Merge pull request #29 from blocknotes/adjust-font-spacing

Adjust spacing

Author: blocknotes

examples/headings.pdf

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 module PrawnHtml
+  ADJUST_LEADING = { nil => 0.18, 'Courier' => -0.07, 'Helvetica' => -0.17, 'Times-Roman' => 0.03 }.freeze
   PX = 0.6 # conversion constant for pixel sixes
 
   COLORS = {

examples/misc_elements.pdf

@@ -67,10 +67,17 @@ def remove_last
       last.on_context_remove(self) if last.respond_to?(:on_context_remove)
       @merged_styles = nil
       @last_text_node = false
-      @previous_tag = last.tag
+      @previous_tag = last
       pop
     end
 
+    # White space is equal to 'pre'?
+    #
+    # @return [boolean] white space property of the last element is equal to 'pre'
+    def white_space_pre?
+      last && last.styles[:white_space] == :pre
+    end
+
     private
 
     def evaluate_element_styles(element, res)

examples/random_content.pdf

@@ -12,6 +12,8 @@ def initialize(pdf)
       @buffer = []
       @context = Context.new
       @last_margin = 0
+      @last_text = ''
+      @last_tag_open = false
       @pdf = pdf
     end
 
@@ -22,6 +24,8 @@ def on_tag_close(element)
       render_if_needed(element)
       apply_tag_close_styles(element)
       context.remove_last
+      @last_tag_open = false
+      @last_text = ''
     end
 
     # On tag open callback
@@ -38,6 +42,7 @@ def on_tag_open(tag_name, attributes:, element_styles: '')
       options = { width: pdf.page_width, height: pdf.page_height }
       tag_class.new(tag_name, attributes: attributes, options: options).tap do |element|
         setup_element(element, element_styles: element_styles)
+        @last_tag_open = true
       end
     end
 
@@ -47,9 +52,10 @@ def on_tag_open(tag_name, attributes:, element_styles: '')
     #
     # @return [NilClass] nil value (=> no element)
     def on_text_node(content)
-      return if content.match?(/\A\s*\Z/)
+      return if context.previous_tag&.block? && content.match?(/\A\s*\Z/)
 
-      buffer << context.merged_styles.merge(text: prepare_text(content))
+      text = prepare_text(content)
+      buffer << context.merged_styles.merge(text: text) unless text.empty?
       context.last_text_node = true
       nil
     end
@@ -70,17 +76,13 @@ def render
     attr_reader :buffer, :context, :last_margin, :pdf
 
     def setup_element(element, element_styles:)
-      add_space_if_needed unless render_if_needed(element)
+      render_if_needed(element)
       context.add(element)
       element.process_styles(element_styles: element_styles)
       apply_tag_open_styles(element)
       element.custom_render(pdf, context) if element.respond_to?(:custom_render)
     end
 
-    def add_space_if_needed
-      buffer << SPACE if buffer.any? && !context.last_text_node && ![NEW_LINE, SPACE].include?(buffer.last)
-    end
-
     def render_if_needed(element)
       render_needed = element&.block? && buffer.any? && buffer.last != NEW_LINE
       return false unless render_needed
@@ -104,10 +106,12 @@ def apply_tag_open_styles(element)
     end
 
     def prepare_text(content)
-      white_space_pre = context.last && context.last.styles[:white_space] == :pre
-      text = ::Oga::HTML::Entities.decode(context.before_content)
-      text += white_space_pre ? content : content.gsub(/\A\s*\n\s*|\s*\n\s*\Z/, '').delete("\n").squeeze(' ')
-      text
+      text = context.before_content ? ::Oga::HTML::Entities.decode(context.before_content) : ''
+      return (@last_text = text + content) if context.white_space_pre?
+
+      content = content.lstrip if @last_text[-1] == ' ' || @last_tag_open
+      text += content.tr("\n", ' ').squeeze(' ')
+      @last_text = text
     end
 
     def output_content(buffer, block_styles)
@@ -129,7 +133,10 @@ def apply_callbacks(buffer)
     def adjust_leading(buffer, leading)
       return leading if leading
 
-      (buffer.map { |item| item[:size] || Context::DEFAULT_STYLES[:size] }.max * 0.055).round(4)
+      leadings = buffer.map do |item|
+        (item[:size] || Context::DEFAULT_STYLES[:size]) * (ADJUST_LEADING[item[:font]] || ADJUST_LEADING[nil])
+      end
+      leadings.max.round(4)
     end
 
     def bounds(buffer, options, block_styles)

examples/styles.pdf

@@ -12,7 +12,7 @@ def block?
       end
 
       def custom_render(pdf, context)
-        return if context.last_text_node || context.previous_tag != :br
+        return if context.last_text_node || !context.previous_tag.is_a?(Br)
 
         pdf.advance_cursor(BR_SPACING)
       end

lib/prawn-html.rb

@@ -3,8 +3,8 @@
 module TestUtils
   extend self
 
-  def adjust_leading(size = PrawnHtml::Context::DEFAULT_STYLES[:size])
-    (size * 0.055).round(4)
+  def adjust_leading(size = PrawnHtml::Context::DEFAULT_STYLES[:size], font = nil)
+    (size * PrawnHtml::ADJUST_LEADING[font]).round(4)
   end
 
   def default_font

lib/prawn_html/context.rb

@@ -110,7 +110,7 @@ def on_context_remove(context)
     it 'removes the last element from the context', :aggregate_failures do
       expect { remove_last }.to(
         change(context, :size).from(1).to(0).and(
-          change(context, :previous_tag).from(nil).to(:some_tag)
+          change(context, :previous_tag).from(nil).to(tag)
         )
       )
       expect(tag).to have_received(:on_context_remove)
@@ -159,4 +159,22 @@ def update_styles(res)
       end
     end
   end
+
+  describe '#white_space_pre?' do
+    subject(:white_space_pre?) { context.white_space_pre? }
+
+    before do
+      context << instance_double(PrawnHtml::Tag, styles: {})
+    end
+
+    it { is_expected.to be_falsey }
+
+    context 'when the last element has white-space property set to pre' do
+      before do
+        context << instance_double(PrawnHtml::Tag, styles: { white_space: :pre })
+      end
+
+      it { is_expected.to be_truthy }
+    end
+  end
 end