class Prawn::FontMetricCache

Cache used internally by Prawn::Document instances to calculate the width of various strings for layout purposes.

@private

Constants

CacheEntry

Public Class Methods

new(document) click to toggle source
# File lib/prawn/font_metric_cache.rb, line 16
def initialize(document)
  @document = document

  @cache = {}
end

Public Instance Methods

width_of(string, options) click to toggle source
# File lib/prawn/font_metric_cache.rb, line 22
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]

  length +
    (@document.character_spacing *
     @document.font.character_count(encoded_string))
end