1 files changed, 73 insertions, 0 deletions
diff --git a/src/nativewindow/native/win32/WindowsSHC.c b/src/nativewindow/native/win32/WindowsSHC.c
new file mode 100644
index 000000000..45cefb126
--- /dev/null
+++ b/src/nativewindow/native/win32/WindowsSHC.c
@@ -0,0 +1,73 @@
+
+#include <windows.h>
+#include "WindowsSHC.h"
+
+#include <stdlib.h>
+#include <stdio.h>
+
+// #define VERBOSE_ON 1
+
+#ifdef VERBOSE_ON
+    #define DBG_PRINT(args...) fprintf(stderr, args);
+#else
+    #define DBG_PRINT(args...)
+#endif
+
+/* GetProcAddress doesn't exist in A/W variants under desktop Windows */
+#ifndef UNDER_CE
+#define GetProcAddressA GetProcAddress
+#endif
+
+typedef HRESULT(WINAPI *GetDpiForMonitorPROCADDR)(HMONITOR, int, UINT*, UINT*);
+#ifndef MDT_EFFECTIVE_DPI
+    #define MDT_EFFECTIVE_DPI 0
+#endif
+// See also SetProcessDpiAwareness(..) and SetThreadDpiAwarenessContext(..)
+
+#define INIT_CALLED_MASK          1 << 0
+#define INIT_HAS_SHC_EXT_MASK     1 << 1
+
+#define HAS_INIT(a)        ( 0 != ( INIT_CALLED_MASK & (a)  ) )
+#define HAS_SHC_EXT(a)     ( 0 != ( INIT_HAS_SHC_EXT_MASK & (a)  ) )
+
+static int _init = 0; // INIT_ bits, see above
+static GetDpiForMonitorPROCADDR _GetDpiForMonitor = NULL;
+
+static int initWindowsSHC() {
+    if( !HAS_INIT(_init) ) {
+        _init |= INIT_CALLED_MASK;
+        HANDLE hShcAPI = LoadLibrary(TEXT("shcore.dll"));
+        if (hShcAPI) {
+            _GetDpiForMonitor = (GetDpiForMonitorPROCADDR) GetProcAddressA (hShcAPI, "GetDpiForMonitor");
+            if(NULL != _GetDpiForMonitor ) {
+                _init |= INIT_HAS_SHC_EXT_MASK;
+            }
+        }
+        // FreeLibrary (hShcAPI);
+        DBG_PRINT("DWM - initWindowsSHC: hasSHC %d\n", HAS_SHC_EXT(_init));
+    }
+    return _init;
+}
+
+BOOL ShcIsExtensionAvailable() {
+    return HAS_SHC_EXT( initWindowsSHC() ) ? TRUE : FALSE;
+}
+
+BOOL ShcGetMonitorPixelScale1(HMONITOR hmon, float *psXY) {
+    psXY[0] = 0;
+    psXY[1] = 0;
+    if( !ShcIsExtensionAvailable() ) {
+        return FALSE;
+    }
+    if( NULL == hmon ) {
+        return FALSE;
+    }
+    UINT dpiX=0, dpiY=0;
+    if( S_OK != _GetDpiForMonitor(hmon, MDT_EFFECTIVE_DPI, &dpiX, &dpiY) ) {
+        return FALSE;
+    }
+    psXY[0] = (float)(dpiX) / 96.0f;
+    psXY[1] = (float)(dpiY) / 96.0f;
+    return TRUE;
+}
+