# -*- encoding: utf-8; frozen_string_literal: true -*-
#
#--
# This file is part of HexaPDF.
#
# HexaPDF - A Versatile PDF Creation and Manipulation Library For Ruby
# Copyright (C) 2014-2019 Thomas Leitner
#
# HexaPDF is free software: you can redistribute it and/or modify it
# under the terms of the GNU Affero General Public License version 3 as
# published by the Free Software Foundation with the addition of the
# following permission added to Section 15 as permitted in Section 7(a):
# FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
# THOMAS LEITNER, THOMAS LEITNER DISCLAIMS THE WARRANTY OF NON
# INFRINGEMENT OF THIRD PARTY RIGHTS.
#
# HexaPDF is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public
# License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with HexaPDF. If not, see <http://www.gnu.org/licenses/>.
#
# The interactive user interfaces in modified source and object code
# versions of HexaPDF must display Appropriate Legal Notices, as required
# under Section 5 of the GNU Affero General Public License version 3.
#
# In accordance with Section 7(b) of the GNU Affero General Public
# License, a covered work must retain the producer line in every PDF that
# is created or manipulated using HexaPDF.
#
# If the GNU Affero General Public License doesn't fit your need,
# commercial licenses are available at <https://gettalong.at/hexapdf/>.
#++

require 'hexapdf/font/true_type/table'
require 'hexapdf/utils/bit_field'

module HexaPDF
  module Font
    module TrueType
      class Table

        # The 'OS/2' table contains information required by Windows.
        #
        # Some attributes may be +nil+ when read from a file depending on the version of the table.
        #
        # See: https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6OS2.html
        class OS2 < Table

          extend HexaPDF::Utils::BitField

          # The version of the table.
          attr_accessor :version

          # AVerage weighted advance width of lower case letters and space.
          attr_accessor :x_avg_char_width

          # Visual weight of stroke in glyphs.
          attr_accessor :weight_class

          # Relative change from the normal aspect ratio (width/height).
          attr_accessor :width_class

          # Characteristics and properties of this font.
          attr_accessor :type
          bit_field(:type, {restricted_license_embedding: 1, preview_and_print_embedding: 2,
                            editable_embedding: 3, no_subsetting: 8, bitmap_embedding_only: 9})

          # Recommended horizontal size in pixels for subscripts
          attr_accessor :subscript_x_size

          # Recommended vertical size in pixels for subscripts
          attr_accessor :subscript_y_size

          # Recommended horizontal offset for subscripts.
          attr_accessor :subscript_x_offset

          # Recommended vertical offset from the baseline for subscripts.
          attr_accessor :subscript_y_offset

          # Recommended horizontal size in pixels for superscripts
          attr_accessor :superscript_x_size

          # Recommended vertical size in pixels for superscripts
          attr_accessor :superscript_y_size

          # Recommended horizontal offset for superscripts.
          attr_accessor :superscript_x_offset

          # Recommended vertical offset from the baseline for superscripts.
          attr_accessor :superscript_y_offset

          # Width of the strikeout stroke.
          attr_accessor :strikeout_size

          # Position of the strikeout stroke relative to the baseline.
          attr_accessor :strikeout_position

          # Classification of the font-family design.
          attr_accessor :family_class

          # Describes the visual characteristics of the given typeface.
          attr_accessor :panose

          # Describes the Unicode ranges covered by the font.
          attr_accessor :unicode_range

          # The four character identifier of the font vendor.
          attr_accessor :vendor_id

          # Information concerning the nature of the font patterns.
          attr_accessor :selection
          bit_field(:selection, {italic: 0, underscore: 1, negative: 2, outlined: 3, strikeout: 4,
                                 bold: 5, regular: 6, use_typo_metrics: 7, wws: 8, oblique: 9})

          # The minimum Unicode index in this font.
          attr_accessor :first_char_index

          # The maximum Unicode index in this font.
          attr_accessor :last_char_index

          # The typographic ascender. May not be the same as the ascender in the 'hhea' table.
          attr_accessor :typo_ascender

          # The typographic descender. May not be the same as the ascender in the 'hhea' table.
          attr_accessor :typo_descender

          # The typographic line gap. May not be the same as the ascender in the 'hhea' table.
          attr_accessor :typo_line_gap

          # The ascender metric for Windows.
          attr_accessor :win_ascent

          # The descender metric for Windows.
          attr_accessor :win_descent

          # The code page character range.
          attr_accessor :code_page_range

          # The distance between the baseline and the approximate height of non-ascending lowercase
          # letters.
          attr_accessor :x_height

          # The distance between the baseline and the approximate height of uppercase letters.
          attr_accessor :cap_height

          # The default character displayed by Windows to represent an unsupported character.
          attr_accessor :default_char

          # The break character used by Windows.
          attr_accessor :break_char

          # The maximum length of an OpenType context for any feature in this font.
          attr_accessor :max_context

          # The lowest size at which the font starts to be used.
          attr_accessor :lower_point_size

          # The highest size at which the font starts to be used.
          attr_accessor :upper_point_size

          private

          def parse_table #:nodoc:
            @version, @x_avg_char_width, @weight_class, @width_class, @type, @subscript_x_size,
              @subscript_y_size, @subscript_x_offset, @subscript_y_offset, @superscript_x_size,
              @superscript_y_size, @superscript_x_offset, @superscript_y_offset, @strikeout_size,
              @strikeout_position, @family_class, @panose =
              read_formatted(42, 'ns>n2s>12a10')

            @weight_class *= 100 if @weight_class < 100 # Normalize to standard weights

            @unicode_range, temp = read_formatted(16, 'Q>2')
            @unicode_range = @unicode_range << 64 & temp

            @vendor_id, @selection,
              @first_char_index, @last_char_index, @typo_ascender, @typo_descender, @typo_line_gap,
              @win_ascent, @win_descent, @code_page_range, @x_height, @cap_height, @default_char,
              @break_char, @max_context, @lower_point_size, @upper_point_size =
              read_formatted(directory_entry.length - 58, 'a4n3s>3n2Q>s>2n5')
          end

        end

      end
    end
  end
end