resolves #2538 don't allow AsciiDoc table cell to overrun bottom of p…

…age on which it fits (PR #2539)

CHANGELOG.adoc

@@ -54,6 +54,7 @@ Bug Fixes::
 * prevent special character substitution from interfering with callouts in plain verbatim block (#2390)
 * remove deprecated, undocumented `svg-font-family` theme key (the correct key is `svg-fallback-font-family`)
 * major improvement to OTF support following release of ttfunk 1.8.0 (automatic transitive dependency of prawn)
+* don't allow AsciiDoc table cell to overrun bottom of page on which it fits (#2538)
 
 == 2.3.18 (2024-07-27) - @mojavelinux
 

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

@@ -73,9 +73,8 @@ def draw_content
           end
           # NOTE: draw_bounded_content automatically adds FPTolerance to width and height
           pdf.bounds.instance_variable_set :@width, spanned_content_width
-          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)
+          # NOTE: we've already reserved the space, so just let the box stretch to the maximum that could fit on a page
+          pdf.bounds.instance_variable_set :@height, (pdf.margin_box.height - padding_top - padding_bottom)
           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)

spec/table_spec.rb

@@ -2749,6 +2749,65 @@ def add_header(*)
         end).to log_message severity: :ERROR, message: 'the table cell on page 1 has been truncated; Asciidoctor PDF does not support table cell content that exceeds the height of a single page'
       end
     end
+
+    it 'should reserve remaining space on page once cell is determined to fit' do
+      pdf_theme = {
+        extends: 'default',
+        page_layout: 'landscape',
+        page_margin: 56,
+        base_font_size: 10.5,
+        base_line_height: 1.5,
+        list_item_spacing: 0,
+        prose_margin_bottom: 6,
+        table_cell_padding: [3, 5],
+      }
+
+      input = <<~END
+      :pdf-page-layout: landscape
+      :nofooter:
+
+      .Table 1
+      [cols=a]
+      |===
+      | Row 1
+      | * 1
+      * 2
+      * 3
+      * 4
+      |===
+
+      .Table 2
+      [cols=a]
+      |===
+      | Row 1
+      | * 1
+      * 2
+      * 3
+      * 4
+      |===
+
+      .Table 3
+      [cols=a]
+      |===
+      | Row 1
+      | * 1
+      * 2
+      * 3
+      * 4
+      * 5
+      * second to last line
+      * last line
+      |===
+      END
+
+      pdf = nil
+      (expect do
+        pdf = to_pdf input, pdf_theme: pdf_theme, analyze: true
+      end).not_to log_message
+      last_line_text = pdf.find_unique_text 'last line'
+      (expect last_line_text).not_to be_nil
+      (expect last_line_text[:page_number]).to eql 1
+    end
   end
 
   context 'Caption' do