[Discuss-gnuradio] How to compile the example alone？

I discover a example about how to compile the qtgui in c++. The example's path is "gnuradio/gr-qtgui/examples/c++/display_qt.cc"(The website is https://github.com/gnuradio/gnuradio/tree/master/gr-qtgui/examples/c%2B%2B). But I don't know how to compile it singlely. I try to rewrite the CMakeLists.txt. However, I fail...

So if anyone know how to compile the display_qt.cc or how to rewrite the CMakeLists.txt, please teach me. Thanks very much!