我正在使用jCaptcha.js为我的应用程序生成验证码。一旦完成注册和注销并尝试注册新帐户，它就可以完美地首次工作。画布不会打印任何显示为空白的内容，因此，它会循环循环，因为我设置了检查以查看是否为空白。

private async void PlayPlaylist(string value)
{
    if (PlayButtonmode == 1)
    {
        int startPosition;
        //Playing playlist from selected item if user selected one. (first item if he didn't)
        if (PlaylistSelectedItem == null) startPosition = 0;
        else startPosition = Playlist.IndexOf(playlistSelectedItem);
        if (audio.IsPlaying) audio.Stop();
        PlaylistSelectedItem = Playlist[startPosition];
        audio.Load(GetStreamFromFile(PlaylistSelectedItem.Name + ".wav"));
        audio.Play();
        audio.PlaybackEnded += Audio_PlaybackEnded;
    }
    else if (PlayButtonmode == 2)
        audio.Play();
    else
    {
        if (audio.IsPlaying) audio.Pause();
    }
    ChangeButtonmode(PlayButtonmode);
}

private void ChangeButtonmode(int senderMode)
{
    if (senderMode == 1 || senderMode == 2)
    {
        PlayButtonText = "PAUSE";
        PlayButtonImage = "pause_icon.png";
        PlayButtonmode = 0;
    }
    else
    {
        PlayButtonText = "PLAY";
        PlayButtonImage = "play_icon.png";
        if (senderMode == 3) PlayButtonmode = 1; 
        else PlayButtonmode = 2;
    }
    NotifyButtonChange();
}

private void Audio_PlaybackEnded(object sender,EventArgs e)
{
    //Check if next playlist element exists
    if(Playlist.IndexOf(PlaylistSelectedItem) + 1 < Playlist.Count)
    {
        PlaylistSelectedItem = Playlist[Playlist.IndexOf(PlaylistSelectedItem) + 1];
        if (audio.IsPlaying) audio.Stop();
        audio.Load(GetStreamFromFile(PlaylistSelectedItem.Name + ".wav"));
        audio.Play();
        audio.PlaybackEnded += Audio_PlaybackEnded;
    }else if(audio.IsPlaying) audio.Stop();   
}


private void StopAudio()
{
    if (audio.IsPlaying)
        audio.Stop();
    ChangeButtonmode(3);
}

jCaptcha.js

if ($('.jCaptchaText')[0].toDataURL() != $('#blankCaptcha')[0].toDataURL())
isCaptchaBlank = false;