this is fork from qwt lib
add the cmake ,can build with qt5 and qt6
Perhaps some improvements will also be submitted to this hub
Qwt is an extension to the libraries of the Qt Project.
The Qwt library contains widgets and components which are
primarily useful for technical and scientifical purposes.
It includes a 2-D plotting widget, different kinds of sliders,
and much more.
Qwt is hosted at http://qwt.sf.net
Qwt Widget Library
Copyright (C) 1997 Josef Wilgen
Copyright (C) 2002 Uwe Rathmann
Qwt is published under the Qwt License, Version 1.0.
You should have received a copy of this licence in the file
COPYING.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.