resolves #1918 prepress page margins should honor value of pdf-folio-placement (PR #2058)

3 files changed, 70 insertions, 19 deletions

diff --git a/CHANGELOG.adoc b/CHANGELOG.adoc
index f167d758..a3277d1b 100644
--- a/CHANGELOG.adoc
+++ b/CHANGELOG.adoc
@@ -193,6 +193,7 @@ Bug Fixes::
 * don't render borders and backgrounds in scratch document
 * don't insert blank page after document title if first block (chapter or toc macro) has nonfacing option (#1988)
 * coerce negated variable reference to number if value of variable is numeric
+* prepress page margins should honor value of `pdf-folio-placement` (#1918)
 
 Compliance::
 
diff --git a/lib/asciidoctor/pdf/converter.rb b/lib/asciidoctor/pdf/converter.rb
index 38fd9747..dbcef793 100644
--- a/lib/asciidoctor/pdf/converter.rb
+++ b/lib/asciidoctor/pdf/converter.rb
@@ -354,8 +354,19 @@ module Asciidoctor
         #@page_opts = { size: pdf_opts[:page_size], layout: pdf_opts[:page_layout] }
         ((::Prawn::Document.instance_method :initialize).bind self).call pdf_opts
         renderer.min_version (@pdf_version = PDFVersions[doc.attr 'pdf-version'])
+        @media = doc.attr 'media', 'screen'
         @page_margin_by_side = { recto: (page_margin_recto = page_margin), verso: (page_margin_verso = page_margin), cover: page_margin }
-        if (@media = doc.attr 'media', 'screen') == 'prepress'
+        case doc.attr 'pdf-folio-placement', (@media == 'prepress' ? 'physical' : 'virtual')
+        when 'physical'
+          @folio_placement = { basis: :physical }
+        when 'physical-inverted'
+          @folio_placement = { basis: :physical, inverted: true }
+        when 'virtual-inverted'
+          @folio_placement = { basis: :virtual, inverted: true }
+        else
+          @folio_placement = { basis: :virtual }
+        end
+        if @media == 'prepress'
           @ppbook = doc.doctype == 'book'
           if (page_margin_outer = theme.page_margin_outer)
             page_margin_recto[1] = page_margin_verso[3] = page_margin_outer
@@ -605,15 +616,15 @@ module Asciidoctor
       # NOTE: init_page is called within a float context; this will suppress prawn-svg messing with the cursor
       # NOTE: init_page is not called for imported pages, front and back cover pages, and other image pages
       def init_page *_args
-        # NOTE: we assume in prepress that physical page number reflects page side
-        if @media == 'prepress' && (next_page_margin = @page_margin_by_side[page_number == 1 ? :cover : page_side]) != page_margin
+        next_page_side = page_side nil, @folio_placement[:inverted]
+        if @media == 'prepress' && (next_page_margin = @page_margin_by_side[page_number == 1 ? :cover : next_page_side]) != page_margin
           set_page_margin next_page_margin
         end
         unless @page_bg_color == 'FFFFFF'
           tare = true
           fill_absolute_bounds @page_bg_color
         end
-        if (bg_image_path, bg_image_opts = @page_bg_image[page_side])
+        if (bg_image_path, bg_image_opts = @page_bg_image[next_page_side])
           tare = true
           begin
             if bg_image_opts[:format] == 'pdf'
@@ -624,9 +635,9 @@ module Asciidoctor
               canvas { image bg_image_path, ({ position: :center, vposition: :center }.merge bg_image_opts) }
             end
           rescue
-            facing_page_side = (PageSides - [page_side])[0]
-            @page_bg_image[facing_page_side] = nil if @page_bg_image[facing_page_side] == @page_bg_image[page_side]
-            @page_bg_image[page_side] = nil
+            facing_page_side = (PageSides - [next_page_side])[0]
+            @page_bg_image[facing_page_side] = nil if @page_bg_image[facing_page_side] == @page_bg_image[next_page_side]
+            @page_bg_image[next_page_side] = nil
             log :warn, %(could not embed page background image: #{bg_image_path}; #{$!.message})
           end
         end
@@ -2696,7 +2707,7 @@ module Asciidoctor
           start_new_page
         end
 
