Merge pull request #26 from nulano/imagegrab-dynamic-link

Fix GetWindowDpiAwarenessContext NULL check

Author: radarhere

src/display.c

@@ -329,7 +329,7 @@ PyImaging_GrabScreenWin32(PyObject *self, PyObject *args) {
     HWND wnd;
     DWORD rop;
     PyObject *buffer;
-    HANDLE dpiAwareness;
+    HANDLE dpiAwareness = NULL;
     HMODULE user32;
     Func_GetWindowDpiAwarenessContext GetWindowDpiAwarenessContext_function;
     Func_SetThreadDpiAwarenessContext SetThreadDpiAwarenessContext_function;
@@ -360,22 +360,15 @@ PyImaging_GrabScreenWin32(PyObject *self, PyObject *args) {
     SetThreadDpiAwarenessContext_function = (Func_SetThreadDpiAwarenessContext
     )GetProcAddress(user32, "SetThreadDpiAwarenessContext");
     if (SetThreadDpiAwarenessContext_function != NULL) {
-        if (screens == -1) {
-            GetWindowDpiAwarenessContext_function = (Func_GetWindowDpiAwarenessContext
-            )GetProcAddress(user32, "GetWindowDpiAwarenessContext");
-            DPI_AWARENESS_CONTEXT dpiAwarenessContext =
-                GetWindowDpiAwarenessContext_function(wnd);
-            if (GetWindowDpiAwarenessContext_function != NULL &&
-                dpiAwarenessContext != NULL) {
-                dpiAwareness =
-                    SetThreadDpiAwarenessContext_function(dpiAwarenessContext);
-            } else {
-                dpiAwareness = SetThreadDpiAwarenessContext_function((HANDLE)-3);
-            }
-        } else {
-            // DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE = ((DPI_CONTEXT_HANDLE)-3)
-            dpiAwareness = SetThreadDpiAwarenessContext_function((HANDLE)-3);
+        GetWindowDpiAwarenessContext_function = (Func_GetWindowDpiAwarenessContext
+        )GetProcAddress(user32, "GetWindowDpiAwarenessContext");
+        if (screens == -1 && GetWindowDpiAwarenessContext_function != NULL) {
+            dpiAwareness = GetWindowDpiAwarenessContext_function(wnd);
         }
+        // DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE = ((DPI_CONTEXT_HANDLE)-3)
+        dpiAwareness = SetThreadDpiAwarenessContext_function(
+            dpiAwareness == NULL ? (HANDLE)-3 : dpiAwareness
+        );
     }
 
     if (screens == 1) {