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MVVM パターンを使用して AvalonEdit を動作させようとしていますが、正確に何をすればよいかわかりません。ビジネス ロジックを実行するときにこれら 2 つの値にアクセスできるように、SelectionLength と SelectionStart を ViewModel にバインドします。

私はそのような DependencyProperties を作成し始めました:

public class MvvmTextEditor : TextEditor, INotifyPropertyChanged
{
    /// <summary>
    /// A bindable Text property
    /// </summary>
    public new string Text
    {
        get { return base.Text; }
        set { 
            base.Text = value; 
            RaisePropertyChanged();
        }
    }

    /// <summary>
    /// A bindable SelectionStart property
    /// </summary>
    public new int SelectionStart
    {
        get { return base.SelectionStart; }
        set {base.SelectionStart = value; }
    }

    /// <summary>
    /// A bindable SelectionLength property
    /// </summary>
    public new int SelectionLength
    {
        get { return base.SelectionLength; }
        set { base.SelectionLength = value; }
    }

    /// <summary>
    /// The bindable selection start property dependency property
    /// </summary>
    public static readonly DependencyProperty SelectionStartProperty =
        DependencyProperty.Register("SelectionStart", typeof(int), typeof(MvvmTextEditor),
            new PropertyMetadata((o, args) =>
            {
                var target = (TextEditor)o;
                target.SelectionStart = (int)args.NewValue;
            }));

    /// <summary>
    /// The bindable selection length property dependency property
    /// </summary>
    public static readonly DependencyProperty SelectionLengthProperty =
        DependencyProperty.Register("SelectionLength", typeof(int), typeof(MvvmTextEditor),
            new PropertyMetadata((o, args) =>
            {
                var target = (MvvmTextEditor) o;

                target.SelectionLength = (int)args.NewValue;
                Debug.WriteLine(target.SelectionLength);

            }));

    /// <summary>
    /// The bindable text property dependency property
    /// </summary>
    public static readonly DependencyProperty TextProperty =
        DependencyProperty.Register("Text", typeof(string), typeof(MvvmTextEditor),
            new PropertyMetadata((o, args) =>
            {
                var target = (MvvmTextEditor)o;
                target.Text = (string)args.NewValue;
            }));

    /// <summary>
    /// Raises a property changed event
    /// </summary>
    /// <param name="property">The name of the property that updates</param>
    public void RaisePropertyChanged([CallerMemberName] string caller = "")
    {
        var handler = PropertyChanged;
        if (handler != null)
            PropertyChanged(this, new PropertyChangedEventArgs(caller));
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

TextDependencyProperty は正常に機能していますが、SelectionLength と SelectionStart は機能していません。

SelectionChanged のイベント ハンドラーを追加しました (ただし、ここで SetValue を使用して何をしているのか正確にはわかりません。

    public MvvmTextEditor()
    {
        TextArea.SelectionChanged += TextArea_SelectionChanged;
    }

    void TextArea_SelectionChanged(object sender, EventArgs e)
    {
        SetValue(SelectionStartProperty, SelectionStart);
        SetValue(SelectionLengthProperty, SelectionLength);
    }

現在、選択は機能していますが、後方への選択には問題があります。この場合、SelectionStart は常に 0 です。これまでの作業がすべて正しければ、誰かが逆方向に選択した場合にインデックスと長さを正しく変換するロジックを作成します。このロジックを PropertyMetaDataDelegate に実装する必要はありますか?

