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

--- CMakeLists.txt.orig	2025-09-03 14:34:34 UTC
+++ CMakeLists.txt
@@ -3,16 +3,21 @@ project (frei0r)
 list (APPEND CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake/modules)
 
 project (frei0r)
-set (VERSION 1.8)
+set (VERSION 2.4.0)
 
 include(GNUInstallDirs)
 
+option (BUILD_EXTRA_PLUGINS "Build plugins with optional dependencies" ON)
+
 option (WITHOUT_OPENCV "Disable plugins dependent upon OpenCV" OFF)
 if (NOT WITHOUT_OPENCV)
   find_package (OpenCV)
 endif ()
 
-find_package (Cairo)
+option (WITHOUT_CAIRO "Disable plugins dependent upon cairo" OFF)
+if (NOT WITHOUT_CAIRO)
+  find_package (Cairo)
+endif ()
 
 include(FindPkgConfig)
 option (WITHOUT_GAVL "Disable plugins dependent upon gavl" OFF)
@@ -35,17 +40,24 @@ 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 ()
 
 # 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 "${CMAKE_INSTALL_LIBDIR}/pkgconfig")
+if (NOT BUILD_EXTRA_PLUGINS)
+  configure_file ("frei0r.pc.in" "frei0r.pc" @ONLY)
+  install (FILES "${CMAKE_CURRENT_BINARY_DIR}/frei0r.pc" DESTINATION "libdata/pkgconfig")
+endif ()