Add option to treat empty paragraphs as new line (#61)

Author: pranavbabu

README.md

@@ -78,6 +78,7 @@ Beside these options handled by Prawn / prawn-table, the following values may be
 - `:text`
   - `:preprocessor`: A proc/callable that is called each time before a chunk of text is rendered.
   - `:margin_bottom`: Margin after each `<p>`, `<ol>`, `<ul>` or `<table>`. Defaults to about half a line.
+  - `:treat_empty_paragraph_as_new_line`: Boolean flag to set a new line if paragraph is empty.
 - `:heading1-6`
   - `:margin_top`: Margin before a heading. Default is 0.
   - `:margin_bottom`: Margin after a heading. Default is 0.

lib/prawn/markup/processor/blocks.rb

@@ -63,11 +63,11 @@ def append_new_line
       def add_paragraph
         text = dump_text
         text.gsub!(/[^\n]/, '') if text.strip.empty?
-        unless text.empty?
-          add_bottom_margin
-          add_formatted_text(text, text_options)
-          put_bottom_margin(text_margin_bottom)
-        end
+        return if text.empty? && !treat_empty_paragraph_as_new_line?
+
+        add_bottom_margin
+        add_formatted_text(text.empty? ? "\n" : text, text_options)
+        put_bottom_margin(text_margin_bottom)
       end
 
       def add_current_text(options = text_options)
@@ -151,6 +151,10 @@ def default_text_options
           inline_format: true
         }
       end
+
+      def treat_empty_paragraph_as_new_line?
+        text_options[:treat_empty_paragraph_as_new_line] || false
+      end
     end
   end
 end

spec/prawn/markup/processor/blocks_spec.rb

@@ -84,7 +84,8 @@
           leading: leading,
           size: font_size,
           margin_bottom: 0,
-          preprocessor: ->(text) { text.upcase }
+          preprocessor: ->(text) { text.upcase },
+          treat_empty_paragraph_as_new_line: true
         }
       }
     end
@@ -107,5 +108,10 @@
       expect(top_positions).to eq([top, top - line].map(&:round))
     end
 
+    it "treats empty paragraphs as new line if configured" do
+      processor.parse("<p>hello</p><p></p><p>world</p>")
+      expect(text.strings).to eq(%w[HELLO WORLD])
+      expect(top_positions).to eq([top, top - 2 * line].map(&:round))
+    end
   end
 end