3 files changed, 69 insertions, 0 deletions
diff --git a/indra/llwindow/llwindow.h b/indra/llwindow/llwindow.h
index 0a30f4c807..a05ba8cbba 100644
--- a/indra/llwindow/llwindow.h
+++ b/indra/llwindow/llwindow.h
@@ -166,6 +166,8 @@ public:
 	// Provide native key event data
 	virtual LLSD getNativeKeyData() { return LLSD::emptyMap(); }
 
+	// Get system UI size based on DPI (for 96 DPI UI size should be 1.0)
+	virtual F32 getSystemUISize() { return 1.0; }
 protected:
 	LLWindow(LLWindowCallbacks* callbacks, BOOL fullscreen, U32 flags);
 	virtual ~LLWindow();
diff --git a/indra/llwindow/llwindowwin32.cpp b/indra/llwindow/llwindowwin32.cpp
index 875ffe4cd4..2a39029eee 100644
--- a/indra/llwindow/llwindowwin32.cpp
+++ b/indra/llwindow/llwindowwin32.cpp
@@ -78,6 +78,31 @@ LPWSTR gIconResource = IDI_APPLICATION;
 
 LLW32MsgCallback gAsyncMsgCallback = NULL;
 
+#ifndef DPI_ENUMS_DECLARED
+
+typedef enum PROCESS_DPI_AWARENESS {
+	PROCESS_DPI_UNAWARE = 0,
+	PROCESS_SYSTEM_DPI_AWARE = 1,
+	PROCESS_PER_MONITOR_DPI_AWARE = 2
+} PROCESS_DPI_AWARENESS;
+
+typedef enum MONITOR_DPI_TYPE {
+	MDT_EFFECTIVE_DPI = 0,
+	MDT_ANGULAR_DPI = 1,
+	MDT_RAW_DPI = 2,
+	MDT_DEFAULT = MDT_EFFECTIVE_DPI
+} MONITOR_DPI_TYPE;
+
+#endif
+
+typedef HRESULT(STDAPICALLTYPE *SetProcessDpiAwarenessType)(_In_ PROCESS_DPI_AWARENESS value);
+
+typedef HRESULT(STDAPICALLTYPE *GetDpiForMonitorType)(
+	_In_ HMONITOR hmonitor,
+	_In_ MONITOR_DPI_TYPE dpiType,
+	_Out_ UINT *dpiX,
+	_Out_ UINT *dpiY);
+
 //
 // LLWindowWin32
 //
@@ -3878,6 +3903,46 @@ BOOL LLWindowWin32::handleImeRequests(U32 request, U32 param, LRESULT *result)
 	return FALSE;
 }
 
+F32 LLWindowWin32::getSystemUISize()
+{
+	float scale_value = 0;
+	HWND hWnd = (HWND)getPlatformWindow();
+	HDC hdc = GetDC(hWnd);
+	HMONITOR hMonitor;
+
+	HMODULE hShcore = LoadLibrary(L"shcore.dll");
+
+	if (hShcore != NULL)
+	{
+		SetProcessDpiAwarenessType pSPDA;
+		pSPDA = (SetProcessDpiAwarenessType)GetProcAddress(hShcore, "SetProcessDpiAwareness");
+		GetDpiForMonitorType pGDFM;
+		pGDFM = (GetDpiForMonitorType)GetProcAddress(hShcore, "GetDpiForMonitor");
+		if (pSPDA != NULL && pGDFM != NULL)
+		{
+			pSPDA(PROCESS_PER_MONITOR_DPI_AWARE);
+			POINT    pt;
+			UINT     dpix = 0, dpiy = 0;
+			HRESULT  hr = E_FAIL;
+
+			// Get the DPI for the main monitor, and set the scaling factor
+			pt.x = 1;
+			pt.y = 1;
+			hMonitor = MonitorFromPoint(pt, MONITOR_DEFAULTTONEAREST);
+			hr = pGDFM(hMonitor, MDT_EFFECTIVE_DPI, &dpix, &dpiy);
+			scale_value = dpix / 96.0f;
+		}
+	}
+	else
+	{
+		LL_WARNS() << "Could not load shcore.dll library (included by <ShellScalingAPI.h> from Win 8.1 SDK). Using legacy DPI awareness API of Win XP/7" << LL_ENDL;
+		scale_value = GetDeviceCaps(hdc, LOGPIXELSX) / 96.0f;
+	}
+
+	ReleaseDC(hWnd, hdc);
+	return scale_value;
+}
+
 //static
 std::vector<std::string> LLWindowWin32::getDynamicFallbackFontList()
 {
diff --git a/indra/llwindow/llwindowwin32.h b/indra/llwindow/llwindowwin32.h
index 1a775eadaf..1386321912 100644
--- a/indra/llwindow/llwindowwin32.h
+++ b/indra/llwindow/llwindowwin32.h
@@ -110,6 +110,8 @@ public:
 	/*virtual*/ void interruptLanguageTextInput();
 	/*virtual*/ void spawnWebBrowser(const std::string& escaped_url, bool async);
 
+	/*virtual*/ F32 getSystemUISize();
+
 	LLWindowCallbacks::DragNDropResult completeDragNDropRequest( const LLCoordGL gl_coord, const MASK mask, LLWindowCallbacks::DragNDropAction action, const std::string url );
 
 	static std::vector<std::string> getDynamicFallbackFontList();