WPF Textbox 控件绑定数据即时更新UpdateSourceTrigger=PropertyChanged

 Textbox 控件绑定数据类型为 doubie类型时，如果触发条件为UpdateSourceTrigger=PropertyChanged时，无法输入小数点。

解决方案：

方法一：关闭数据一至检查

       System.Windows.FrameworkCompatibilityPreferences.KeepTextBoxDisplaySynchronizedWithTextProperty = false;

方法二：写转换器

public class StringToDoubleConverter : IValueConverter
  {

    private static string backValue;
    private static bool backBool;

    /// <summary>
    /// 转换值。
    /// </summary>
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
      var str = value?.ToString();
      if (string.IsNullOrEmpty(str))
        return 0d;

      var dou = str.ToNuDouble();
      if (dou is null)
      {
        return 0d;
      }
      else
      {
        if (!backBool && backValue is not null)
        {
          var l = str.Last().ToString();
          var newstr = backValue + l;
          backValue = null;
          backBool = false;
          return newstr.ToDouble();
        }
        if (backBool)
        {
          backBool = false;
        }
      }

      return dou.Value;
    }
    /// <summary>
    /// 转换值。
    /// </summary>
    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
      var str = value?.ToString();
      if (string.IsNullOrEmpty(str))
        return 0d;


      var dou = str.ToNuDouble();
      if (dou is null)
      {
        return 0d;
      }
      else
      {
        if (str.Contains("."))
        {
          backValue = str;
          backBool = true;
        }
      }

      return dou.Value;
    }
  }