[Ctk-developers] Changes to the buildsystem for external plug-in support

[Sascha Zelzer]

Hi Folks,

I would like to merge yet another couple of changes to the CTK 
buildsystem. They enable support for writing CTK plug-ins in external 
projects, which use CTK as a toolkit. The changes also improve the 
buildsystem for CTK itself. Here are the details:

Branch: https://github.com/saschazelzer/CTK/commits/buildsystem
Relevant commit: 
https://github.com/saschazelzer/CTK/commit/9a6381c9074d2a7a77967da50e2a4db237435dee

Overview of changes:

  - Setup include directories inside a function (special support for 
non-CTK plug-ins added)
  - Use the above function in the ctkMacroBuild* macros
  - Added a check if plug-in dependencies exist at all (known_targets 
variable in ctkMacroValidateBuildOptions.cmake)
  - Smalle changes to ctkMacroValidateBuildOptions.cmake to generalize 
it so it is usable outside of CTK
  - Added a function (ctkFunctionSetupExternalPlugins.cmake) for easy 
configuration of plug-ins in external projects
  - Use the EXPORT CMake command and include the exports file in 
CTKConfig.cmake

The last item in the list might be the one with the biggest overall 
influence, since it changes the way how CTK libraries are linked from 
inside external projects (i.e. Slicer).

Thanks for your feedback,

Sascha