resolves #1170 prevent table alignment from modifying margins of subs…

…equent pages (PR #1172)

CHANGELOG.adoc

@@ -13,6 +13,7 @@ For a detailed view of what has changed, refer to the {uri-repo}/commits/master[
 * fix crash when toc is enabled and toc-title attribute is unset
 * correctly map legacy Font Awesome icon names when icon set is not specified (#1157)
 * coerce color values in theme that contain uppercase letters (#1149)
+* prevent table alignment from modifying margins of subsequent pages; only align table if width is less than bounds (#1170)
 * ensure base font color is set
 * use more robust mechanism to detect an empty page; tare content stream after adding page background color or image
 * ignore pdf-themesdir unless pdf-theme is specified (#1167)

lib/asciidoctor-pdf/converter.rb

@@ -1966,7 +1966,8 @@ def convert_table node
 
     table_settings = {
       header: table_header,
-      position: alignment,
+      # NOTE position is handled by this method
+      position: :left,
       cell_style: {
         # NOTE the border color and style of the outer frame is set later
         border_color: table_grid_color,
@@ -1992,11 +1993,23 @@ def convert_table node
 
     theme_margin :block, :top
 
+    left_padding = right_padding = nil
     table table_data, table_settings do
       # NOTE call width to capture resolved table width
       table_width = width
       caption_max_width = caption_max_width == 'fit-content' ? table_width : nil
       @pdf.layout_table_caption node, alignment, caption_max_width if node.title? && caption_side == :top
+      # NOTE align using padding instead of bounding_box as prawn-table does
+      # using a bounding_box across pages mangles the margin box of subsequent pages
+      if alignment != :left && table_width != (this_bounds = @pdf.bounds).width
+        if alignment == :center
+          left_padding = right_padding = (this_bounds.width - width) * 0.5
+          this_bounds.add_left_padding left_padding
+          this_bounds.add_right_padding right_padding
+        else # :right
+          this_bounds.add_left_padding(left_padding = this_bounds.width - width)
+        end
+      end
       if grid == 'none' && frame == 'none'
         if table_header
           rows(0).tap do |r|
@@ -2055,6 +2068,10 @@ def convert_table node
         #end
       end
     end
+    if left_padding
+      bounds.subtract_left_padding left_padding
+      bounds.subtract_right_padding right_padding if right_padding
+    end
     layout_table_caption node, alignment, caption_max_width, caption_side if node.title? && caption_side == :bottom
     theme_margin :block, :bottom
   end

spec/table_spec.rb

@@ -521,5 +521,103 @@
 
       (expect cell_right[:x]).to be > cell_left[:x]
     end
+
+    it 'should allow position of table to be set using align attribute on table' do
+      pdf = to_pdf <<~'EOS', analyze: true
+      [cols=3*,width=50%]
+      |===
+      |LEFT |B1 |C1
+      |A2 |B2 |C2
+      |A3 |B3 |C3
+      |===
+
+      [cols=3*,width=50%,align=right]
+      |===
+      |RIGHT |B1 |C1
+      |A2 |B2 |C2
+      |A3 |B3 |C3
+      |===
+      EOS
+
+      cell_right_text = (pdf.find_text 'RIGHT')[0]
+      cell_left_text = (pdf.find_text 'LEFT')[0]
+
+      (expect cell_right_text[:x]).to be > cell_left_text[:x]
+    end
+
+    it 'should not mangle margin box on subsequent pages if table with alignment crosses page boundary' do
+      blank_line = %(\n\n)
+
+      pdf = to_pdf <<~EOS, analyze: true
+      #{(['filler'] * 25).join blank_line}
+
+      [%autowidth,align=right]
+      |===
+      |A | B
+
+      |A1
+      |B1
+
+      |A2
+      |B2
+
+      |A3
+      |B3
+      |===
+
+      #{(['filler'] * 22).join blank_line}
+
+      #{(['* list item'] * 6).join ?\n}
+      EOS
+
+      page_width = pdf.pages[0][:size][0]
+      a1_text = (pdf.find_text 'A1')[0]
+      a3_text = (pdf.find_text 'A3')[0]
+      (expect a1_text[:x]).to be > (page_width * 0.5)
+      (expect a1_text[:page_number]).to eql 1
+      (expect a3_text[:x]).to be > (page_width * 0.5)
+      (expect a3_text[:page_number]).to eql 2
+      first_list_item_text = (pdf.find_text string: 'list item', page_number: 2)[0]
+      last_list_item_text = (pdf.find_text string: 'list item', page_number: 3)[-1]
+      # NOTE if this is off, the margin box got mangled
+      (expect last_list_item_text[:x]).to eql first_list_item_text[:x]
+    end
+
+    it 'should set width of aligned table relative to bounds' do
+      pdf = to_pdf <<~EOS, analyze: true
+      [width=25%,align=right]
+      |===
+      |A | B
+
+      |A1
+      |B1
+
+      |A2
+      |B2
+      |===
+      ====
+      ****
+
+      [width=25%,align=right]
+      |===
+      |A | B
+
+      |A1
+      |B1
+
+      |A2
+      |B2
+      |===
+      ****
+      ====
+      EOS
+
+      page_width = pdf.pages[0][:size][0]
+      first_a1_text = (pdf.find_text 'A1')[0]
+      second_a1_text = (pdf.find_text 'A1')[1]
+      (expect first_a1_text[:x]).to be > (page_width * 0.5)
+      (expect second_a1_text[:x]).to be > (page_width * 0.5)
+      (expect first_a1_text[:x]).to be > second_a1_text[:x]
+    end
   end
 end