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# frozen_string_literal: true
# font_metric_cache.rb : The Prawn font class
#
# Copyright Dec 2012, Kenneth Kalmer. All Rights Reserved.
#
# This is free software. Please see the LICENSE and COPYING files for details.
#
module Prawn
# Cache used internally by Prawn::Document instances to calculate the width
# of various strings for layout purposes.
#
# @private
class FontMetricCache
CacheEntry = Struct.new(:font, :options, :string)
def initialize(document)
@document = document
@cache = {}
end
def width_of(string, options)
f = if options[:style]
# override style with :style => :bold
@document.find_font(@document.font.family, style: options[:style])
else
@document.font
end
encoded_string = f.normalize_encoding(string)
key = CacheEntry.new(f, options, encoded_string)
@cache[key] ||= f.compute_width_of(encoded_string, options)
length = @cache[key]
character_count = @document.font.character_count(encoded_string)
if character_count.positive?
length += @document.character_spacing * (character_count - 1)
end
length
end
end
end
|
