CMake: add WITH_BLENDER_THUMBNAILER option

Make building the thumbnail extraction executable optional,
disable on macOS as this was not linking, further, macOS doesn't use
this for thumbnail extraction so it could be left disabled.

CMakeLists.txt

@@ -156,6 +156,16 @@ get_blender_version()
 option(WITH_BLENDER "Build blender (disable to build only the blender player)" ON)
 mark_as_advanced(WITH_BLENDER)
 
+if(APPLE)
+  # Currently this causes a build error linking, disable.
+  set(WITH_BLENDER_THUMBNAILER OFF)
+elseif(WIN32)
+  # Building the thumbnail extraction DLL could be made optional.
+  set(WITH_BLENDER_THUMBNAILER ON)
+else()
+  option(WITH_BLENDER_THUMBNAILER "Build \"blender-thumbnailer\" thumbnail extraction utility" ON)
+endif()
+
 option(WITH_INTERNATIONAL "Enable I18N (International fonts and text)" ON)
 
 option(WITH_PYTHON        "Enable Embedded Python API  (only disable for development)" ON)

build_files/cmake/config/blender_lite.cmake

@@ -9,6 +9,7 @@ set(WITH_INSTALL_PORTABLE    ON  CACHE BOOL "" FORCE)
 
 set(WITH_ALEMBIC             OFF CACHE BOOL "" FORCE)
 set(WITH_AUDASPACE           OFF CACHE BOOL "" FORCE)
+set(WITH_BLENDER_THUMBNAILER OFF CACHE BOOL "" FORCE)
 set(WITH_BOOST               OFF CACHE BOOL "" FORCE)
 set(WITH_BUILDINFO           OFF CACHE BOOL "" FORCE)
 set(WITH_BULLET              OFF CACHE BOOL "" FORCE)

source/blender/CMakeLists.txt

@@ -131,7 +131,10 @@ add_subdirectory(io)
 add_subdirectory(functions)
 add_subdirectory(makesdna)
 add_subdirectory(makesrna)
-add_subdirectory(blendthumb)
+
+if(WITH_BLENDER_THUMBNAILER)
+  add_subdirectory(blendthumb)
+endif()
 
 if(WITH_COMPOSITOR)
   add_subdirectory(compositor)

source/creator/CMakeLists.txt

@@ -515,10 +515,12 @@ if(UNIX AND NOT APPLE)
       DESTINATION "."
     )
 
-    install(
-      TARGETS blender-thumbnailer
-      DESTINATION "."
-    )
+    if(WITH_BLENDER_THUMBNAILER)
+      install(
+        TARGETS blender-thumbnailer
+        DESTINATION "."
+      )
+    endif()
 
     if(EXISTS ${LIBDIR}/mesa)
       install(DIRECTORY ${LIBDIR}/mesa/lib DESTINATION ".")
@@ -558,10 +560,12 @@ if(UNIX AND NOT APPLE)
       FILES ${CMAKE_SOURCE_DIR}/release/freedesktop/icons/symbolic/apps/blender-symbolic.svg
       DESTINATION share/icons/hicolor/symbolic/apps
     )
-    install(
-      TARGETS blender-thumbnailer
-      DESTINATION bin
-    )
+    if(WITH_BLENDER_THUMBNAILER)
+      install(
+        TARGETS blender-thumbnailer
+        DESTINATION bin
+      )
+    endif()
     set(BLENDER_TEXT_FILES_DESTINATION share/doc/blender)
   endif()