follow-up to #1745 to add support for % units as well

3 files changed, 21 insertions, 3 deletions

diff --git a/CHANGELOG.adoc b/CHANGELOG.adoc
index a2f69545..f2861b39 100644
--- a/CHANGELOG.adoc
+++ b/CHANGELOG.adoc
@@ -100,7 +100,7 @@ Bug Fixes::
 * display decimal list marker correctly when list is reversed (e.g., 10., 09., 08., etc)
 * use correct spacing for dotted border dash on table (length and spacing should match width)
 * set color space on page with only image so font color is preserved in running content (#1742)
-* compute font size for superscript and subscript correctly when parent element uses em units (#1745)
+* compute font size for superscript and subscript correctly when parent element uses em and % units (#1745)
 * respect hyphenation exceptions when word is adjacent to non-word character (#1715)
 * fix crash when TOC is enabled and index is empty
 * align TOC section properly when index exceeds one page and section_indent is positive (#1735)
diff --git a/lib/asciidoctor/pdf/ext/prawn/formatted_text/arranger.rb b/lib/asciidoctor/pdf/ext/prawn/formatted_text/arranger.rb
index a7831c21..4413fb0c 100644
--- a/lib/asciidoctor/pdf/ext/prawn/formatted_text/arranger.rb
+++ b/lib/asciidoctor/pdf/ext/prawn/formatted_text/arranger.rb
@@ -21,8 +21,12 @@ Prawn::Text::Formatted::Arranger.prepend (Module.new do
   def apply_font_size size, styles
     if (subscript? styles) || (superscript? styles)
       size ||= @document.font_size
-      units = (size.end_with? 'em') ? 'em' : '' if String === size
-      size = units ? %(#{size.to_f * SUB_N_SUP_RELATIVE_SIZE}#{units}) : size * SUB_N_SUP_RELATIVE_SIZE
+      if String === size
+        units = (size.end_with? 'em', '%') ? ((size.end_with? '%') ? '%' : 'em') : ''
+        size = %(#{size.to_f * SUB_N_SUP_RELATIVE_SIZE}#{units})
+      else
+        size *= SUB_N_SUP_RELATIVE_SIZE
+      end
       @document.font_size(size) { yield }
     elsif size
       @document.font_size(size) { yield }
diff --git a/spec/formatted_text_formatter_spec.rb b/spec/formatted_text_formatter_spec.rb
index 440856fe..3e28de87 100644
--- a/spec/formatted_text_formatter_spec.rb
+++ b/spec/formatted_text_formatter_spec.rb
@@ -184,6 +184,13 @@ describe Asciidoctor::PDF::FormattedText::Formatter do
       (expect superscript_text[:font_size]).to eql expected_font_size
     end
 
+    it 'should compute font size for superscript phrase correctly when parent element uses % units' do
+      pdf = to_pdf '`x^2^` represents exponential growth', pdf_theme: { base_font_size: 14, literal_font_size: '90%' }, analyze: true
+      expected_font_size = 14 * 0.9 * 0.583
+      superscript_text = pdf.find_unique_text '2'
+      (expect superscript_text[:font_size]).to eql expected_font_size
+    end
+
     it 'should format subscript phrase' do
       pdf = to_pdf 'O~2~', analyze: true
       (expect pdf.strings).to eql %w(O 2)
@@ -199,6 +206,13 @@ describe Asciidoctor::PDF::FormattedText::Formatter do
       (expect subscript_text[:font_size]).to eql expected_font_size
     end
 
+    it 'should compute font size for subscript phrase correctly when parent element uses % units' do
+      pdf = to_pdf 'The formula `O~2~` is oxygen', pdf_theme: { base_font_size: 14, literal_font_size: '90%' }, analyze: true
+      expected_font_size = 14 * 0.9 * 0.583
+      subscript_text = pdf.find_unique_text '2'
+      (expect subscript_text[:font_size]).to eql expected_font_size
+    end
+
     it 'should add background and border to code as defined in theme', visual: true do
       theme_overrides = {
         literal_background_color: 'f5f5f5',