Resize Processing canvas in JavaFX window

[Lexyth]

Try taking a look at this one :

Resizable window with constrained proportions

When I need the canvas to be resizable I use surface.setResizable(true);. However, I need to keep the width and height equal and can’t seem to find a way to apply constraints to do so. I initially tried to manually set the size to keep the dimensions proportional, but that led to unpleasant flickering when I resized the window. Any ideas on the best way to implement this are welcome. Thanks!