Don’t set font on fragments without font when processing fallback #263

[petesharum]

The issue comes from the difference in how Prawn::Text::Formatted::Box and Prawn::Text handle styles. The fragments that are passed from Prawn::Text to Prawn::Text::Formatted::Box don't specify a font, relying on the font set on the document. After Prawn::Text::Formatted::Box#analyze_glyphs_for_fallback_support, the fragments are rewritten with font families specified but no styles. This patch preserves the original (:font-less) state for resulting fragments that don't require fallback.

Example that reproduces the issue (starting from example in manual):

    pdf_data = Prawn::Document.new do
      fallback_fonts ["Times-Roman"]

      ["Courier", "Helvetica", "Times-Roman"].each do |example_font|
        move_down 20

        [:bold, :bold_italic, :italic, :normal].each do |style|
          font example_font, :style => style do
            text "I'm writing in #{example_font} (#{style})"
          end
        end
      end
    end

In this version, styles have no effect. Commenting fallback_fonts ["Times-Roman"] shows the styles working.

[practicingruby]

Thanks. I'm going to need to do some homework and remind myself of how our fallback font system is supposed to work, but this patch has a reproducible error and a test, so I'll certainly try to review it in time for the next release, if not sooner.

[practicingruby]

Thanks for the patch. Because your pull request was accepted, you now have commit access to Prawn. Please see our contributor guidelines, and happy hacking!