resolves asciidoctor#2477 force color space to be set when setting up…

… graphic state for stamp

- map color_space from graphic state on repeater to color space of current page so color space is set properly
- remove obsolete workaround to set color space on pages with images

CHANGELOG.adoc

@@ -41,6 +41,7 @@ Improvements::
 
 Bug Fixes::
 
+* ensure color spaces are set on page before adding running content (#2477)
 * correctly map all icons from FontAwesome 4 (#2373)
 * resolve remote image in document title or section title with autogenerated ID
 * keep caret between items in menu macro with previous item if items wrap

lib/asciidoctor/pdf/converter.rb

@@ -1826,9 +1826,6 @@ def convert_image node, opts = {}
                 rendered_w = (svg_obj.resize height: (rendered_h = available_h)).output_width if rendered_h > available_h
               end
               add_dest_for_block node if node.id
-              # NOTE: workaround to fix Prawn not adding fill and stroke commands on page that only has an image;
-              # breakage occurs when running content (stamps) are added to page
-              update_colors if graphic_state.color_space.empty?
               ink_caption node, category: :image, end: :top, block_align: alignment, block_width: rendered_w, max_width: caption_max_width if caption_end == :top && node.title?
               image_y = y
               left = bounds.left
@@ -1867,9 +1864,6 @@ def convert_image node, opts = {}
                 rendered_w = (image_info.calc_image_dimensions height: (rendered_h = available_h))[0] if rendered_h > available_h
               end
               add_dest_for_block node if node.id
-              # NOTE: workaround to fix Prawn not adding fill and stroke commands on page that only has an image;
-              # breakage occurs when running content (stamps) are added to page
-              update_colors if graphic_state.color_space.empty?
               ink_caption node, category: :image, end: :top, block_align: alignment, block_width: rendered_w, max_width: caption_max_width if caption_end == :top && node.title?
               image_y = y
               left = bounds.left
@@ -3608,7 +3602,16 @@ def ink_running_content periphery, doc, skip = [1, 1], body_start_page_number =
 
         pagenums_enabled = doc.attr? 'pagenums'
         periphery_layout_cache = {}
-        # NOTE: this block is invoked during PDF generation, after #write -> #render_file and thus after #convert_document
+        # NOTE: Prawn fails to properly set color spaces on empty pages, but repeater relies on them
+        # prefer simpler fix below call to repeat; keep this workaround in case that workaround stops working
+        #(content_start_page_number..num_pages).each do |pgnum|
+        #  next if (disable_on_pages.include? pgnum) || (pg = state.pages[pgnum - 1]).imported_page? || !pg.graphic_state.color_space.empty?
+        #  go_to_page pgnum
+        #  set_color_space :fill, (color_space graphic_state.fill_color)
+        #  set_color_space :stroke, (color_space graphic_state.stroke_color)
+        #end
+        #go_to_page content_start_page_number if page_number != content_start_page_number
+        # NOTE: this block is invoked during PDF generation, during call to #write -> #render_file and thus after #convert_document
         repeat (content_start_page_number..num_pages), dynamic: true do
           pgnum = page_number
           # NOTE: don't write on pages which are imported / inserts (otherwise we can get a corrupt PDF)
@@ -3719,7 +3722,11 @@ def ink_running_content periphery, doc, skip = [1, 1], body_start_page_number =
             end
           end
         end
-
+        # NOTE: force repeater to consult color spaces on current page instead of the page on which repeater was created
+        # if this stops working, use the commented code above repeat call instead
+        unless (repeater_graphic_state = repeaters[-1].instance_variable_get :@graphic_state).singleton_methods.include? :color_space
+          repeater_graphic_state.define_singleton_method :color_space, &(method :page_color_space)
+        end
         go_to_page prev_page_number
         nil
       end
@@ -4413,7 +4420,6 @@ def stamp_foreground_image doc, has_front_cover
 
       def start_new_chapter chapter
         start_new_page unless at_page_top?
-        # TODO: must call update_colors before advancing to next page if start_new_page is called in ink_chapter_title
         start_new_page if @ppbook && verso_page? && !(chapter.option? 'nonfacing')
       end
 
