I need to show it when the mouse is being dragged above the Qwt plot, even without pressing any buttons. I know, that it's simple, but how?
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I need to show it when the mouse is being dragged above the Qwt plot, even without pressing any buttons. I know, that it's simple, but how?
picker->setTrackerMode(QwtPicker::AlwaysOn);
Rounding algo should be set by using QwtPicker::trackerText function.
Showing value of f(x) - I think this should be your function - first it should calculate x value of picker, then it should iterate through your curve and find this exact x value, or interpolate y value if picker's x value lies between two points of your curve.
This value should be given to picker to show, or put some label, or write this value in statusBar, it's up to you.