prawn:Prawn::Text::Box#height
#!/usr/bin/env ruby require "prawn" pdf = Prawn::Document.new box = Prawn::Text::Box.new("foo", :document => pdf) p box.height box.render p box.height box.render p box.height pdf.render_file(File.basename($0, ".rb") + ".pdf")
で、
0 11.1 11.1