Qwt realtime plotting using QwtPlotDirectPainter

[cheuwleeyeo]

Hi,

I am a newbie to Qt/Qwt; but find it very useful; I am having similar question as Jean-Luc; I have been studying Qwt examples: Oscilloscope, Refreshtest, and Curvedemo2.

Oscilloscope does a 'replot" so the plot is restarted at the beginning of the plot window, Refreshtest does a "scroll" to the data; I would like to do a "erase bar" to the wave; so very similar to Oscilloscope but does NOT clear the plot window; I can stop the refresh by not doing "replot" after the interval; but I can't seem to create the "simple" erase bar; ie. deleting the previous plot(eg. 5 points in the future) and replacing them with the new points(as currently done in the examples); I am thinking of doing the "brute force method" of using similar brush as background color; but thought, there maybe a better solution or even a simpler solution.

Appreciate any suggestion to do this.

Thanks.

Lee

[Uwe]

In earlier Qt releases ( Qt 3 ) it was possible to erase something by drawing in XOR mode, but this feature is lost since Qt 4.0. So the answer is simple, you can't erase something from a widget ( by Qt design ).

Uwe