I'm using the QwtPlotSpectrogram class to draw a spectrogram from a matrix of doubles. The matrix data is updating row-by-row and is updating at an extremely fast rate. Calling replot() works fine when my canvas is small, but when my canvas is large, replot() takes too long and can't keep up with the update rate of the canvas (i.e., plotting the updates is very jumpy and isn't smooth enought. Is there a way to selectively redraw parts of the canvas? For instance, if I have a canvas which is 1024x768 pixels, how could I redraw only the 1024 pixels in row N? I see there's a QPixmap object called paintCache in QwtPlotCanvas which seems like a good place to start looking, but I was wondering if anyone knew of an easy solution.

Thanks in advance,
MSUdom5