DarkMode.cpp

#include "IatHook.h"
#include "DarkMode.h"

fnSetWindowCompositionAttribute _SetWindowCompositionAttribute = nullptr;
fnShouldAppsUseDarkMode _ShouldAppsUseDarkMode = nullptr;
fnAllowDarkModeForWindow _AllowDarkModeForWindow = nullptr;
fnAllowDarkModeForApp _AllowDarkModeForApp = nullptr;
fnFlushMenuThemes _FlushMenuThemes = nullptr;
fnRefreshImmersiveColorPolicyState _RefreshImmersiveColorPolicyState = nullptr;
fnIsDarkModeAllowedForWindow _IsDarkModeAllowedForWindow = nullptr;
fnGetIsImmersiveColorUsingHighContrast _GetIsImmersiveColorUsingHighContrast = nullptr;
fnOpenNcThemeData _OpenNcThemeData = nullptr;
// 1903 18362
fnShouldSystemUseDarkMode _ShouldSystemUseDarkMode = nullptr;
fnSetPreferredAppMode _SetPreferredAppMode = nullptr;
fnSetWindowTheme _SetWindowTheme = nullptr;

bool g_darkModeSupported = false;
bool g_darkModeEnabled = false;
DWORD g_buildNumber = 0;

bool AllowDarkModeForWindow(HWND hWnd, bool allow)
{
	if (g_darkModeSupported)
		return _AllowDarkModeForWindow(hWnd, allow);
	return false;
}

bool IsHighContrast()
{
	HIGHCONTRASTW highContrast = { sizeof(highContrast) };
	if (SystemParametersInfoW(SPI_GETHIGHCONTRAST, sizeof(highContrast), &highContrast, FALSE))
		return highContrast.dwFlags & HCF_HIGHCONTRASTON;
	return false;
}

void RefreshTitleBarThemeColor(HWND hWnd)
{
	BOOL dark = FALSE;
	if (_IsDarkModeAllowedForWindow(hWnd) &&
		_ShouldAppsUseDarkMode() &&
		!IsHighContrast())
	{
		dark = TRUE;
	}
	if (g_buildNumber < 18362)
		SetPropW(hWnd, L"UseImmersiveDarkModeColors", reinterpret_cast<HANDLE>(static_cast<INT_PTR>(dark)));
	else if (_SetWindowCompositionAttribute)
	{
		WINDOWCOMPOSITIONATTRIBDATA data = { WCA_USEDARKMODECOLORS, &dark, sizeof(dark) };
		_SetWindowCompositionAttribute(hWnd, &data);
	}
}

bool IsColorSchemeChangeMessage(LPARAM lParam)
{
	bool is = false;
	if (lParam && CompareStringOrdinal(reinterpret_cast<LPCWCH>(lParam), -1, L"ImmersiveColorSet", -1, TRUE) == CSTR_EQUAL)
	{
		_RefreshImmersiveColorPolicyState();
		is = true;
	}
	_GetIsImmersiveColorUsingHighContrast(IHCM_REFRESH);
	return is;
}

bool IsColorSchemeChangeMessage(UINT message, LPARAM lParam)
{
	if (message == WM_SETTINGCHANGE)
		return IsColorSchemeChangeMessage(lParam);
	return false;
}

void AllowDarkModeForApp(bool allow)
{
	if (_AllowDarkModeForApp)
		_AllowDarkModeForApp(allow);
	else if (_SetPreferredAppMode)
		_SetPreferredAppMode(allow ? AllowDark : Default);
}

void FixDarkScrollBar()
{
	// Disable this, doesn't look good.
	return;

	HMODULE hComctl = LoadLibraryExW(L"comctl32.dll", nullptr, LOAD_LIBRARY_SEARCH_SYSTEM32);
	if (hComctl)
	{
		auto addr = FindDelayLoadThunkInModule(hComctl, "uxtheme.dll", 49); // OpenNcThemeData
		if (addr)
		{
			DWORD oldProtect;
			if (VirtualProtect(addr, sizeof(IMAGE_THUNK_DATA), PAGE_READWRITE, &oldProtect))
			{
				auto MyOpenThemeData = [](HWND hWnd, LPCWSTR classList) -> HTHEME {
					if (wcscmp(classList, L"ScrollBar") == 0)
					{
						hWnd = nullptr;
						classList = L"Explorer::ScrollBar";
					}
					return _OpenNcThemeData(hWnd, classList);
				};

				addr->u1.Function = reinterpret_cast<ULONG_PTR>(static_cast<fnOpenNcThemeData>(MyOpenThemeData));
				VirtualProtect(addr, sizeof(IMAGE_THUNK_DATA), oldProtect, &oldProtect);
			}
		}
	}
}

void DarkModeInitDialog(HWND hDlg) {
	if (g_darkModeSupported) {
		_SetWindowTheme(GetDlgItem(hDlg, IDOK), L"Explorer", nullptr);
		SendMessageW(hDlg, WM_THEMECHANGED, 0, 0);
	}
}

