Win32: Mark OC "DPI aware" (#891)

Technically this mark is incorrect; we do not handle things differently
on high DPI settings. On the other hand, marking OC DPI aware means that
Windows won't try to scale our drawing, clipping menus and rendering in
the process.

Somewhere in the future, OpenClonk should also add proper DPI awareness
and change the default zoom and menu scaling to match.

src/game/ClonkMain.cpp

@@ -8,7 +8,7 @@
  * Copyright (c) 2006  Armin Burgmeier
  * Copyright (c) 2007  Julian Raschke
  * Copyright (c) 2010  Benjamin Herr
- * Copyright (c) 2011  Nicolas Hake
+ * Copyright (c) 2011-2012  Nicolas Hake
  * Copyright (c) 2001-2009, RedWolf Design GmbH, http://www.clonk.de
  *
  * Portions might be copyrighted by other authors who have contributed
@@ -48,6 +48,23 @@ int WINAPI WinMain (HINSTANCE hInst,
 	_CrtSetDbgFlag( _CrtSetDbgFlag( _CRTDBG_REPORT_FLAG ) | _CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF);
 #endif
 
+	// This should be handled in an application manifest, but that is
+	// decidedly non-trivial to do portably across compilers and compiler
+	// versions, so we do it in code instead.
+	// Also we aren't really DPI aware (we'd have to default ingame zoom
+	// differently and scale the menus), but this is better than clipping.
+	// Fixes #891.
+	HMODULE user32 = LoadLibrary(L"user32");
+	if (user32)
+	{
+		typedef BOOL (WINAPI *SETPROCESSDPIAWAREPROC)();
+		SETPROCESSDPIAWAREPROC SetProcessDPIAware =
+			reinterpret_cast<SETPROCESSDPIAWAREPROC>(GetProcAddress(user32, "SetProcessDPIAware"));
+		if (SetProcessDPIAware)
+			SetProcessDPIAware();
+		FreeLibrary(user32);
+	}
+
 	InstallCrashHandler();
 
 	// Split wide command line to wide argv array