是否需自行编写OnPropertyChanged及BooleanToVisibilityConverter代码？

Great questions—these are super common when you're getting up to speed with XAML-based frameworks like WPF! Let's tackle each one clearly:

Do I need to write the OnPropertyChanged boilerplate code myself? #

Short answer: It depends on whether you're using a MVVM framework or not.

• If you're using a modern MVVM library (like Microsoft's MVVM Toolkit, Prism, or MvvmLight), you don't need to write that repetitive handler code. These frameworks provide base classes (e.g., ObservableObject in MVVM Toolkit) that encapsulate the INotifyPropertyChanged implementation. For example, with MVVM Toolkit, you can just do:

  using CommunityToolkit.Mvvm.ComponentModel;
  
  public class MyViewModel : ObservableObject
  {
      private string _myProperty;
      public string MyProperty
      {
          get => _myProperty;
          set => SetProperty(ref _myProperty, value); // This triggers PropertyChanged automatically
      }
  }
  

  The SetProperty method handles checking if the value changed, updating the backing field, and raising the PropertyChanged event—no need for manual handler checks.

• If you're not using a framework, you should still avoid writing that boilerplate every time. Instead, create a reusable base class that implements INotifyPropertyChanged once, then have all your view models inherit from it. Here's a minimal example:

  using System.ComponentModel;
  using System.Runtime.CompilerServices;
  
  public class BaseViewModel : INotifyPropertyChanged
  {
      public event PropertyChangedEventHandler PropertyChanged;
  
      protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
      {
          // Using the null-conditional operator to simplify the check
          PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
      }
  
      // Optional: Add a helper to set properties and trigger the event
      protected bool SetProperty<T>(ref T backingField, T value, [CallerMemberName] string propertyName = null)
      {
          if (EqualityComparer<T>.Default.Equals(backingField, value))
              return false;
  
          backingField = value;
          OnPropertyChanged(propertyName);
          return true;
      }
  }
  

  Now your view models can just call OnPropertyChanged() or SetProperty() without rewriting the event logic.

Do I need to implement my own BooleanToVisibilityConverter? #

Short answer: No, not for basic use—WPF has a built-in one!

The .NET Framework (and .NET Core/.NET 5+) includes a BooleanToVisibilityConverter in the System.Windows.Controls namespace. You can use it directly in your XAML without writing any custom code:

1. First, add it as a resource (usually in your Window/UserControl resources):

   <Window.Resources>
       <BooleanToVisibilityConverter x:Key="BoolToVisConverter" />
   </Window.Resources>
   

2. Then reference it in your binding:

   <Button Content="Click Me" Visibility="{Binding IsButtonVisible, Converter={StaticResource BoolToVisConverter}}" />
   

   This will convert true to Visibility.Visible and false to Visibility.Collapsed (by default).

You only need to write a custom converter if you need special behavior, like:

• Inverting the logic (e.g., true = Collapsed, false = Visible)
• Handling null values differently
• Using Hidden instead of Collapsed for false values

Here's an example of a custom inverted converter if you need that:

using System;
using System.Globalization;
using System.Windows;
using System.Windows.Data;

public class InvertedBoolToVisibilityConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is bool isVisible)
        {
            return isVisible ? Visibility.Collapsed : Visibility.Visible;
        }
        // Fallback if the value isn't a boolean
        return Visibility.Collapsed;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is Visibility visibility)
        {
            return visibility != Visibility.Visible;
        }
        return false;
    }
}

内容的提问来源于stack exchange，提问作者Black Panther