resolves #2193 fix size and position of full height inline image so it fits within available height of page

- always use bounds height as max height for inline image
- subtract top padding from line metrics from ascender for full height image
- don't protect bottom gutter if line contains a full height image
- add tests

6 files changed, 59 insertions, 7 deletions

diff --git a/CHANGELOG.adoc b/CHANGELOG.adoc
index 3d9d39c2..cd693bda 100644
--- a/CHANGELOG.adoc
+++ b/CHANGELOG.adoc
@@ -9,6 +9,7 @@ For a detailed view of what has changed, refer to the {url-repo}/commits/main[co
 
 Bug Fixes::
 
+* scale inline image to fit within available height of page, accounting for the top padding of the line and the bottom gutter (#2193)
 * short-circuit formatted_text routine and log error if fragments in first line cannot fit on a new page
 
 == 2.0.0 (2022-05-18) - @mojavelinux
diff --git a/lib/asciidoctor/pdf/ext/prawn/formatted_text/protect_bottom_gutter.rb b/lib/asciidoctor/pdf/ext/prawn/formatted_text/protect_bottom_gutter.rb
index 4b3ef5cd..a1a1e24b 100644
--- a/lib/asciidoctor/pdf/ext/prawn/formatted_text/protect_bottom_gutter.rb
+++ b/lib/asciidoctor/pdf/ext/prawn/formatted_text/protect_bottom_gutter.rb
@@ -2,12 +2,15 @@
 
 module Prawn::Text::Formatted::ProtectBottomGutter
   def enough_height_for_this_line?
-    return super unless @arranger.finished?
-    begin
-      @height -= @bottom_gutter
+    if @arranger.finished? && @arranger.fragments.none? {|it| it.format_state[:full_height] }
+      begin
+        @height -= @bottom_gutter
+        super
+      ensure
+        @height += @bottom_gutter
+      end
+    else
       super
-    ensure
-      @height += @bottom_gutter
     end
   end
 end
diff --git a/lib/asciidoctor/pdf/formatted_text/inline_image_arranger.rb b/lib/asciidoctor/pdf/formatted_text/inline_image_arranger.rb
index 2c23791c..e563a43a 100644
--- a/lib/asciidoctor/pdf/formatted_text/inline_image_arranger.rb
+++ b/lib/asciidoctor/pdf/formatted_text/inline_image_arranger.rb
@@ -38,7 +38,7 @@ module Asciidoctor::PDF::FormattedText
       return if (raw_image_fragments = fragments.select {|f| (f.key? :image_path) && !(f.key? :image_obj) }).empty?
       scratch = doc.scratch?
       available_w = available_width
-      available_h = doc.page.empty? ? doc.cursor : doc.bounds.height
+      available_h = doc.bounds.height
       last_fragment = {}
       raw_image_fragments.each do |fragment|
         if fragment[:object_id] == last_fragment[:object_id]
@@ -96,6 +96,10 @@ module Asciidoctor::PDF::FormattedText
           if (f_height = image_h) > (line_font = doc.font).height * 1.5
             # align with descender (equivalent to vertical-align: bottom in CSS)
             fragment[:ascender] = f_height - (fragment[:descender] = line_font.descender)
+            if f_height == available_h
+              fragment[:ascender] -= (doc.calc_line_metrics (doc.instance_variable_get :@base_line_height), line_font, doc.font_size).padding_top
+              fragment[:full_height] = true
+            end
             doc.font_size (fragment[:size] = f_height * (doc.font_size / line_font.height))
             # align with baseline (roughly equivalent to vertical-align: baseline in CSS)
             #fragment[:ascender] = f_height
diff --git a/spec/image_spec.rb b/spec/image_spec.rb
index d0b7a2ec..4305c2bb 100644
--- a/spec/image_spec.rb
+++ b/spec/image_spec.rb
@@ -507,7 +507,23 @@ describe 'Asciidoctor::PDF::Converter - Image' do
 
       pdf = to_pdf input, analyze: :line
       image_h = pdf.lines[1][:to][:y] - pdf.lines[1][:from][:y]
-      (expect image_h).to be_within(1).of(350)
+      (expect image_h).to eql 350.0
+    end
+
+    it 'should scale down inline SVG to fit height of next page' do
+      input = <<~'EOS'
+      :pdf-page-size: 200x350
+      :pdf-page-margin: 0
+
+      before
+
+      image:tall.svg[]
+      EOS
+
+      pdf = to_pdf input, analyze: :line
+      (expect pdf.lines.map {|it| it[:page_number] }.uniq).to eql [2]
+      image_h = pdf.lines[1][:to][:y] - pdf.lines[1][:from][:y]
+      (expect image_h).to eql 350.0
     end
 
     it 'should display text inside link' do
@@ -1615,6 +1631,34 @@ describe 'Asciidoctor::PDF::Converter - Image' do
       (expect line1_spacing).to eql line2_spacing
     end
 
+    it 'should scale image down to fit available height on next page', visual: true do
+      to_file = to_pdf_file <<~'EOS', 'image-inline-pushed-scale-down-height.pdf'
+      :pdf-page-size: A6
+      :pdf-page-layout: landscape
+
+      before
+
+      image:cover.jpg[]
+      EOS
+
+      to_file = to_pdf_file %(image::#{to_file}[page=2]), 'image-inline-pushed-scale-down-height-2.pdf'
+
+      (expect to_file).to visually_match 'image-inline-scale-down-height.pdf'
+    end
+
+    it 'should scale image down to fit available height inside delimited block', visual: true do
+      to_file = to_pdf_file <<~'EOS', 'image-inline-in-block-scale-down-height.pdf'
+      :pdf-page-size: A6
+      :pdf-page-layout: landscape
+
+      ****
+      image:cover.jpg[]
+      ****
+      EOS
+
+      (expect to_file).to visually_match 'image-inline-in-block-scale-down-height.pdf'
+    end
+
     it 'should not scale image if pdfwidth matches intrinsic width' do
       pdf = to_pdf <<~'EOS', analyze: :image
       see image:tux.png[pdfwidth=204] run
diff --git a/spec/reference/image-inline-in-block-scale-down-height.pdf b/spec/reference/image-inline-in-block-scale-down-height.pdf
new file mode 100644
index 00000000..1db693d4
--- /dev/null
+++ b/spec/reference/image-inline-in-block-scale-down-height.pdf
diff --git a/spec/reference/image-inline-scale-down-height.pdf b/spec/reference/image-inline-scale-down-height.pdf
index 562c1914..4cbc9a2f 100644
--- a/spec/reference/image-inline-scale-down-height.pdf
+++ b/spec/reference/image-inline-scale-down-height.pdf