-        side = recycle ? page_side : (page_side page_number + 1)
+        side = page_side (recycle ? nil : page_number + 1), @folio_placement[:inverted]
         prev_bg_image = @page_bg_image[side]
         prev_bg_color = @page_bg_color
         if (bg_image = resolve_background_image doc, @theme, 'title-page-background-image')
@@ -3313,16 +3324,6 @@ module Asciidoctor
         doc.set_attr 'page-count', (num_pages - skip_pagenums)
 
         pagenums_enabled = doc.attr? 'pagenums'
-        case doc.attr 'pdf-folio-placement', (@media == 'prepress' ? 'physical' : 'virtual')
-        when 'physical'
-          folio_basis, invert_folio = :physical, false
-        when 'physical-inverted'
-          folio_basis, invert_folio = :physical, true
-        when 'virtual-inverted'
-          folio_basis, invert_folio = :virtual, true
-        else
-          folio_basis, invert_folio = :virtual, false
-        end
         periphery_layout_cache = {}
         # NOTE: this block is invoked during PDF generation, after #write -> #render_file and thus after #convert_document
         repeat (content_start_page..num_pages), dynamic: true do
@@ -3331,7 +3332,7 @@ module Asciidoctor
           next if page.imported_page? || (disable_on_pages.include? pgnum)
           virtual_pgnum = pgnum - skip_pagenums
           pgnum_label = (virtual_pgnum < 1 ? (RomanNumeral.new pgnum, :lower) : virtual_pgnum).to_s
-          side = page_side((folio_basis == :physical ? pgnum : virtual_pgnum), invert_folio)
+          side = page_side((@folio_placement[:basis] == :physical ? pgnum : virtual_pgnum), @folio_placement[:inverted])
           doc.set_attr 'page-layout', page.layout.to_s
 
           # NOTE: running content is cached per page layout
diff --git a/spec/page_spec.rb b/spec/page_spec.rb
index 80b87627..baa66ca4 100644
--- a/spec/page_spec.rb
+++ b/spec/page_spec.rb
@@ -487,6 +487,55 @@ describe 'Asciidoctor::PDF::Converter - Page' do
 
       (expect to_file).to visually_match 'page-prepress-margins-body-only.pdf'
     end
+
+    it 'should invert recto/verso margins when pdf-folio-placement is inverted' do
+      pdf_theme = {
+        page_margin_inner: 72,
+        page_margin_outer: 54,
+        footer_recto_right_content: nil,
+        footer_recto_left_content: 'page {page-number}',
+        footer_verso_right_content: nil,
+        footer_verso_left_content: 'p{page-number}',
+        footer_padding: [6, 0, 0, 0],
+      }
+      pdf = to_pdf <<~'EOS', pdf_theme: pdf_theme, enable_footer: true, analyze: true
+      = Book Title
+      :media: prepress
+      :doctype: book
+      :pdf-folio-placement: physical-inverted
+
+      == First Chapter
+
+      content
+
+      <<<
+
+      more content
+
+      == Last Chapter
+
+      content
+      EOS
+
+      first_chapter_text = pdf.find_unique_text 'First Chapter'
+      (expect first_chapter_text[:page_number]).to eql 3
+      (expect first_chapter_text[:x]).to eql 54.0
+      pgnum_1_text = pdf.find_unique_text 'p1'
+      (expect pgnum_1_text[:x]).to eql 54.0
+      (expect pgnum_1_text[:page_number]).to eql 3
+      more_content_text = pdf.find_unique_text 'more content'
+      (expect more_content_text[:x]).to eql 72.0
+      (expect more_content_text[:page_number]).to eql 4
+      pgnum_2_text = pdf.find_unique_text 'page 2'
+      (expect pgnum_2_text[:x]).to eql 72.0
+      (expect pgnum_2_text[:page_number]).to eql 4
+      last_chapter_text = pdf.find_unique_text 'Last Chapter'
+      (expect last_chapter_text[:x]).to eql 54.0
+      (expect last_chapter_text[:page_number]).to eql 5
+      pgnum_3_text = pdf.find_unique_text 'p3'
+      (expect pgnum_3_text[:x]).to eql 54.0
+      (expect pgnum_3_text[:page_number]).to eql 5
+    end
   end
 
   context 'Background' do