- Fix VERSION.
- Make plugins that depend upon cairo optional.
- Add logic so extra plugins can build without installing base components.

--- CMakeLists.txt.orig	2026-06-08 12:51:55 UTC
+++ CMakeLists.txt
@@ -20,6 +20,8 @@ include(CTest)
 set(CMAKE_CTEST_ARGUMENTS "--verbose")
 include(CTest)
 
+option (BUILD_EXTRA_PLUGINS "Build plugins with optional dependencies" ON)
+
 option (WITHOUT_OPENCV "Disable plugins dependent upon OpenCV" OFF)
 option (WITHOUT_FACERECOGNITION "Disable facedetect plugin to avoid protobuf conflicts" OFF)
 
@@ -54,20 +56,28 @@ INCLUDE( cmake/modules/TargetDistclean.cmake OPTIONAL)
 # --- custom targets: ---
 INCLUDE( cmake/modules/TargetDistclean.cmake OPTIONAL)
 
-install(DIRECTORY ${CMAKE_SOURCE_DIR}/include/ DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
+if (NOT BUILD_EXTRA_PLUGINS)
+  install(DIRECTORY ${CMAKE_SOURCE_DIR}/include/ DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
 
 # For code documentation run: doxygen doc/Doxyfile
 # add_subdirectory (doc)
 
-add_subdirectory (src)
+  add_subdirectory (src)
+else ()
+  add_subdirectory (src/filter)
+  add_subdirectory (src/mixer2)
+endif ()
+
 if (BUILD_TESTING)
   add_subdirectory (test)
 endif ()
 
-# Generate frei0r.pc and install it.
-set (prefix "${CMAKE_INSTALL_PREFIX}")
-set (exec_prefix "${CMAKE_INSTALL_PREFIX}")
-set (libdir "${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}")
-set (includedir "${CMAKE_INSTALL_PREFIX}/include")
-configure_file ("frei0r.pc.in" "frei0r.pc" @ONLY)
-install (FILES "${CMAKE_CURRENT_BINARY_DIR}/frei0r.pc" DESTINATION "${CMAKE_INSTALL_LIBDIR}/pkgconfig")
+if (NOT BUILD_EXTRA_PLUGINS)
+  # Generate frei0r.pc and install it.
+  set (prefix "${CMAKE_INSTALL_PREFIX}")
+  set (exec_prefix "${CMAKE_INSTALL_PREFIX}")
+  set (libdir "${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}")
+  set (includedir "${CMAKE_INSTALL_PREFIX}/include")
+  configure_file ("frei0r.pc.in" "frei0r.pc" @ONLY)
+  install (FILES "${CMAKE_CURRENT_BINARY_DIR}/frei0r.pc" DESTINATION "${CMAKE_INSTALL_LIBDIR}/pkgconfig")
+endif()