[gui] [ipython] Add GUI.__del__ to close on variable dereference (#1869)

* better pybuf_enabled detection

* add GUI.__del__ to close on variable dereference

* fix win32 not destroying window

* [skip ci] Update python/taichi/lang/shell.py

* nit

* [skip ci] Update python/taichi/misc/gui.py

python/taichi/lang/shell.py

@@ -15,7 +15,8 @@
 _env_enable_pybuf = os.environ.get('TI_ENABLE_PYBUF', '1')
 if not _env_enable_pybuf or int(_env_enable_pybuf):
     # When using in Jupyter / IDLE, the sys.stdout will be their wrapped ones.
-    pybuf_enabled = type(sys.stdout).__name__ != 'TextIOWrapper'
+    # While sys.__stdout__ should always be the raw console stdout.
+    pybuf_enabled = sys.stdout is not sys.__stdout__
 
 from .core import taichi_lang_core
 taichi_lang_core.toggle_python_print_buffer(pybuf_enabled)

python/taichi/misc/gui.py

@@ -59,6 +59,9 @@ def __enter__(self):
     def __exit__(self, type, val, tb):
         self.close()
 
+    def __del__(self):
+        self.close()
+
     def close(self):
         self.core = None  # dereference to call GUI::~GUI()
 
@@ -342,7 +345,8 @@ def text(self, content, pos, font_size=15, color=0xFFFFFF):
         color = ti.core_vec(r, g, b, 1)
         self.canvas.text(content, pos, font_size, color)
 
-    def _make_field_base(gui, w, h, bound):
+    @staticmethod
+    def _make_field_base(w, h, bound):
         x = np.linspace(bound / w, 1 - bound / w, w)
         y = np.linspace(bound / h, 1 - bound / h, h)
         base = np.array(np.meshgrid(x, y))

taichi/gui/win32.cpp

@@ -223,6 +223,7 @@ GUI::~GUI() {
   if (show_gui) {
     std::free(data);
     DeleteDC(src);
+    DestroyWindow(hwnd);
     gui_from_hwnd.erase(hwnd);
   }
 }