setHighDPIAware()

setHighDPIAware.c

#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;
#ifndef _DPI_AWARENESS_CONTEXTS_
typedef enum DPI_AWARENESS_CONTEXT {
	DPI_AWARENESS_INVALID,
	DPI_AWARENESS_UNAWARE,
	DPI_AWARENESS_SYSTEM_AWARE,
	DPI_AWARENESS_PER_MONITOR_AWARE
} DPI_AWARENESS_CONTEXT;
#endif
#define DPI_AWARENESS_CONTEXT_UNAWARE              ((DPI_AWARENESS_CONTEXT)-1)
#define DPI_AWARENESS_CONTEXT_SYSTEM_AWARE         ((DPI_AWARENESS_CONTEXT)-2)
#define DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE    ((DPI_AWARENESS_CONTEXT)-3)
#define DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2 ((DPI_AWARENESS_CONTEXT)-4)
#define DPI_AWARENESS_CONTEXT_UNAWARE_GDISCALED    ((DPI_AWARENESS_CONTEXT)-5)
#define DPI_ENUMS_DECLARED
#endif // (DPI_ENUMS_DECLARED)

typedef WINUSERAPI BOOL(WINAPI *pSetProcessDpiAwareness)(PROCESS_DPI_AWARENESS value);
typedef WINUSERAPI BOOL(WINAPI *pSetProcessDPIAware)();
typedef WINUSERAPI BOOL(WINAPI *pSetThreadDpiAwarenessContext)(DPI_AWARENESS_CONTEXT value);
typedef WINUSERAPI BOOL(WINAPI *pSetProcessDpiAwarenessContext)(DPI_AWARENESS_CONTEXT value);
bool setHighDPIAwareWin10()
{
	// This fixes the issue where if you change the OS DPI scale while logged in, the title
	// bar is the wrong size.
	HMODULE lib = LoadLibrary("User32.dll");
	if (!lib) {
		return false;
	}

	bool ret = false;
	// Try Win10 build 1703+ method
	pSetProcessDpiAwarenessContext pfnSetProc = (pSetProcessDpiAwarenessContext)GetProcAddress(lib, "SetProcessDpiAwarenessContext");
	if (pfnSetProc) {
		ret = (NULL != pfnSetProc(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2));
		// printf("Win10 1703 HighDPI SetProcessDpiAwarenessContext() success=%d\n", ret);
	}
	if (!ret) {
		// Try Win10 build 1607+ method
		// Older method, has problems on buggy NVIDIA drivers
		pSetThreadDpiAwarenessContext pfnSet = (pSetThreadDpiAwarenessContext)GetProcAddress(lib, "SetThreadDpiAwarenessContext");
		if (pfnSet) {
			ret = (NULL != pfnSet(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2));
			// printf("Win10 1607 HighDPI SetThreadDpiAwarenessContext() success=%d\n", ret);
		}
	}
	FreeLibrary(lib);
	return ret;
}
static bool setHighDPIAwareWin81()
{
	HMODULE shcore = LoadLibrary("Shcore.dll");
	if (!shcore) {
		printf("Shcore.dll failed to load\n");
		return false;
	}

	pSetProcessDpiAwareness pfnSetProcessDpiAwareness = (pSetProcessDpiAwareness)GetProcAddress(shcore, "SetProcessDpiAwareness");
	bool ret = false;
	if (pfnSetProcessDpiAwareness) {
		// Note: on Win8, this is returning a bool, not an hresult, to this check is backwards?
		ret = (S_OK == pfnSetProcessDpiAwareness(PROCESS_PER_MONITOR_DPI_AWARE));
		// printf("Win81 HighDPI SetProcessDpiAwareness() success=%d\n", ret);
	}
	FreeLibrary(shcore);
	return ret;
}
void setHighDPIAware()
{
	static bool doneonce = false;
	if (doneonce)
		return;
	doneonce = true;
	if (setHighDPIAwareWin10()) {
		return;
	}
	if (setHighDPIAwareWin81()) {
		return;
	}
	HMODULE user32 = LoadLibrary("user32.dll");
	if (!user32)
		return;
	pSetProcessDPIAware pfnSetProcessDPIAware = (pSetProcessDPIAware)GetProcAddress(user32, "SetProcessDPIAware");
	bool ret = false;
	if (pfnSetProcessDPIAware) {
		ret = !!pfnSetProcessDPIAware();
		// printf("HighDPI SetProcessDPIAware() success=%d\n", ret);
	}
	FreeLibrary(user32);
	return;
}