如何使用多种字体，即HexaPDF中的复合字体

gem install hexapdf

require 'hexapdf'

doc = HexaPDF::Document.new

regular_font_path = 'path/to/regular_font.ttf'
bold_font_path = 'path/to/bold_font.ttf'

regular_font = doc.fonts.add_file(regular_font_path)
bold_font = doc.fonts.add_file(bold_font_path)

composite_font = doc.fonts.add(composite: true)
composite_font.add_regular_font(regular_font)
composite_font.add_bold_font(bold_font)

text = 'Hello, World!'
font_size = 12

doc.pages.add([0, 0, 200, 100]).canvas do |canvas|
  canvas.font(composite_font, size: font_size)
  canvas.text(text, at: [50, 50])
end

doc.write('output.pdf')