c# - 使用 MVVM 绑定(bind)到 AvalonEdit 文档文本的两种方式

Question

我想将 AvalonEdit TextEditor 控件包含到我的 MVVM 应用程序中。我需要的第一件事是能够绑定(bind)到 TextEditor.Text 属性，以便我可以显示文本。为此，我遵循了 Making AvalonEdit MVVM compatible 中给出的示例。 .现在，我已经使用接受的答案作为模板实现了以下类

public sealed class MvvmTextEditor : TextEditor, INotifyPropertyChanged
{
    public static readonly DependencyProperty TextProperty =
         DependencyProperty.Register("Text", typeof(string), typeof(MvvmTextEditor),
         new PropertyMetadata((obj, args) =>
             {
                 MvvmTextEditor target = (MvvmTextEditor)obj;
                 target.Text = (string)args.NewValue;
             })
        );

    public new string Text
    {
        get { return base.Text; }
        set { base.Text = value; }
    }

    protected override void OnTextChanged(EventArgs e)
    {
        RaisePropertyChanged("Text");
        base.OnTextChanged(e);
    }

    public event PropertyChangedEventHandler PropertyChanged;
    public void RaisePropertyChanged(string info)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(info));
    }
}

XAML 在哪里

<Controls:MvvmTextEditor HorizontalAlignment="Stretch"
                         VerticalAlignment="Stretch"
                         FontFamily="Consolas"
                         FontSize="9pt" 
                         Margin="2,2" 
                         Text="{Binding Text, NotifyOnSourceUpdated=True, Mode=TwoWay}"/>

首先，这是行不通的。 Binding 根本没有显示在 Snoop 中(不是红色，什么都没有，事实上我什至看不到 Text 依赖属性)。

我看到这个问题和我的一模一样Two-way binding in AvalonEdit doesn't work但接受的答案不 有效(至少对我而言)。所以我的问题是:

如何使用上述方法执行双向绑定(bind)以及我的 MvvmTextEditor 类的正确实现是什么？

感谢您的宝贵时间。

---

注意:我的 ViewModel 中有我的 Text 属性，它实现了所需的 INotifyPropertyChanged 接口(interface)。

Answer 1

创建一个将附加 TextChanged 事件的行为类，并将连接绑定(bind)到 ViewModel 的依赖属性。

AvalonTextBehavior.cs

public sealed class AvalonEditBehaviour : Behavior<TextEditor> 
{
    public static readonly DependencyProperty GiveMeTheTextProperty =
        DependencyProperty.Register("GiveMeTheText", typeof(string), typeof(AvalonEditBehaviour), 
        new FrameworkPropertyMetadata(default(string), FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, PropertyChangedCallback));

    public string GiveMeTheText
    {
        get { return (string)GetValue(GiveMeTheTextProperty); }
        set { SetValue(GiveMeTheTextProperty, value); }
    }

    protected override void OnAttached()
    {
        base.OnAttached();
        if (AssociatedObject != null)
            AssociatedObject.TextChanged += AssociatedObjectOnTextChanged;
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();
        if (AssociatedObject != null)
            AssociatedObject.TextChanged -= AssociatedObjectOnTextChanged;
    }

    private void AssociatedObjectOnTextChanged(object sender, EventArgs eventArgs)
    {
        var textEditor = sender as TextEditor;
        if (textEditor != null)
        {
            if (textEditor.Document != null)
                GiveMeTheText = textEditor.Document.Text;
        }
    }

    private static void PropertyChangedCallback(
        DependencyObject dependencyObject,
        DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
    {
        var behavior = dependencyObject as AvalonEditBehaviour;
        if (behavior.AssociatedObject!= null)
        {
            var editor = behavior.AssociatedObject as TextEditor;
            if (editor.Document != null)
            {
                var caretOffset = editor.CaretOffset;
                editor.Document.Text = dependencyPropertyChangedEventArgs.NewValue.ToString();
                editor.CaretOffset = caretOffset;
            }
        }
    }
}

View.xaml

 <avalonedit:TextEditor
        WordWrap="True"
        ShowLineNumbers="True"
        LineNumbersForeground="Magenta"
        x:Name="textEditor"
        FontFamily="Consolas"
        SyntaxHighlighting="XML"
        FontSize="10pt">
        <i:Interaction.Behaviors>
            <controls:AvalonEditBehaviour GiveMeTheText="{Binding Test, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
        </i:Interaction.Behaviors>
    </avalonedit:TextEditor>

i 必须定义为

xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"

ViewModel.cs

    private string _test;
    public string Test
    {
        get { return _test; }
        set { _test = value; }
    }

这应该会为您提供文本并将其推送回 ViewModel。