How to clear QwtPlot curves before replotting?

Question

In the earlier versions of Qwt we add QwtPlot::clear() but now, I can't find it.

Any ideas? I have a real time plot, so when replotting, the info before xmin is not really important and with time it crashes as the replot is replotting all the information before xmin.

bruno · Accepted Answer · 2013-03-13T14:06:31.337

5

The method Qwtplot::clear() has been deprecated. Use QwtPlotDict::detachItems instead.

void QwtPlotDict::detachItems(int rtti = QwtPlotItem::Rtti_PlotItem, 
                              bool autoDelete = true 
                             )

Parameters:

rtti: In case of QwtPlotItem::Rtti_PlotItem detach all items otherwise only those items of the type rtti. autoDelete: If true, delete all detached items

edited Mar 13 '13 at 14:06

answered Mar 13 '13 at 13:46

bruno

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well, I used this ` for (int i = 0; i < 8; i++) { plot_all[i]->detachItems(QwtPlotItem::Rtti_PlotItem, true); plot[i]->detachItems(QwtPlotItem::Rtti_PlotItem, true); }`and it didn's detach the `QwtCurves` – SamuelNLP Mar 13 '13 at 14:16
1

what happens when you call the function with no arguments? Like plot_all[i]->detachItems(); – bruno Mar 13 '13 at 14:24

score 2 · Answer 2 · answered Nov 06 '13 at 06:15

one of the way to clear plot is to set your data points to empty: for example: (m_vctTime,m_vctValue -vector) (curve=new QwtPlotCurve()) (plot=new QwtPlot(parent))

m_vctTime.clear();
m_vctValue.clear();
curve->setSamples(m_vctTime,m_vctValue);
plot->replot();

that clears your plot

How to clear QwtPlot curves before replotting?

2 Answers2