LRESULT DarkModeDlgProc(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam) {
	constexpr COLORREF darkBkColor = 0x383838;
	constexpr COLORREF darkTextColor = 0xFFFFFF;
	static HBRUSH hbrBkgnd = nullptr;

	switch (message) {
		case WM_CTLCOLORDLG:
		case WM_CTLCOLORSTATIC:
		{
			if (g_darkModeSupported && g_darkModeEnabled)
			{
				HDC hdc = reinterpret_cast<HDC>(wParam);
				SetTextColor(hdc, darkTextColor);
				SetBkColor(hdc, darkBkColor);
				if (!hbrBkgnd)
					hbrBkgnd = CreateSolidBrush(darkBkColor);
				return reinterpret_cast<INT_PTR>(hbrBkgnd);
			}
			break;
		}
		case WM_SETTINGCHANGE:
		{
			if (g_darkModeSupported && IsColorSchemeChangeMessage(lParam))
				SendMessageW(hDlg, WM_THEMECHANGED, 0, 0);
			break;
		}
		case WM_THEMECHANGED:
		{
			if (g_darkModeSupported)
			{
				_AllowDarkModeForWindow(hDlg, g_darkModeEnabled);
				RefreshTitleBarThemeColor(hDlg);

				HWND hButton = GetDlgItem(hDlg, IDOK);
				_AllowDarkModeForWindow(hButton, g_darkModeEnabled);
				SendMessageW(hButton, WM_THEMECHANGED, 0, 0);

				UpdateWindow(hDlg);
			}
			break;
		}
	}
	return FALSE;
}

bool IsDarkModeEnabled() {
	return g_darkModeEnabled;
}

constexpr bool CheckBuildNumber(DWORD buildNumber)
{
	// TODO: This is BS.

	return (buildNumber == 17763 || // 1809
		buildNumber == 18362 || // 1903
		buildNumber == 18363 || // 1909
		buildNumber >= 19041);  // Windows 11
}

void InitDarkMode()
{
	auto RtlGetNtVersionNumbers = reinterpret_cast<fnRtlGetNtVersionNumbers>(GetProcAddress(GetModuleHandleW(L"ntdll.dll"), "RtlGetNtVersionNumbers"));
	if (RtlGetNtVersionNumbers)
	{
		DWORD major, minor;
		RtlGetNtVersionNumbers(&major, &minor, &g_buildNumber);
		g_buildNumber &= ~0xF0000000;
		if (major == 10 && minor == 0 && CheckBuildNumber(g_buildNumber))
		{
			HMODULE hUxtheme = LoadLibraryExW(L"uxtheme.dll", nullptr, LOAD_LIBRARY_SEARCH_SYSTEM32);
			if (hUxtheme)
			{
				_OpenNcThemeData = reinterpret_cast<fnOpenNcThemeData>(GetProcAddress(hUxtheme, MAKEINTRESOURCEA(49)));
				_RefreshImmersiveColorPolicyState = reinterpret_cast<fnRefreshImmersiveColorPolicyState>(GetProcAddress(hUxtheme, MAKEINTRESOURCEA(104)));
				_GetIsImmersiveColorUsingHighContrast = reinterpret_cast<fnGetIsImmersiveColorUsingHighContrast>(GetProcAddress(hUxtheme, MAKEINTRESOURCEA(106)));
				_ShouldAppsUseDarkMode = reinterpret_cast<fnShouldAppsUseDarkMode>(GetProcAddress(hUxtheme, MAKEINTRESOURCEA(132)));
				_AllowDarkModeForWindow = reinterpret_cast<fnAllowDarkModeForWindow>(GetProcAddress(hUxtheme, MAKEINTRESOURCEA(133)));

				auto ord135 = GetProcAddress(hUxtheme, MAKEINTRESOURCEA(135));
				if (g_buildNumber < 18362)
					_AllowDarkModeForApp = reinterpret_cast<fnAllowDarkModeForApp>(ord135);
				else
					_SetPreferredAppMode = reinterpret_cast<fnSetPreferredAppMode>(ord135);

				//_FlushMenuThemes = reinterpret_cast<fnFlushMenuThemes>(GetProcAddress(hUxtheme, MAKEINTRESOURCEA(136)));
				_IsDarkModeAllowedForWindow = reinterpret_cast<fnIsDarkModeAllowedForWindow>(GetProcAddress(hUxtheme, MAKEINTRESOURCEA(137)));

				_SetWindowCompositionAttribute = reinterpret_cast<fnSetWindowCompositionAttribute>(GetProcAddress(GetModuleHandleW(L"user32.dll"), "SetWindowCompositionAttribute"));
				_SetWindowTheme = reinterpret_cast<fnSetWindowTheme>(GetProcAddress(hUxtheme, "SetWindowTheme"));

				if (_OpenNcThemeData &&
					_RefreshImmersiveColorPolicyState &&
					_ShouldAppsUseDarkMode &&
					_AllowDarkModeForWindow &&
					(_AllowDarkModeForApp || _SetPreferredAppMode) &&
					//_FlushMenuThemes &&
					_IsDarkModeAllowedForWindow)
				{
					g_darkModeSupported = true;

					AllowDarkModeForApp(true);
					_RefreshImmersiveColorPolicyState();

					g_darkModeEnabled = _ShouldAppsUseDarkMode() && !IsHighContrast();

					FixDarkScrollBar();
				}
			}
		}
	}
}