Win32 Dark Mode

Dark.md

Dark Mode APIs.

API Signatures.

ShouldAppsUseDarkMode()

Checks whether system is using dark mode or not.
Signature:

using fnShouldAppsUseDarkMode = bool (WINAPI*)(); // ordinal 132

AllowDarkModeForWindow(In HWND hWnd, In bool allow)

Switches the control's theme to the dark variant if available.
Signature:

using fnAllowDarkModeForWindow = bool (WINAPI*)(HWND hWnd, bool allow); // ordinal 133

SetPreferredAppMode(In PreferredAppMode appMode)

Dark Context menu for the app. I don't know what else this does.
Signature(1903+):

using fnSetPreferredAppMode = PreferredAppMode(WINAPI*)(PreferredAppMode appMode); // ordinal 135, in 1903

PreferredAppMode enum

enum class PreferredAppMode
{
   Default,
   AllowDark,
   ForceDark,
   ForceLight,
   Max
};

Actually using them.

First we need to load uxtheme dll as a HMODULE.

HMODULE hUxtheme = LoadLibraryExW(L"uxtheme.dll", nullptr, LOAD_LIBRARY_SEARCH_SYSTEM32);

Then we need to get the Process Address of the functions. We already know their ordinal numbers.
First initialize a instance of the signature.

fnSetPreferredAppMode SetPreferredAppMode;

then set the process address by using GetProcAddress

SetPreferredAppMode = (fnSetPreferredAppMode)GetProcAddress(hUxtheme, MAKEINTRESOURCEA(135));

You can do like this for any API. Dont forget to free it

FreeLibrary(hUxtheme);

Usage.

Enables dark context menus which change automatically depending on the theme.

SetPreferredAppMode(PreferredAppMode::AllowDark);

Dark Controls:

First we need to know which all controls support Dark Mode.
If you open aero.msstyles in msstylesEditor, you would be able to see a lot of DarkMode elements.


And no you cant just do SetWindowTheme([handle to the control], L"DarkMode_Explorer", NULL);

Button:

SetWindowTheme([handle to the control], L"Explorer", NULL);
AllowDarkModeForWindow([handle to the control], true);
SendMessageW([handle to the control], WM_THEMECHANGED, 0, 0);

Edit:

SetWindowTheme([handle to the control], L"CFD", NULL);
AllowDarkModeForWindow([handle to the control], true);
SendMessageW([handle to the control], WM_THEMECHANGED, 0, 0);

ComboBox:

SetWindowTheme([handle to the control], L"CFD", NULL);
AllowDarkModeForWindow([handle to the control], true);
SendMessageW([handle to the control], WM_THEMECHANGED, 0, 0);

TreeView (maybe):

SetWindowTheme([handle to the control], L"Explorer", NULL);
AllowDarkModeForWindow([handle to the control], true);
SendMessageW([handle to the control], WM_THEMECHANGED, 0, 0);

Dark Scrollbars:

For dark scrollbars you need to iat hook and change the scrollbar theme before its created.
First download this header file and add it to your project.
Then use this function before the creation of HWND.

void FixDarkScrollBar()
{
	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);
			}
		}
	}
}

Hi, thank you for sharing the info.
May I ask how to set the menu bar to dark mode? I've tried to send TB_SETWINDOWTHEME message (DarkMode_Explorer) but nothing changed.

It happen in the original example code as well and not just my project
The menu bar is white by default and dropdown menu always in dark mode

I'm sorry if this isn't the right place to ask.

EDIT: I'm using latest Windows Version
EDIT: End up custom draw the menu bar, Thank you @rounk-ctrl.

Oh, for that you need to custom paint it. i think notepad++ has an implementation.

btw its menu bar not toolbar

I'm calling SetPreferredAppMode(PreferredAppMode::AllowDark) when the windows are already visible. I have to toggle fullscreen on and off to make the change affect menu popups. Is there any way to push the change through programmatically?

you can call that function at the beginning of your app, before any window is created. it will auto change the popup menu theme and stuff if you switch between dark and light

I can't. It's not my app. I'm just plugging in a plugin dll.

https://github.com/jjYBdx4IL/ReaperThemeHackDll