我想了解有关WPF绑定文本框的内容

Question

I am trying to make a logger system with WPF in xaml. I made the below biding code:

<TextBlock x:Name="textBlock"
           HorizontalAlignment="Left"
           Margin="10,194,0,0"
           TextWrapping="Wrap"
           VerticalAlignment="Top"
           Height="51"
           Width="366"
           Text="{Binding LogView,
                          Source={StaticResource logViewModel},
                          UpdateSourceTrigger=PropertyChanged}" />

The Binding text is working correctly, but in the textbox, string is updated only on the first line in the textbox. The string should be updated on the next line, and I can't use append string like the below code because I will be parsing Character(ex. D,E,I) and then changing the string color:

mLogViewStr+=value;

help me please...

logViewModel :

 namespace StretcherUI.Device
    {
        class LogViewModel : ILogHandler,
                             INotifyPropertyChanged
        {
            public event PropertyChangedEventHandler PropertyChanged;
            static string savePath = @"d:\log.txt";
            const int logListSize = 500;
            public LogViewModel()
            {
                Logger.sLogHandler = this;
            }


            private string mLogViewStr;
            public string LogView
            {
                get { return mLogViewStr; }
                set
                {
                    mLogViewStr = value;               
                }
            }

            protected void OnPropertyChanged(string propertyName)
            {
                PropertyChanged?.Invoke(
                                    this,
                                    new PropertyChangedEventArgs(propertyName));
            }

            public void onLog(string logFmt, params object[] arg)
            {
                LogView = string.Format(logFmt, arg);
            }
        }
    }

Answer 1

you should call OnPropertyChanged in your public setter, that way WPF view can understand that it has pending update

  public string LogView
            {
                get { return mLogViewStr; }
                set
                {
                    mLogViewStr = value;
                    OnPropertyChanged("LogView");
                }
            }

Answer 2

Binding from model to view work only if you notify View. So in order to notify view, model should implement INotifyPropertyChanged (which you did) and call PropertyChanged every time bound property changed (which you missed). Just modify your code like this:

public string LogView {
  get {
    return mLogViewStr;
  }
  set {
    mLogViewStr = value;
    OnPropertyChanged(nameof(LogView))             
  }
}