我如何找出一个字符串是否包含此SpriteFont无法解析的字符？

Question

当绘制SpriteFont中不支持的字符时，出现异常。 TextboxString是用软键盘输入的字符串。玩家可以在我的ios/android应用程序中使用软键盘输入显示名称，密码和电子邮件地址。

    private async Task<string> ShowKeyboard(string messageboxtitle, string messageboxdescription, string text, bool ispassword)
    {
        string TextboxString = "";
        await Task.Run(async () =>
        {           
            var result = await KeyboardInput.Show(messageboxtitle, messageboxdescription, text, ispassword);
            if (null != result)
            {
                TextboxString = result;
            }
        });

        KeyboardActiv = false;

        return TextboxString;
    }

例如，如果TextboxString = "Player_磨";，则由于我不支持汉字而出现异常。我只想支持英语，西班牙语，意大利语，法语，德语和葡萄牙语字符。

spriteBatch.DrawString(Font, TextboxString, new Vector2(100, 500), Microsoft.Xna.Framework.Color.Black);

已抛出System.ArgumentException
文本包含的字符此SpriteFont无法解决。参数名称：文本

如何确定玩家是否输入了spriteFont不支持的角色？

如果播放器输入了不受支持的字符，我想在我的应用程序中显示一条消息。

我的spriteFont文件：

<?xml version="1.0" encoding="utf-8"?>
<!--
This file contains an xml description of a font, and will be read by the XNA
Framework Content Pipeline. Follow the comments to customize the appearance
of the font in your game, and to change the characters which are available to draw
with.
-->
<XnaContent xmlns:Graphics="Microsoft.Xna.Framework.Content.Pipeline.Graphics">
  <Asset Type="Graphics:FontDescription">

    <!--
    Modify this string to change the font that will be imported.
    -->
    <FontName>Arial</FontName>

    <!--
    Size is a float value, measured in points. Modify this value to change
    the size of the font.
    -->
    <Size>28</Size>

    <!--
    Spacing is a float value, measured in pixels. Modify this value to change
    the amount of spacing in between characters.
    -->
    <Spacing>0</Spacing>

    <!--
    UseKerning controls the layout of the font. If this value is true, kerning information
    will be used when placing characters.
    -->
    <UseKerning>true</UseKerning>

    <!--
    Style controls the style of the font. Valid entries are "Regular", "Bold", "Italic",
    and "Bold, Italic", and are case sensitive.
    -->
    <Style>Regular</Style>

    <!--
    If you uncomment this line, the default character will be substituted if you draw
    or measure text that contains characters which were not included in the font.
    -->
    <!-- <DefaultCharacter>?</DefaultCharacter> -->

    <!--
    CharacterRegions control what letters are available in the font. Every
    character from Start to End will be built and made available for drawing. The
    default range is from 32, (ASCII space), to 126, ('~'), covering the basic Latin
    character set. The characters are ordered according to the Unicode standard.
    See the documentation for more information.
    -->
    <CharacterRegions>
      <CharacterRegion>
      <Start>&#32;</Start>
      <End>&#512;</End>
      </CharacterRegion>
      <CharacterRegion>
      <!-- Apostrophe 8217 -->
      <Start>&#8216;</Start>
      <End>&#8222;</End>
      </CharacterRegion>
      <CharacterRegion>
      <!-- Currency symbols -->
      <Start>&#8352;</Start>
      <End>&#8378;</End>
      </CharacterRegion>
    </CharacterRegions>
  </Asset>
</XnaContent>