如何限制ValueConverter中的最大字符數

Question

如何限制此TextBlock中的字符數？
例如：它最多隻能顯示5個字符。

<TextBlock > 
    <Run Text="Tender Amount:"/> 
    <Run Text="{Binding TenderAmount, 
       Converter={StaticResource StringFormatConverter}, 
       ConverterParameter='{}{0:C}'}" /> 
</TextBlock> 

下面的代碼在我的轉換

public sealed class StringFormatConverter : IValueConverter 
{ 
    public object Convert(object value, Type targetType, object parameter, string language) 
    { 
     if (value == null) 
      return null; 

     if (parameter == null) 
      return value; 

     return string.Format((string)parameter, value); 
    } 

    public object ConvertBack(object value, Type targetType, object parameter, 
     string language) 
    { 
     throw new NotImplementedException(); 
    } 
} 

Answer 1

使用此：

public sealed class StringFormatConverter : IValueConverter 
{ 
    public int MaxLength { get; set; } 

    public object Convert(object value, Type targetType, object parameter, string language) 
    { 
     if (value == null) 
      return null; 

     if (parameter == null) 
      return value; 

     var result = string.Format((string)parameter, value); 

     if (MaxLength > 0) 
      result = result.Substring(0, MaxLength); 

     return result; 
    } 

    public object ConvertBack(object value, Type targetType, object parameter, 
     string language) 
    { 
     throw new NotImplementedException(); 
    } 
} 

如果你宣佈你的轉換器資源，做到這一點：

<stuff:StringFormatConverter x:Key="StringFormatConverter" MaxLength="5" />