Win32 设置窗口透明度 SetLayerTransparent

void SetLayerTransparent(HWND hWnd)
{
    static bool isTransParent = false;
    if (isTransParent == false)
    {
        DWORD exStyle = ::GetWindowLong(hWnd, GWL_EXSTYLE);
        exStyle |= WS_EX_LAYERED;
        ::SetWindowLong(hWnd, GWL_EXSTYLE, exStyle);
        ::SetLayeredWindowAttributes(hWnd, RGB(0, 0, 0), 128, LWA_ALPHA);
        isTransParent = true;
    }
    else
    {
        ::SetLayeredWindowAttributes(hWnd, RGB(0, 0, 0), 255, LWA_ALPHA);
        isTransParent = false;
    }
}