4

1 に答える 1

3

そうそう、調べてみたらその理由がハッキリしました。両方の DP をサポートするプロパティのセッターで設定していSelectionStartましたが、これによりこれらの値の循環更新が作成され、基本クラスからのこれらの値の正しい更新が妨げられていました。更新された MVVM TextEditor クラスは以下のとおりです。SelectionEndbase.SelectionStartbase.SelectionLength

/// <summary>
/// Class that inherits from the AvalonEdit TextEditor control to 
/// enable MVVM interaction. 
/// </summary>
public class MvvmTextEditor : TextEditor, INotifyPropertyChanged
{
    /// <summary>
    /// Default constructor to set up event handlers.
    /// </summary>
    public MvvmTextEditor()
    {
        TextArea.SelectionChanged += TextArea_SelectionChanged;
    }

    /// <summary>
    /// Event handler to update properties based upon the selection changed event.
    /// </summary>
    void TextArea_SelectionChanged(object sender, EventArgs e)
    {
        this.SelectionStart = SelectionStart;
        this.SelectionLength = SelectionLength;
    }

    #region Text.
    /// <summary>
    /// Dependancy property for the editor text property binding.
    /// </summary>
    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;
         }));

    /// <summary>
    /// Provide access to the Text.
    /// </summary>
    public new string Text
    {
        get { return base.Text; }
        set { base.Text = value; }
    }

    /// <summary>
    /// Return the current text length.
    /// </summary>
    public int Length
    {
        get { return base.Text.Length; }
    }

    /// <summary>
    /// Override of OnTextChanged event.
    /// </summary>
    protected override void OnTextChanged(EventArgs e)
    {
        RaisePropertyChanged("Length");
        base.OnTextChanged(e);
    }
    #endregion // Text.

    #region Caret Offset.
    /// <summary>
    /// DependencyProperty for the TextEditorCaretOffset binding. 
    /// </summary>
    public static DependencyProperty CaretOffsetProperty =
        DependencyProperty.Register("CaretOffset", typeof(int), typeof(MvvmTextEditor),
        new PropertyMetadata((obj, args) =>
        {
            MvvmTextEditor target = (MvvmTextEditor)obj;
            target.CaretOffset = (int)args.NewValue;
        }));

    /// <summary>
    /// Provide access to the CaretOffset.
    /// </summary>
    public new int CaretOffset
    {
        get { return base.CaretOffset; }
        set { base.CaretOffset = value; }
    }
    #endregion // Caret Offset.

    #region Selection.
    /// <summary>
    /// DependencyProperty for the TextEditor SelectionLength property. 
    /// </summary>
    public static readonly DependencyProperty SelectionLengthProperty =
         DependencyProperty.Register("SelectionLength", typeof(int), typeof(MvvmTextEditor),
         new PropertyMetadata((obj, args) =>
             {
                 MvvmTextEditor target = (MvvmTextEditor)obj;
                 target.SelectionLength = (int)args.NewValue;
             }));

    /// <summary>
    /// Access to the SelectionLength property.
    /// </summary>
    public new int SelectionLength
    {
        get { return base.SelectionLength; }
        set { SetValue(SelectionLengthProperty, value); }
    }

    /// <summary>
    /// DependencyProperty for the TextEditor SelectionStart property. 
    /// </summary>
    public static readonly DependencyProperty SelectionStartProperty =
         DependencyProperty.Register("SelectionStart", typeof(int), typeof(MvvmTextEditor),
         new PropertyMetadata((obj, args) =>
             {
                 MvvmTextEditor target = (MvvmTextEditor)obj;
                 target.SelectionStart = (int)args.NewValue;
             }));

    /// <summary>
    /// Access to the SelectionStart property.
    /// </summary>
    public new int SelectionStart
    {
        get { return base.SelectionStart; }
        set { SetValue(SelectionStartProperty, value); }
    }
    #endregion // Selection.

    /// <summary>
    /// Implement the INotifyPropertyChanged event handler.
    /// </summary>
    public event PropertyChangedEventHandler PropertyChanged;
    public void RaisePropertyChanged([CallerMemberName] string caller = null)
    {
        var handler = PropertyChanged;
        if (handler != null)
            PropertyChanged(this, new PropertyChangedEventArgs(caller));
    }
}

これが他の誰かに役立つことを願っています。

于 2014-05-21T13:58:57.197 に答える