Possible to use this crate w/o IO?

[peekxc]

Hey thanks for this crate, it looks like it contains a variety of decently faithful implementations of many of the sub-algorithms necessary for a sugiyama / layered-graph layout.

Is it possible to use the underlying algorithms in this crate directly without inputting dot files and outputting SVG's? I have no need for either; it looks like it's possible to avoid the former by constructs the VisualGraph directly, as in the GraphBuilder examples:

    // Create a new graph:
    let mut vg = VisualGraph::new(Orientation::LeftToRight);

    // Define the node styles:
    let sp0 = ShapeKind::new_box("one");
    let sp1 = ShapeKind::new_box("two");
    let look0 = StyleAttr::simple();
    let look1 = StyleAttr::simple();
    let sz = Point::new(100., 100.);
    // Create the nodes:
    let node0 = Element::create(sp0, look0, Orientation::LeftToRight, sz);
    let node1 = Element::create(sp1, look1, Orientation::LeftToRight, sz);

But is it possible to extract various positioning information without using the SVGWriter backend?

    // Render the nodes to some rendering backend.
    let mut svg = SVGWriter::new();
    vg.do_it(false, false, false, &mut svg);

    // Save the output.
    let _ = save_to_file("/tmp/graph.svg", &svg.finalize());

I suppose I could avoid the save_to_file and inspect svg directly; I was more hoping for something more basic, like:

let mut XY = XYBackend::new();
vg.write_xy(..., &mut XY); 

let xc: Vec<f32> = XY.x; // x-coordinates of the nodes 
let yc: Vec<f32> = XY.y; // y-coordinates of the nodes 
... // other positioning info