Properly handle turning the GUI off

tools/python/CMakeLists.txt

@@ -9,7 +9,7 @@ CMAKE_MINIMUM_REQUIRED(VERSION 2.8.4)
 include(../../dlib/add_python_module)
 
 # Tell cmake to compile all these cpp files into a dlib python module.
-add_python_module(dlib 
+set(python_srcs
    src/dlib.cpp
    src/matrix.cpp
    src/vector.cpp
@@ -24,8 +24,14 @@ add_python_module(dlib
    src/image.cpp
    src/object_detection.cpp
    src/shape_predictor.cpp
-   src/gui.cpp
-   )
+)
+
+# Only add the GUI module if requested
+if(NOT ${DLIB_NO_GUI_SUPPORT})
+   list(APPEND python_srcs src/gui.cpp)
+endif(NOT ${DLIB_NO_GUI_SUPPORT})
+
+add_python_module(dlib ${python_srcs})
 
 # When you run "make install" we will copy the compiled dlib.so (or dlib.pyd) 
 # library file to the python_examples folder.

tools/python/src/dlib.cpp

@@ -16,7 +16,10 @@ void bind_svm_struct();
 void bind_image_classes();
 void bind_object_detection();
 void bind_shape_predictors();
+
+#ifndef DLIB_NO_GUI_SUPPORT
 void bind_gui();
+#endif
 
 BOOST_PYTHON_MODULE(dlib)
 {
@@ -37,6 +40,8 @@ BOOST_PYTHON_MODULE(dlib)
     bind_image_classes();
     bind_object_detection();
     bind_shape_predictors();
+#ifndef DLIB_NO_GUI_SUPPORT
     bind_gui();
+#endif
 }