JavaFX - Resize Canvas when screen is resized

To make a JavaFx canvas resizable all that needs to be done is override the min/pref/max methods. Make it resizable and implement the resize method.

With this method no width/height listeners are necessary to trigger a redraw. It is also no longer necessary to bind the size of the width and height to the container.

public class ResizableCanvas extends Canvas {

@Override
public double minHeight(double width)
{
    return 64;
}

@Override
public double maxHeight(double width)
{
    return 1000;
}

@Override
public double prefHeight(double width)
{
    return minHeight(width);
}

@Override
public double minWidth(double height)
{
    return 0;
}

@Override
public double maxWidth(double height)
{
    return 10000;
}

@Override
public boolean isResizable()
{
    return true;
}

@Override
public void resize(double width, double height)
{
    super.setWidth(width);
    super.setHeight(height);
    paint();
}

Note that the resize method cannot simply call Node.resize(width,height), because the standard implementation is effectivele empty.

As James_D pointed out, you need to redraw the content of your canvas when resizing. This can be done by adding a listener to your canvas' width and height property as follows:

InvalidationListener listener = new InvalidationListener(){
    @Override
    public void invalidated(Observable o) {
        redraw();       
    }           
});
canvas.widthProperty().addListener(listener);
canvas.heightProperty().addListener(listener);

or in Java 8 using functional interfaces:

canvas.widthProperty().addListener(observable -> redraw());
canvas.heightProperty().addListener(observable -> redraw());

where redraw() is your own method which would look like this for your example (drawing a black rectangle:

private void redraw() {
    g.setFill(Color.BLACK);
    g.fillRect(0, 0, canvas.getWidth(), canvas.getHeight());
}