fn set_dark_mode_for_window()

in src/platform_impl/windows/dark_mode.rs [93:135]

• 32 lines of code
• 2 McCabe index (conditional complexity)

fn set_dark_mode_for_window(hwnd: HWND, is_dark_mode: bool) -> bool {
    // Uses Windows undocumented API SetWindowCompositionAttribute,
    // as seen in win32-darkmode example linked at top of file.

    type SetWindowCompositionAttribute =
        unsafe extern "system" fn(HWND, *mut WINDOWCOMPOSITIONATTRIBDATA) -> BOOL;

    #[allow(non_snake_case)]
    type WINDOWCOMPOSITIONATTRIB = u32;
    const WCA_USEDARKMODECOLORS: WINDOWCOMPOSITIONATTRIB = 26;

    #[allow(non_snake_case)]
    #[repr(C)]
    struct WINDOWCOMPOSITIONATTRIBDATA {
        Attrib: WINDOWCOMPOSITIONATTRIB,
        pvData: PVOID,
        cbData: SIZE_T,
    }

    lazy_static! {
        static ref SET_WINDOW_COMPOSITION_ATTRIBUTE: Option<SetWindowCompositionAttribute> =
            get_function!("user32.dll", SetWindowCompositionAttribute);
    }

    if let Some(set_window_composition_attribute) = *SET_WINDOW_COMPOSITION_ATTRIBUTE {
        unsafe {
            // SetWindowCompositionAttribute needs a bigbool (i32), not bool.
            let mut is_dark_mode_bigbool = is_dark_mode as BOOL;

            let mut data = WINDOWCOMPOSITIONATTRIBDATA {
                Attrib: WCA_USEDARKMODECOLORS,
                pvData: &mut is_dark_mode_bigbool as *mut _ as _,
                cbData: std::mem::size_of_val(&is_dark_mode_bigbool) as _,
            };

            let status = set_window_composition_attribute(hwnd, &mut data as *mut _);

            status != FALSE
        }
    } else {
        false
    }
}