1、效果如下图，点击图片可更新验证码（其实图片就是一个Button的背景图）。

2、主要使通过用户控件创建，UCVerificationCode.xaml代码如下。

<UserControl x:Class="UC.UCVerificationCode"xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:local="clr-namespace:RegisterWPF.UC"xmlns:hc="https://handyorg.github.io/handycontrol"mc:Ignorable="d" Width="Auto"Height="Auto" Loaded="UCVerificationCode_OnLoaded"><Grid>     <Button x:Name="btnVerificationCode" Width="100" Height="40" BorderThickness="0" Click="BtnVerificationCode_OnClick"/></Grid>
</UserControl>

3、UCVerificationCode.xaml.cs代码如下。

    /// <summary>/// UCVerificationCode.xaml 的交互逻辑/// </summary>public partial class UCVerificationCode : UserControl{public string VerificationCode { get; set; }public UCVerificationCode(){InitializeComponent();}/// <summary>/// 用户控件加载完成/// </summary>/// <param name="sender"></param>/// <param name="e"></param>private void UCVerificationCode_OnLoaded(object sender, RoutedEventArgs e){GetVerificationCode();}/// <summary>/// 获取验证码/// </summary>public void GetVerificationCode(){using (MemoryStream outStream = new MemoryStream()){Bitmap bitmap = CreateVerificationCode(out string code);bitmap.Save(outStream, ImageFormat.Bmp);BitmapImage bitmapImage = new BitmapImage();bitmapImage.BeginInit();bitmapImage.StreamSource = new MemoryStream(outStream.ToArray());bitmapImage.EndInit();ImageBrush imgBrush = new ImageBrush(bitmapImage);btnVerificationCode.Background = imgBrush;VerificationCode = code;Debug.WriteLine(code);Debug.WriteLine(VerificationCode);}}/// <summary>/// 生成验证码图片/// </summary>/// <param name="code"></param>/// <returns></returns>public static Bitmap CreateVerificationCode(out string code){//建立Bitmap对象，绘图Bitmap bitmap = new Bitmap(200, 60);Graphics graph = Graphics.FromImage(bitmap);graph.FillRectangle(new SolidBrush(System.Drawing.Color.White), 0, 0, 200, 60);Font font = new Font(System.Drawing.FontFamily.GenericSansSerif,  48,System.Drawing.FontStyle.Bold, GraphicsUnit.Pixel);Random r = new Random();string letters = "ABCDEFGHIJKLMNPQRSTUVWXYZ0123456789";StringBuilder sb = new StringBuilder();//添加随机的五个字母for (int x = 0; x < 4; x++){string letter = letters.Substring(r.Next(0, letters.Length - 1), 1);sb.Append(letter);graph.DrawString(letter, font, new SolidBrush(Color.Black), x * 38, r.Next(0, 15));}code = sb.ToString();//混淆背景Pen linePen = new Pen(new SolidBrush(Color.Black), 2);for (int x = 0; x < 6; x++)graph.DrawLine(linePen, new Point(r.Next(0, 199), r.Next(0, 59)), new Point(r.Next(0, 199), r.Next(0, 59)));return bitmap;}/// <summary>/// 刷新验证码/// </summary>/// <param name="sender"></param>/// <param name="e"></param>private void BtnVerificationCode_OnClick(object sender, RoutedEventArgs e){GetVerificationCode();}}

4、引用时。

<localuc:UCVerificationCode VerticalAlignment="Center" HorizontalContentAlignment="Center" Margin="0" Padding="0" BorderThickness="0"/>