Getting click coordinates from plugin

Hello everybody. I am a student and for a project I have to write a plugin on LibreCAD for positionning points in terms of others. I am working on the sample.h and sample.cpp.
I have adapted the form so that I can place and draw a point by three distances to three point already drawn.
Now I absolutely need to compute a method on this plugin that lets the user to click on the draw space and place a point where he clicked.
How can I do that ? How can I get the (x,y) click coordinates of the click so that I could create a QPointF(x,y) and call the AddPoint method of the document_interface doc object ?

I have to find a solution quick so if you have any clue to solve this problem, that would be very nice !

Thanks a lot for your help.

Continue with align.h and align.cpp in plugins folder.

QPointF point;
bool yes = doc->getPoint(&point, QString("first base point:"));
if (!yes)
    return; //cancelled, the user do no select any point

More info (outdated):

http://wiki.librecad.org/index.php/LibreCAD_Plugin_Development
http://wiki.librecad.org/index.php/Plug_Entity_class
http://wiki.librecad.org/index.php/Document_Interface_class

More info (NO outdated):

plugins/document_interface.h (fully documented)