QwtPlotCurve draw it's full contents without using current zoom information

[Dmitri]

I'm check Qwt 6.0.1.

I have data from ADC with 200 Hz. Next i'm load to QwtPlot data with one hour from file. That's 3600*200 = 720 000 points. Second i'm install QwtPlotZoomer for zooming and draging plot (In future i'm want to use scrollbar navigation). The problem that QwtPlotCurve draw it's full contents without gettings information from current zoom is VERY SLOW.

I'm find this code that always calling before the curve is draw:

qwt_plot_seriesitem.cpp:

void QwtPlotAbstractSeriesItem::draw( QPainter *painter,
        const QwtScaleMap &xMap, const QwtScaleMap &yMap,
        const QRectF &canvasRect ) const
{
    drawSeries( painter, xMap, yMap, canvasRect, 0, -1 );
}

void QwtPlotAbstractSeriesItem::draw( QPainter *painter,
        const QwtScaleMap &xMap, const QwtScaleMap &yMap,
        const QRectF &canvasRect ) const
{
    drawSeries( painter, xMap, yMap, canvasRect, 0, -1 );
}

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We can see that curve always draw it's full contents (from = 0, to = -1 (size of data)).

Is it possible to workaround this behaviour?