title: Manipulating a QGradient to follow a path
body: <p>I am using Qt to draw something that looks like a pipe which can curve and arc using a QPainterPath.  I use a QLinearGradient to fill the pipe in order to give it a three dimensional look.  What I can't figure out is how to curve/arc the pipe and have the gradient <em>follow</em> those same curves so that the 3D effect remains.  Any thoughts?</p>
  
  <p>In other words, the color stops on the QGradient need to rotate along with the curves in the path.</p>