @param mapping [Hash{Integer => Integer}] a hash mapping old glyph IDs
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# to new glyph IDs.
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# @return [String]
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def recode(mapping)
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result = raw.dup
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new_ids = glyph_ids.map { |id| mapping[id] }
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new_ids.zip(@glyph_id_offsets).each do |new_id, offset|
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result[offset, 2] = [new_id].pack('n')
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end
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result
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end
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end
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end
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end
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end
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