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|
# frozen_string_literal: true
require_relative '../table'
module TTFunk
class Table
# Horizontal Header (`hhea`) table.
class Hhea < Table
# Table version
# @return [Integer]
attr_reader :version
# Typographic ascent.
# @return [Integer]
attr_reader :ascent
# Typographic descent.
# @return [Integer]
attr_reader :descent
# Typographic line gap.
# @return [Integer]
attr_reader :line_gap
# Maximum advance width value in `hmtx` table.
# @return [Integer]
attr_reader :advance_width_max
# Minimum left sidebearing value in `hmtx` table for glyphs with contours
# (empty glyphs should be ignored).
# @return [Integer]
attr_reader :min_left_side_bearing
# Minimum right sidebearing value.
# @return [Integer]
attr_reader :min_right_side_bearing
# Maximum extent.
# @return [Integer]
attr_reader :x_max_extent
# Caret slope rise.
# @return [Integer]
attr_reader :caret_slope_rise
# @deprecated Use {caret_slope_rise} instead.
# @!parse attr_reader :carot_slope_rise
# @return [Integer]
def carot_slope_rise
@caret_slope_rise
end
# Caret slope run.
# @return [Integer]
attr_reader :caret_slope_run
# @deprecated Use {caret_slope_run} instead.
# @!parse attr_reader :carot_slope_run
# @return [Integer]
def carot_slope_run
@caret_slope_run
end
# Caret offset.
# @return [Integer]
attr_reader :caret_offset
# Metric data format. `0` for current format.
# @return [Integer]
attr_reader :metric_data_format
# Number of hMetric entries in `hmtx` table.
# @return [Integer]
attr_reader :number_of_metrics
class << self
# Encode table.
#
# @param hhea [TTFunk::Table::Hhea] table to encode.
# @param hmtx [TTFunk::Table::Hmtx]
# @param original [TTFunk::File] original font file.
# @param mapping [Hash{Integer => Integer}] keys are new glyph IDs, values
# are old glyph IDs
# @return [String]
def encode(hhea, hmtx, original, mapping)
''.b.tap do |table|
table << [hhea.version].pack('N')
table << [
hhea.ascent, hhea.descent, hhea.line_gap,
*min_max_values_for(original, mapping),
hhea.caret_slope_rise, hhea.caret_slope_run, hhea.caret_offset,
0, 0, 0, 0, hhea.metric_data_format, hmtx[:number_of_metrics],
].pack('n*')
end
end
private
def min_max_values_for(original, mapping)
min_lsb = Min.new
min_rsb = Min.new
max_aw = Max.new
max_extent = Max.new
mapping.each_value do |old_glyph_id|
horiz_metrics = original.horizontal_metrics.for(old_glyph_id)
next unless horiz_metrics
min_lsb << horiz_metrics.left_side_bearing
max_aw << horiz_metrics.advance_width
glyph = original.find_glyph(old_glyph_id)
next unless glyph
x_delta = glyph.x_max - glyph.x_min
min_rsb << (horiz_metrics.advance_width - horiz_metrics.left_side_bearing - x_delta)
max_extent << (horiz_metrics.left_side_bearing + x_delta)
end
[
max_aw.value_or(0), min_lsb.value_or(0),
min_rsb.value_or(0), max_extent.value_or(0),
]
end
end
private
def parse!
@version = read(4, 'N').first
@ascent, @descent, @line_gap = read_signed(3)
@advance_width_max = read(2, 'n').first
@min_left_side_bearing, @min_right_side_bearing, @x_max_extent,
@caret_slope_rise, @caret_slope_run, @caret_offset,
_reserved, _reserved, _reserved, _reserved,
@metric_data_format = read_signed(11)
@number_of_metrics = read(2, 'n').first
end
end
end
end
|
