How to show the value of a point under the mouse?

**YaK** · 27th February 2009, 06:38

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?

**Uwe** · 27th February 2009, 07:07

picker->setTrackerMode(QwtPicker::AlwaysOn);

**YaK** · 27th February 2009, 08:46

Originally Posted by Uwe

picker->setTrackerMode(QwtPicker::AlwaysOn);

Thank you, comrade. Yet a few more questions: can i show some rounded value with less digits into the frac. part and can i show the value of the CURVE f(x) under the same X value, that is shown on the plot?

**KosyakOFF** · 27th February 2009, 10:00

Originally Posted by YaK

Thank you, comrade. Yet a few more questions: can i show some rounded value with less digits into the frac. part and can i show the value of the CURVE f(x) under the same X value, that is shown on the plot?

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.