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c++qtqwt

QwtPlotCurve doesn't show up on graph

I'm currently working on a project in which I load a huge number of data points on a graph (something like 50,000, so I can zoom in as much as I want).

I wanted to test how the commands worked, so I thought I'd try out the code with 10 pieces of data, but unfortunately my curve refuses to show up on my graph.

QwtPlot *leftGraph;
leftGraph = new QwtPlot;
leftGraph->setCanvasBackground(Qt::white);

leftGraph->setMaximumHeight(200);

leftGraph->setAxisScale(0, 0.0, 20.0, 2.0);
leftGraph->setAxisScale(2, 0.0, 20.0, 2.0);

and

QwtPlotCurve *curve = new QwtPlotCurve();
curve->setStyle(QwtPlotCurve::Lines);
curve->setCurveAttribute(QwtPlotCurve::Fitted, true);


const double x[] = {0, 1, 2, 4, 5, 8, 10, 13, 14, 19};
const double y[] = {17, 16.5, 8, 3, 5, 7.5, 9, 10, 12, 14};

curve->setSamples(x, y, 10);
curve->attach(leftGraph);

Any ideas? Many thanks.

Solution

  • Try calling leftGraph->replot() to make the curve appear.