plugin.pro Example File

 TEMPLATE    = lib
 CONFIG     += plugin
 HEADERS     = simplestyle.h \
               simplestyleplugin.h
 SOURCES     = simplestyle.cpp \
               simplestyleplugin.cpp
 OTHER_FILES += simplestyle.json
 TARGET      = simplestyleplugin
 win32 {
     CONFIG(debug, release|debug):DESTDIR = ../debug/styles/
     CONFIG(release, release|debug):DESTDIR = ../release/styles/
 } else {
     DESTDIR = ../styles/
 }

 # install
 target.path = $$[QT_INSTALL_EXAMPLES]/qtbase/tools/styleplugin/styles
 sources.files = $$SOURCES $$HEADERS $$RESOURCES $$FORMS plugin.pro
 sources.path = $$[QT_INSTALL_EXAMPLES]/qtbase/tools/styleplugin/plugin
 INSTALLS += target sources

 QT += widgets