It is a good idea to store the sources which was generated in the last step
and compare it with new generated sources.
Then you see better and obvious the difference what's happen if the graphic is changed.
The destination dir for the sources to generate is usual 

.../build/COMPONENT/cpp/genSrc/*

This currently geneated sources can be used as input for the compiler.
Then subsequently the make process and also execution can be started after change the graphic.
The other possibility is: Use the src/COMPONENT/cpp/genSrc here for the compilation.
Then the sources are also available if build is cleanded (may be a scratch RAM disk) without new generation from graphic.
The sources should then always synchronize from build/... after build.

Both approaches are sensible.
