backport fix for support horizontal alignment on AsciiDoc table cell …

…that only contains paragraphs

CHANGELOG.adoc

@@ -11,6 +11,10 @@ Improvements::
 
 * replace OpenStruct with internal ThemeData class for storing theme data (#2535)
 
+Bug Fixes::
+
+* support horizontal alignment on AsciiDoc table cell that only contains paragraphs (#2358)
+
 == 2.3.18 (2024-07-27) - @mojavelinux
 
 Bug Fixes::

lib/asciidoctor/pdf/converter.rb

@@ -4745,7 +4745,8 @@ def admonition_icon_data key
       end
 
       def allocate_space_for_list_item line_metrics
-        advance_page if !at_page_top? && cursor < line_metrics.height + line_metrics.leading + line_metrics.padding_top
+        # need to check ancestors for table_cell as well; perhaps helper in_table_cell?
+        advance_page if !(bounds.instance_variable_get :@table_cell) && !at_page_top? && cursor < line_metrics.height + line_metrics.leading + line_metrics.padding_top
       end
 
       def apply_text_decoration styles, category, level = nil

lib/asciidoctor/pdf/ext/prawn-table/cell/asciidoc.rb

@@ -76,6 +76,7 @@ def draw_content
           padding_adjustment = content.context == :document ? padding_bottom : 0
           # NOTE: we've already reserved the space, so just let the box stretch to bottom of the content area
           pdf.bounds.instance_variable_set :@height, (pdf.y - pdf.page.margins[:bottom] - padding_adjustment)
+          pdf.bounds.instance_variable_set :@table_cell, true
           if @valign != :top && (excess_y = spanned_content_height - natural_content_height) > 0
             # QUESTION: could this cause a unexpected page overrun?
             pdf.move_down(@valign == :center ? (excess_y.fdiv 2) : excess_y)
@@ -92,6 +93,7 @@ def draw_content
           doc.catalog[:footnotes] = parent_doc.catalog[:footnotes]
           # TODO: apply horizontal alignment; currently it is necessary to specify alignment on content blocks
           apply_font_properties { pdf.traverse content }
+          pdf.bounds.remove_instance_variable :@table_cell
           if (extra_pages = pdf.page_number - start_page) > 0
             unless extra_pages == 1 && pdf.page.empty?
               logger.error message_with_context %(the table cell on page #{start_page} has been truncated; Asciidoctor PDF does not support table cell content that exceeds the height of a single page), source_location: @source_location
@@ -116,11 +118,16 @@ def apply_font_properties
             font_size = font_info[:size]
           end
           font_style ||= font_info[:style]
+          if (@align == :center || @align == :right) && content.blocks.map(&:context).uniq == [:paragraph]
+            prev_text_align = pdf.instance_variable_get :@base_text_align
+            pdf.instance_variable_set :@base_text_align, @align
+          end
           pdf.font font_family, size: font_size, style: font_style do
             yield
           ensure
             pdf.font_color = prev_font_color if prev_font_color
             pdf.font_scale = prev_font_scale if prev_font_scale
+            pdf.instance_variable_set :@base_text_align, prev_text_align if prev_text_align
           end
         end
       end

spec/table_spec.rb

@@ -1960,6 +1960,55 @@ def add_header(*)
       (expect pdf.lines).to eql ['10. ten', '11. eleven', '12. twelve', 'buckle', 'my', 'shoe']
     end
 
+    it 'should honor horizontal alignment on AsciiDoc table cell' do
+      pdf = to_pdf <<~'EOS', analyze: true
+      [cols=1a]
+      |===
+      |left
+      |===
+
+      [cols=^1a]
+      |===
+      |center
+      |===
+
+      [cols=>1a]
+      |===
+      |right
+      |===
+      EOS
+
+      page_width = pdf.pages[0][:size][0]
+      midpoint = page_width * 0.5
+      left_text = pdf.find_unique_text 'left'
+      center_text = pdf.find_unique_text 'center'
+      right_text = pdf.find_unique_text 'right'
+      (expect left_text[:x]).to be < midpoint
+      (expect center_text[:x]).to be < midpoint
+      (expect center_text[:x] + center_text[:width]).to be > midpoint
+      (expect right_text[:x]).to be > midpoint
+    end
+
+    it 'should not honor horizontal alignment on AsciiDoc table cell that contains non-paragraph blocks' do
+      pdf = to_pdf <<~'EOS', analyze: true
+      [cols=>1a]
+      |===
+      |
+      left
+
+      '''
+
+      left
+      |===
+      EOS
+
+      page_width = pdf.pages[0][:size][0]
+      midpoint = page_width * 0.5
+      left_texts = pdf.find_text 'left'
+      (expect left_texts[0][:x]).to be < midpoint
+      (expect left_texts[1][:x]).to be < midpoint
+    end
+
     it 'should convert nested table' do
       pdf = to_pdf <<~'EOS', analyze: true
       [cols="1,2a"]