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In our visualization, what we have is an instance of a Turing machine model, and what we want to end up with is a proper diagram that visualizes it. Of course, Lightweight Diagrams has not the slightest clue about what we want our diagrams to look like. That is where the synthesis, highlightes above, comes into play. The synthesis is what transforms an instance of our source model into a KGraph that Lightweight Diagrams knows how to render. (Along the way, KIELER Layout is invoked by KLighD to compute positions for all diagram elements.) However, the KGraph itself does not suffice to render the diagram: it only specifies its structure, but not its appearance. To specify the latter, we also need to augment our KGraph by KRendering information. See its documentation to learn more about what it can do.

Right, let's dive right in and develop our synthesis.

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/* Package and import statements... */

class TuringMachineDiagramSynthesis extends AbstractDiagramSynthesis<TuringMachine> {
    
    @Inject extension KNodeExtensions
    @Inject extension KEdgeExtensions
    @Inject extension KPortExtensions
    @Inject extension KLabelExtensions
    @Inject extension KRenderingExtensions
    @Inject extension KContainerRenderingExtensions
    @Inject extension KPolylineExtensions
    @Inject extension KColorExtensions
    extension KRenderingFactory = KRenderingFactory.eINSTANCE
    
    
    override KNode transform(TuringMachine model) {
        val root = model.createNode().associateWith(model);
        
        // Your dsl element <-> diagram figure mapping goes here!!
        
        return root;
    }
    
}

Note that this is not Java, but Xtend code. Xtend is a language that compiles to Java and has a bunch of nifty little features that make writing a synthesis easier. The main entry point of our synthesis is the transform method. As you can see, the method gets a TuringMachine instance and returns a KNode. That KNode will contain our actual diagram. Let's start by adding nodes for all states in the Turing machine.

1. Add a new method to your synthesis that transforms a State into a corresponding KNode:

   Code Block
   language java linenumbers true
   private def KNode createState(State state) { val stateNode = state.createNode().associateWith(state); return stateNode; }