@@ -5093,6 +5099,10 @@ def on_image_error _reason, node, target, opts
         nil
       end
 
+      def page_color_space
+        page.graphic_state.color_space
+      end
+
       def remove_tmp_files
         @tmp_files.reject! {|_, path| path ? (unlink_tmp_file path) : true }
       end

spec/image_spec.rb

@@ -1176,7 +1176,18 @@ def traverse node
 
         (expect pdf.pages).to have_size 3
         page_contents = pdf.objects[(pdf.page 2).page_object[:Contents]].data
-        (expect (page_contents.split ?\n).slice 0, 3).to eql ['q', '/DeviceRGB cs', '0.0 0.0 0.0 scn']
+        page_content_lines = page_contents.split ?\n
+        (expect page_content_lines.shift).to eql 'q'
+        (expect page_content_lines.shift).to eql 'q'
+        stack_size = 1
+        until (line = page_content_lines.shift).nil?
+          if line == 'q'
+            stack_size += 1
+          elsif line == 'Q'
+            break if (stack_size -= 1) == 0
+          end
+        end
+        (expect page_content_lines.slice 0, 3).to eql ['q', '/DeviceRGB cs', '0.0 0.0 0.0 scn']
       end
     end
 
@@ -1399,7 +1410,19 @@ def traverse node
 
       (expect pdf.pages).to have_size 3
       page_contents = pdf.objects[(pdf.page 2).page_object[:Contents]].data
-      (expect (page_contents.split ?\n).slice 0, 3).to eql ['q', '/DeviceRGB cs', '0.0 0.0 0.0 scn']
+      page_content_lines = page_contents.split ?\n
+      (expect page_content_lines.shift).to eql 'q'
+      page_content_lines.shift if page_content_lines[0].empty?
+      (expect page_content_lines.shift).to eql 'q'
+      stack_size = 1
+      until (line = page_content_lines.shift).nil?
+        if line == 'q'
+          stack_size += 1
+        elsif line == 'Q'
+          break if (stack_size -= 1) == 0
+        end
+      end
+      (expect page_content_lines.slice 0, 3).to eql ['q', '/DeviceRGB cs', '0.0 0.0 0.0 scn']
     end
 
     it 'should place raster image in correct column when page columns are enabled' do

spec/media_spec.rb

@@ -160,5 +160,30 @@
       chapter_text = (pdf.find_text 'Chapter')[0]
       (expect chapter_text[:page_number]).to be 2
     end
+
+    it 'should initialize color space on empty verso pages', cli: true do
+      to_file = to_pdf_file <<~'END', 'running-content-on-empty-verso-pages.pdf', enable_footer: true
+      = Document Title
+      :doctype: book
+      :media: prepress
+
+      == Beginning
+
+      content
+
+      == Middle
+
+      content
+
+      == End
+
+      content
+      END
+
+      out, err, res = run_command 'pdftotext', to_file, '-'
+      (expect res.exitstatus).to be 0
+      (expect out).to include '4'
+      (expect err).to be_empty
+    end
   end
 end

spec/running_content_spec.rb

@@ -35,6 +35,14 @@
       END
       (expect pdf.pages).to have_size 3
       (expect pdf.pages[1].text).to eql '2'
+      pdf.pages.each do |page|
+        contents = pdf.objects[page.page_object[:Contents]].data
+        content_lines = contents.lines
+        before_fill_color = (content_lines.slice 0, content_lines.index {|it| it.end_with? %( scn\n) }).join
+        before_stroke_color = (content_lines.slice 0, content_lines.index {|it| it.end_with? %( SCN\n) }).join
+        (expect before_fill_color).to include %(\n/DeviceRGB cs\n)
+        (expect before_stroke_color).to include %(\n/DeviceRGB CS\n)
+      end
     end
 
     it 'should start adding running content to page after imported page' do