请使用wpf完成一个登录界面的开发

作为AI语言模型，我无法完成图形界面的开发。但是，我可以提供一些WPF登录界面的代码示例供您参考。

XAML代码示例：

<Window x:Class="WpfLoginExample.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Login" Height="350" Width="525">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
        </Grid.RowDefinitions>
        <Label Grid.Row="0" Content="Username" HorizontalAlignment="Left" Margin="50,30,0,0" VerticalAlignment="Top"/>
        <TextBox Grid.Row="0" Margin="120,30,50,0" VerticalAlignment="Top" Name="txtUsername"/>
        <Label Grid.Row="1" Content="Password" HorizontalAlignment="Left" Margin="50,10,0,0" VerticalAlignment="Top"/>
        <PasswordBox Grid.Row="1" Margin="120,10,50,0" VerticalAlignment="Top" Name="txtPassword"/>
        <Button Grid.Row="2" Content="Login" HorizontalAlignment="Center" Margin="0,30,0,0" VerticalAlignment="Top" Width="75" Click="btnLogin_Click"/>
        <Label Grid.Row="3" Name="lblMessage" Content="" HorizontalAlignment="Center" Margin="0,10,0,0" VerticalAlignment="Top"/>
    </Grid>
</Window>

C#代码示例：

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void btnLogin_Click(object sender, RoutedEventArgs e)
    {
        string username = txtUsername.Text;
        string password = txtPassword.Password;

        if (username == "admin" && password == "admin123")
        {
            lblMessage.Content = "Login Successful";
        }
        else
        {
            lblMessage.Content = "Invalid Username or Password";
        }
    }
}

以上示例代码实现了一个简单的登录界面，包括用户名和密码输入框、登录按钮、以及登录结果提示标签。在点击登录按钮时，会验证用户名和密码是否正确，并根据结果更新提示信息。您可以根据需要进行修改和扩展。