Visitor

Starting with 3.0.0 visiting of parsed markdown nodes does not require creating own instance of commonmark-java Visitor, instead a composable/configurable MarkwonVisitor is used.

Visitor.Builder

There is no need to create own instance of MarkwonVisitor.Builder as it is done by Markwon itself. One still can configure it as one wishes:

final Markwon markwon = Markwon.builder(contex)
        .usePlugin(new AbstractMarkwonPlugin() {
            @Override
            public void configureVisitor(@NonNull MarkwonVisitor.Builder builder) {
                builder.on(SoftLineBreak.class, new MarkwonVisitor.NodeVisitor<SoftLineBreak>() {
                    @Override
                    public void visit(@NonNull MarkwonVisitor visitor, @NonNull SoftLineBreak softLineBreak) {
                        visitor.forceNewLine();
                    }
                });
            }
        });

MarkwonVisitor encapsulates most of the functionality of rendering parsed markdown.

It holds rendering configuration:

MarkwonVisitor#configuration - getter for current MarkwonConfiguration
MarkwonVisitor#renderProps - getter for current RenderProps
MarkwonVisitor#builder - getter for current SpannableBuilder

It contains also a number of utility functions:

visitChildren(Node) - will visit all children of supplied Node
hasNext(Node) - utility function to check if supplied Node has a Node after it (useful for white-space management, so there should be no blank new line after last BlockNode)
ensureNewLine - will insert a new line at current SpannableBuilder position only if current (last) character is not a new-line
forceNewLine - will insert a new line character without any condition checking
length - helper function to call visitor.builder().length(), returns current length of SpannableBuilder
clear - will clear state for RenderProps and SpannableBuilder, this is done by Markwon automatically after each render call

And some utility functions to control the spans:

setSpans(int start, Object spans) - will apply supplied spans on SpannableBuilder starting at start position and ending at SpannableBuilder#length. spans can be null (no spans will be applied) or an array of spans (each span of this array will be applied)
setSpansForNodeOptional(N node, int start) - helper method to set spans for specified node (internally obtains SpanFactory for that node and uses it to apply spans)
setSpansForNode(N node, int start) - almost the same as setSpansForNodeOptional but instead of silently ignoring call if none SpanFactory is registered, this method will throw an exception.

@Override
public void configureVisitor(@NonNull MarkwonVisitor.Builder builder) {
    builder.on(Heading.class, new MarkwonVisitor.NodeVisitor<Heading>() {
        @Override
        public void visit(@NonNull MarkwonVisitor visitor, @NonNull Heading heading) {

            // or just `visitor.length()`
            final int start = visitor.builder().length();

            visitor.visitChildren(heading);

            // or just `visitor.setSpansForNodeOptional(heading, start)`
            final SpanFactory factory = visitor.configuration().spansFactory().get(heading.getClass());
            if (factory != null) {
                visitor.setSpans(start, factory.getSpans(visitor.configuration(), visitor.renderProps()));
            }
            
            if (visitor.hasNext(heading)) {
                visitor.ensureNewLine();
                visitor.forceNewLine();
            }
        }
    });
}

BlockHandler 4.3.0

Since 4.3.0 there is class to control insertions of new lines after markdown blocks BlockHandler (MarkwonVisitor.BlockHandler) and its default implementation BlockHandlerDef. For example, to disable an empty new line after Heading:

final Markwon markwon = Markwon.builder(this)
        .usePlugin(new AbstractMarkwonPlugin() {
            @Override
            public void configureVisitor(@NonNull MarkwonVisitor.Builder builder) {
                builder.blockHandler(new BlockHandlerDef() {
                    @Override
                    public void blockEnd(@NonNull MarkwonVisitor visitor, @NonNull Node node) {
                        if (node instanceof Heading) {
                            if (visitor.hasNext(node)) {
                                visitor.ensureNewLine();
                                // ensure new line but do not force insert one
                            }
                        } else {
                            super.blockEnd(visitor, node);
                        }
                    }
                });
            }
        })
        .build();

# Visitor

# Visitor.Builder

# BlockHandler 4.3.0

Visitor

Visitor.Builder

BlockHandler 4.3.0