cmake: build libs+examples when configured from the DPF dir

CMakeLists.txt

@@ -2,7 +2,15 @@ cmake_minimum_required(VERSION 3.7)
 
 project(DPF)
 
-option(DPF_EXAMPLES "Build the examples" OFF)
+# check if we are building from this project, or are imported by another
+if(PROJECT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
+  set(DPF_BUILD_FROM_HERE TRUE)
+else()
+  set(DPF_BUILD_FROM_HERE FALSE)
+endif()
+
+option(DPF_LIBRARIES "Build the libraries" "${DPF_BUILD_FROM_HERE}")
+option(DPF_EXAMPLES "Build the examples" "${DPF_BUILD_FROM_HERE}")
 
 set(DPF_ROOT_DIR "${PROJECT_SOURCE_DIR}" CACHE INTERNAL
   "Root directory of the DISTRHO Plugin Framework.")
@@ -10,6 +18,11 @@ set(DPF_ROOT_DIR "${PROJECT_SOURCE_DIR}" CACHE INTERNAL
 list(APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake")
 include(DPF-plugin)
 
+if(DPF_LIBRARIES)
+  dpf__add_dgl_cairo()
+  dpf__add_dgl_opengl()
+endif()
+
 if(DPF_EXAMPLES)
   add_subdirectory("examples/CairoUI")
   #add_subdirectory("examples/ExternalUI")

cmake/DPF-plugin.cmake

@@ -280,7 +280,7 @@ function(dpf__add_dgl_cairo)
   find_package(PkgConfig)
   pkg_check_modules(CAIRO "cairo" REQUIRED)
 
-  dpf__add_static_library(dgl-cairo EXCLUDE_FROM_ALL
+  dpf__add_static_library(dgl-cairo STATIC
     "${DPF_ROOT_DIR}/dgl/src/Application.cpp"
     "${DPF_ROOT_DIR}/dgl/src/Color.cpp"
     "${DPF_ROOT_DIR}/dgl/src/Geometry.cpp"
@@ -326,7 +326,7 @@ function(dpf__add_dgl_opengl)
 
   find_package(OpenGL REQUIRED)
 
-  dpf__add_static_library(dgl-opengl EXCLUDE_FROM_ALL
+  dpf__add_static_library(dgl-opengl STATIC
     "${DPF_ROOT_DIR}/dgl/src/Application.cpp"
     "${DPF_ROOT_DIR}/dgl/src/Color.cpp"
     "${DPF_ROOT_DIR}/dgl/src/Geometry.cpp"