Replot large wav file data

[Sachtech]

Hi,

I am plotting a .wav file using qwt5.2 svn. The file is around 1 minute long. The number of data points are around 10 lakh points. I am trying to move a marker around 100 ms (replot every 100 ms) to synchronize with the audio. Somehow the marker is moving very slowly.

Any suggestions on how I should call replot and setrawdata.

Sample code

tick(qint64 time)
{
indicator_x1[0] = ((time / (double)1000))* Audio->getSampleRate();
indicator_x1[1] = indicator_x1[0];
indicator_x2[0] = -1;
indicator_x2[1] = +1;
curve->setRawData(indicator_x1, indicator_x2,2); // This statement seems to be the problem.
qwtPlot->replot();

}


regards
sachin.

[Uwe]

I am trying to move a marker around 100 ms (replot every 100 ms) to synchronize with the audio. Somehow the marker is moving very slowly.

When the marker is the only thing, that is moving you should cache the scene below the marker in a pixmap. If you implement the marker with a QwtPlotPicker, you don't have to implement the cache yourself, otherwise overload QwtPlot::drawItems().

Uwe