C# 将图片显示为隐藏或可见

目标：
当用户开始在文本框txtSearch中键入文本或字符时，图片放大程序将被隐藏并替换为图片picXmark。 默认情况下，picEnlarger将始终显示，直到输入数据应用到文本框txtSearch中。按顺序，文本框中没有数据，然后显示picEnlarger并隐藏picXmark

picEnlarger = new Image();  
picXmark = new Image();

问题：
当用户开始在名为txtSearch的文本框中键入字符时，无法显示图片picXmark并隐藏图片放大程序

picEnlarger = new Image();  
picXmark = new Image();

当我尝试用C#编码以获得此功能时，在运行时不会产生任何效果

picEnlarger = new Image();  
picXmark = new Image();

我尝试使用代码：

picEnlarger = new Image();  
picXmark = new Image();

但没有发生任何影响

picEnlarger = new Image();  
picXmark = new Image();

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Stock.XAML中的XAML代码：

picEnlarger = new Image();  
picXmark = new Image();

<Canvas Height="39.667" Margin="8,0,215.397,0" VerticalAlignment="Top">
    <Button x:Name="btnNewProduct" Content="New" Width="75" Click="btnNewProduct_Click" Height="20.277" RenderTransformOrigin="0.667,1.726" d:LayoutOverrides="VerticalAlignment, Margin" Canvas.Left="0.001" Canvas.Top="18.723" />
    <Button x:Name="btnAddDelivery" Content="Add quantity" Width="75" Click="btnAddDelivery_Click" d:LayoutOverrides="VerticalAlignment, Margin" Height="20.277" Canvas.Left="79.001" Canvas.Top="18.723" />
    <Button x:Name="btnDeleteProduct" Content="Delete" Width="75" RenderTransformOrigin="0.107,1.843" Click="btnDeleteProduct_Click" Height="20.277" Canvas.Left="158.001" d:LayoutOverrides="HorizontalAlignment, VerticalAlignment, Width" Canvas.Top="18.723" />
    <Button x:Name="btnEdit" Content="Edit" Canvas.Left="237.001" Width="75" Canvas.Top="18.723" Click="btnEdit_Click" />
    <TextBox Name="txtSearch" Canvas.Left="391.36" TextWrapping="Wrap" Canvas.Top="18.723" Width="143.243" TextChanged="txtSearch_TextChanged" Text=" Search article" PreviewMouseLeftButtonDown="txtSearch_PreviewMouseLeftButtonDown" TextInput="txtSearch_TextInput">            
        </TextBox>

        <Label Content="Advanced Search" HorizontalAlignment="Left" Canvas.Left="444.289"/>
        <Image x:Name="picXmark" Height="8" Source="/MediaStore;component/Bilder/search_xmark.gif" Stretch="Fill" Width="8" Canvas.Left="519.853" Canvas.Top="24.167" Visibility="Hidden" />
    <Image x:Name="picEnlarger" Height="14" Canvas.Left="513.75" Source="/MediaStore;component/Bilder/search_enlarger2.gif" Stretch="Fill" Canvas.Top="21.527" Width="14" Visibility="Hidden" ImageFailed="picEnlarger_ImageFailed" />

</Canvas>

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从理论上讲，你应该能够仅仅使用触发器，例如

picEnlarger = new Image();  
picXmark = new Image();

---

输入文本后，一个图像将可见，而另一个图像将隐藏。

感谢您的帮助。我需要更多的补充来访问此网站以实现我的功能“”

picEnlarger = new Image();  
picXmark = new Image();