CMake: generate SkUserConfig.h

cmake/CMakeLists.txt

Index: cmake/CMakeLists.txt
diff --git a/cmake/CMakeLists.txt b/cmake/CMakeLists.txt
index cd71de74b7b9843d81a66ccc8aabe5b7002274eb..f87b5f836b276868974cf1060ee525f9ebe8ccc6 100644
--- a/cmake/CMakeLists.txt
+++ b/cmake/CMakeLists.txt
@@ -8,6 +8,17 @@ if (NOT CMAKE_BUILD_TYPE)
     set (CMAKE_BUILD_TYPE Release)
 endif ()
 
+set (userconfig_directory ${CMAKE_BINARY_DIR}/include)
+set (userconfig_path ${userconfig_directory}/SkUserConfig.h)
+file(WRITE ${userconfig_path} "// SkUserConfig generated by CMake.\n")
+if (CMAKE_BUILD_TYPE STREQUAL Release)
+  file(APPEND ${userconfig_path} "#define SK_RELEASE\n")
+  file(APPEND ${userconfig_path} "#undef SK_DEBUG\n")
+else ()
+  file(APPEND ${userconfig_path} "#define SK_DEBUG\n")
+  file(APPEND ${userconfig_path} "#undef SK_RELEASE\n")
+endif ()
+
 # To first approximation, the Skia library comprises all .cpp files under src/.
 file (GLOB_RECURSE srcs ../src/*.cpp)
 
@@ -26,6 +37,9 @@ endfunction()
 find_include_dirs(private_includes ../src/*.h ../include/private/*.h)
 find_include_dirs(public_includes ../include/*.h)
 list (REMOVE_ITEM public_includes ${private_includes})  # Easiest way to exclude private.
+file (GLOB default_include_config "../include/config")
+list (REMOVE_ITEM public_includes ${default_include_config})
+list (APPEND public_includes ${userconfig_directory})
 
 # These guys are third_party but provided by a Skia checkout.
 list (APPEND srcs             ../third_party/etc1/etc1.cpp ../third_party/ktx/ktx.cpp)
@@ -201,6 +215,7 @@ if (OSMESA_LIBRARIES AND OSMESA_INCLUDE_DIRS)
     list (APPEND libs             ${OSMESA_LIBRARIES})
     list (APPEND private_includes ${OSMESA_INCLUDE_DIRS})
     list (APPEND public_defines   "-DSK_MESA=1")
+    file (APPEND ${userconfig_path} "#define SK_MESA 1\n")
 else()
     remove_srcs(../src/gpu/gl/mesa/*)
 endif()