Make FreeType library tied to the module

This ensures that a new one will be created for each sub-interpreter, or
if the module is reloaded.

Author: QuLogic

src/ft2font.cpp

@@ -41,8 +41,6 @@
       you have disabled hints).
  */
 
-FT_Library _ft2Library;
-
 FT2Image::FT2Image(unsigned long width, unsigned long height)
     : m_buffer((unsigned char *)calloc(width * height, 1)), m_width(width), m_height(height)
 {
@@ -207,7 +205,7 @@ FT2Font::get_path(std::vector<double> &vertices, std::vector<unsigned char> &cod
     codes.push_back(CLOSEPOLY);
 }
 
-FT2Font::FT2Font(FT_Open_Args &open_args,
+FT2Font::FT2Font(FT_Library ft2Library, FT_Open_Args &open_args,
                  long hinting_factor_,
                  std::vector<FT2Font *> &fallback_list,
                  FT2Font::WarnFunc warn, bool warn_if_used)
@@ -217,7 +215,7 @@ FT2Font::FT2Font(FT_Open_Args &open_args,
       kerning_factor(0)
 {
     clear();
-    FT_CHECK(FT_Open_Face, _ft2Library, &open_args, 0, &face);
+    FT_CHECK(FT_Open_Face, ft2Library, &open_args, 0, &face);
     if (open_args.stream != nullptr) {
         face->face_flags |= FT_FACE_FLAG_EXTERNAL_STREAM;
     }

src/ft2font.h

@@ -92,14 +92,12 @@ class FT2Image
     FT2Image &operator=(const FT2Image &);
 };
 
-extern FT_Library _ft2Library;
-
 class FT2Font
 {
     typedef void (*WarnFunc)(FT_ULong charcode, std::set<FT_String*> family_names);
 
   public:
-    FT2Font(FT_Open_Args &open_args, long hinting_factor,
+    FT2Font(FT_Library ft2Library, FT_Open_Args &open_args, long hinting_factor,
             std::vector<FT2Font *> &fallback_list,
             WarnFunc warn, bool warn_if_used);
     virtual ~FT2Font();

src/ft2font_wrapper.cpp

@@ -379,7 +379,7 @@ const char *PyFT2Font_init__doc__ = R"""(
 )""";
 
 static PyFT2Font *
-PyFT2Font_init(py::object filename, long hinting_factor = 8,
+PyFT2Font_init(FT_Library ft2Library, py::object filename, long hinting_factor = 8,
                std::optional<std::vector<PyFT2Font *>> fallback_list = std::nullopt,
                int kerning_factor = 0, bool warn_if_used = false)
 {
@@ -430,8 +430,8 @@ PyFT2Font_init(py::object filename, long hinting_factor = 8,
         self->stream.close = nullptr;
     }
 
-    self->x = new FT2Font(open_args, hinting_factor, fallback_fonts, ft_glyph_warn,
-                          warn_if_used);
+    self->x = new FT2Font(ft2Library, open_args, hinting_factor, fallback_fonts,
+                          ft_glyph_warn, warn_if_used);
 
     self->x->set_kerning_factor(kerning_factor);
 
@@ -1477,12 +1477,14 @@ ft2font__getattr__(std::string name) {
 
 PYBIND11_MODULE(ft2font, m, py::mod_gil_not_used())
 {
-    if (FT_Init_FreeType(&_ft2Library)) {  // initialize library
+    FT_Library ft2Library = nullptr;
+
+    if (FT_Init_FreeType(&ft2Library)) {  // initialize library
         throw std::runtime_error("Could not initialize the freetype2 library");
     }
     FT_Int major, minor, patch;
     char version_string[64];
-    FT_Library_Version(_ft2Library, &major, &minor, &patch);
+    FT_Library_Version(ft2Library, &major, &minor, &patch);
     snprintf(version_string, sizeof(version_string), "%d.%d.%d", major, minor, patch);
 
     py::native_enum<FT_Kerning_Mode>(m, "Kerning", "enum.Enum", Kerning__doc__)
@@ -1597,7 +1599,14 @@ PYBIND11_MODULE(ft2font, m, py::mod_gil_not_used())
 
     py::classh<PyFT2Font>(m, "FT2Font", py::is_final(), py::buffer_protocol(),
                           PyFT2Font__doc__)
-        .def(py::init(&PyFT2Font_init),
+        .def(py::init(
+            [ft2Library](py::object filename, long hinting_factor = 8,
+                std::optional<std::vector<PyFT2Font *>> fallback_list = std::nullopt,
+                int kerning_factor = 0, bool warn_if_used = false) -> PyFT2Font *
+            {
+                return PyFT2Font_init(ft2Library, filename, hinting_factor,
+                                      fallback_list, kerning_factor, warn_if_used);
+            }),
              "filename"_a, "hinting_factor"_a=8, py::kw_only(),
              "_fallback_list"_a=py::none(), "_kerning_factor"_a=0,
              "_warn_if_used"_a=false,
@@ -1754,6 +1763,18 @@ PYBIND11_MODULE(ft2font, m, py::mod_gil_not_used())
             return self.x->get_image().request();
         });
 
+    // Ensure FreeType library is closed after all instances of FT2Font are gone by
+    // tying a weak ref to the class itself.
+    (void)py::weakref(
+        m.attr("FT2Font"),
+        py::cpp_function(
+            [ft2Library](py::handle weakref) {
+                FT_Done_FreeType(ft2Library);
+                weakref.dec_ref();
+            }
+        )
+    ).release();
+
     m.attr("__freetype_version__") = version_string;
     m.attr("__freetype_build_type__") = FREETYPE_BUILD_TYPE;
     m.def("__getattr__", ft2font__getattr__);