获取用户名

总体而言还算简单，只需要以下代码：

var userName = Environment.UserName;
Console.WriteLine(userName);

获取用户的头像

以下方法需要调用Win32的DLL，因此支持的站点仅为Windows

using Microsoft.UI.Xaml.Media;
using Microsoft.UI.Xaml.Media.Imaging;
using System.Runtime.InteropServices;
using System.Text;

public static partial class UserTileHelper
{
    [DllImport("shell32.dll", EntryPoint = "#261",
               CharSet = CharSet.Unicode, PreserveSig = false)]
    public static extern void GetUserTilePath(string? username, uint whatever, StringBuilder picpath, int maxLength);

    public static string GetUserTilePath(string? username = null)
    {
        var sb = new StringBuilder(1000);
        GetUserTilePath(username, 0x80000000, sb, sb.Capacity);
        return sb.ToString();
    }

    public static ImageSource GetUserTile(string? username = null) => new BitmapImage(new Uri(GetUserTilePath(username)));
}

然后使用的时候只需要调用以下代码：

var userTile = UserTileHelper.GetUserTile();