resolves asciidoctor#1382 add support for capitalize text transform

CHANGELOG.adoc

@@ -8,6 +8,7 @@ For a detailed view of what has changed, refer to the {uri-repo}/commits/master[
 == Unreleased
 
 * hyphenate prose using the text-hyphen gem if the `hyphens` attribute is set (#20)
+* add support for capitalize text transform (#1382)
 * fix AsciiDoc table cell from overflowing bounds of table and creating extra page (#1369)
 * don't double escape XML special characters in literal table cell (#1370)
 * use same line height throughout abstract

docs/theming-guide.adoc

@@ -465,6 +465,7 @@ The following transforms are recognized:
 
 * uppercase
 * lowercase
+* capitalize (each word, like CSS)
 * none (clears an inherited value)
 
 [CAUTION#transform-unicode-letters]
@@ -480,8 +481,6 @@ or
  $ gem install unicode
 ====
 
-// Additional transforms, such as capitalize, may be added in the future.
-
 === Colors
 
 The theme language supports color values in three formats:
@@ -1502,7 +1501,7 @@ The keys in this category control the style of most headings, including part tit
 |<<text-transforms,Text transform>> +
 (default: _inherit_)
 |heading:
-  text-transform: uppercase
+  text-transform: capitalize
 
 |line-height
 |<<values,Number>> +
@@ -1591,7 +1590,7 @@ The keys in this category control the style of most headings, including part tit
 |<<text-transforms,Text transform>> +
 (default: $heading-text-transform)
 |heading:
-  h3-text-transform: lowercase
+  h3-text-transform: uppercase
 
 |margin-top
 |<<measurement-units,Measurement>> +

lib/asciidoctor/pdf/ext/prawn/extensions.rb

@@ -431,6 +431,8 @@ def transform_text text, transform
       uppercase_pcdata text
     when :lowercase, 'lowercase'
       lowercase_mb text
+    when :capitalize, 'capitalize'
+      capitalize_words_pcdata text
     else
       text
     end

lib/asciidoctor/pdf/text_transformer.rb

@@ -25,6 +25,18 @@ def uppercase_pcdata string
     end
   end
 
+  def capitalize_words_pcdata string
+    if XMLMarkupRx.match? string
+      string.gsub(PCDATAFilterRx) { $2 ? (capitalize_words_mb $2) : $1 }
+    else
+      captialize_words_mb string
+    end
+  end
+
+  def capitalize_words_mb string
+    string.gsub(WordRx) { capitalize_mb $& }
+  end
+
   if RUBY_VERSION >= '2.4'
     def uppercase_mb string
       string.upcase
@@ -33,6 +45,10 @@ def uppercase_mb string
     def lowercase_mb string
       string.downcase
     end
+
+    def capitalize_mb string
+      string.capitalize
+    end
   # NOTE Unicode library is 4x as fast as ActiveSupport::MultiByte::Chars
   elsif defined? ::Unicode
     def uppercase_mb string
@@ -42,6 +58,10 @@ def uppercase_mb string
     def lowercase_mb string
       string.ascii_only? ? string.downcase : (::Unicode.downcase string)
     end
+
+    def lowercase_mb string
+      string.ascii_only? ? string.capitalize : (::Unicode.capitalize string)
+    end
   elsif defined? ::ActiveSupport::Multibyte
     MultibyteChars = ::ActiveSupport::Multibyte::Chars
 
@@ -52,6 +72,10 @@ def uppercase_mb string
     def lowercase_mb string
       string.ascii_only? ? string.downcase : (MultibyteChars.new string).downcase.to_s
     end
+
+    def capitalize_mb string
+      string.ascii_only? ? string.capitalize : (MultibyteChars.new string).capitalize.to_s
+    end
   else
     def uppercase_mb string
       string.upcase
@@ -60,6 +84,10 @@ def uppercase_mb string
     def lowercase_mb string
       string.downcase
     end
+
+    def capitalize_mb string
+      string.capitalize
+    end
   end
 
   def hyphenate_pcdata string, hyphenator

spec/text_formatter_spec.rb

@@ -167,6 +167,24 @@
       (expect lines[0]).to eql %(\uf085 Heading)
       (expect lines[1]).to eql %(See \uf085 Heading.)
     end
+
+    it 'should apply text transform to text' do
+      [
+        ['uppercase', 'here we go *again*', 'HERE WE GO AGAIN'],
+        ['lowercase', 'Here We Go *Again*', 'here we go again'],
+        ['capitalize', 'Here we go *again*', 'Here We Go Again'],
+      ].each do |(transform, before, after)|
+        pdf = to_pdf <<~EOS, pdf_theme: { heading_text_transform: transform }, analyze: true
+        == #{before}
+        EOS
+
+        lines = pdf.lines
+        (expect lines).to have_size 1
+        (expect lines[0]).to eql after
+        formatted_word = (pdf.find_text %r/again/i)[0]
+        (expect formatted_word[:font_name]).to eql 'NotoSerif-Bold'
+      end
+    end
   end
 
   context 'Roles' do