Add support for the PlantUML Smetana layout engine

CHANGELOG.adoc

@@ -1,5 +1,11 @@
 = Asciidoctor-diagram Changelog
 
+== 2.2.18
+
+Enhancements::
+
+* Add opt-in support for the PlantUML Smetana layout engine
+
 == 2.2.17
 
 Bugfixes::

docs/modules/ROOT/pages/diagram_types/plantuml.adoc

@@ -21,4 +21,5 @@ It is particularly well-suited for users who prefer a simple, text-based approac
 |size-limit      |4096            |The maximum dimensions (width and height) of generated diagrams.
 |includedir      |unspecified     |sets a common directory for puml includes (plantuml.include.path)
 |preprocess      |true            |Preprocess PlantUML code before rendering the diagram.
+|options       |unspecified   |a comma separate list of flags that modify the image rendering. Currently only `smetana` is supported which enables the Smetana layout engine.
 |===

lib/asciidoctor-diagram/plantuml/converter.rb

@@ -37,9 +37,11 @@ def supported_formats
 
       def collect_options(source)
         options = {
-            :size_limit => source.attr('size-limit', '4096')
+            :size_limit => source.attr('size-limit', '4096'),
         }
 
+        options[:smetana] = true if source.opt('smetana')
+
         theme = source.attr('theme', nil)
         options[:theme] = theme if theme
 
@@ -106,9 +108,13 @@ def convert(source, format, options)
         add_theme_header(headers, options[:theme])
         add_size_limit_header(headers, options[:size_limit])
 
-        dot = source.find_command('dot', :alt_attrs => ['graphvizdot'], :raise_on_error => false)
-        if dot
-          headers['X-Graphviz'] = ::Asciidoctor::Diagram::Platform.host_os_path(dot)
+        if options[:smetana]
+          headers['X-Graphviz'] = 'smetana'
+        else
+          dot = source.find_command('dot', :alt_attrs => ['graphvizdot'], :raise_on_error => false)
+          if dot
+            headers['X-Graphviz'] = ::Asciidoctor::Diagram::Platform.host_os_path(dot)
+          end
         end
 
         response = Java.send_request(

spec/plantuml_spec.rb

@@ -835,4 +835,28 @@ class {child-class}
     expect(b.attributes['width']).to_not be_nil
     expect(b.attributes['height']).to_not be_nil
   end
+
+  it 'should support the Smetana layout engine' do
+    doc = <<-eos
+= Hello, Smetana!
+Doc Writer <doc@example.com>
+
+== First Section
+
+[plantuml, format="png", target="unscaled", opts="smetana"]
+----
+#{PLANTUML_CODE}
+----
+    eos
+
+    d = load_asciidoc doc, :attributes => {'backend' => 'html5'}
+    b = d.find { |bl| bl.context == :image }
+
+    target = b.attributes['target']
+    expect(target).to_not be_nil
+    expect(File.exist?(target)).to be true
+
+    expect(b.attributes['width']).to_not be_nil
+    expect(b.attributes['height']).to_not be_nil
+  end
 end