canvas.addPaintListener(new PaintListener()
   public void paintControl(PaintEvent e)
       // Get the Graphics Context (GC) from the PaintEvent
       GC gc = e.gc;

       // Get the width of the canvas
       int canvasWidth = canvas.getSize().x;

       String text = "The Quick Brown Fox";

       // Use the method stringExtent(String) which returns a
       // and access the x variable of the Point which contains the width of the given String
       // when plotted with the current Font on the Canvas
       int textWidth = gc.stringExtent(text).x;

       // Plot centred by subtracting half the width of the string from the centre of the Canvas width
       gc.drawText(text, canvasWidth / 2 - textWidth / 2, 0);