How to manually set the zoom on a Jung visualisation?

Question

I have a jung tree displayed in a JPanel. The constructor of my tree looks like this:

  Forest graph = new DelegateForest

        

Answer 1

ScalingControl is not good method if you use Mouse Transformer.

Try to:

// for zoom:
vv.getRenderContext().getMultiLayerTransformer().getTransformer(Layer.LAYOUT).setScale(scale_x1, scale_y1, vv.getCenter());
// for out:
vv.getRenderContext().getMultiLayerTransformer().getTransformer(Layer.VIEW).setScale(scale_x2, scale_y2, vv.getCenter());

Answer 2

ScalingControl scaler = new CrossoverScalingControl();

public void zoomIn() {
    setZoom(1);
}

public void zoomOut() {
    setZoom(-1);
}

private void setZoom(int amount) {
    scaler.scale(vv, amount > 0 ? 1.1f : 1 / 1.1f, vv.getCenter());
}

To fits the graph on the window, you can calculate the diference between the graph size and the panel size, and call the setZoom() method passing the factor of diference.