我正在尝试使用 MVVM 模式让 AvalonEdit 正常工作,但我真的不知道该怎么做。我想将 SelectionLength 和 SelectionStart 绑定到我的 ViewModel,以便在执行某些业务逻辑时可以访问这两个值。
我开始像这样创建 DependencyProperties:
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 工作正常,但 SelectionLength 和 SelectionStart 不工作。
我为 SelectionChanged 添加了一个事件处理程序(但我并不完全使用 SetValue 在这里做的事情:
public MvvmTextEditor()
{
TextArea.SelectionChanged += TextArea_SelectionChanged;
}
void TextArea_SelectionChanged(object sender, EventArgs e)
{
SetValue(SelectionStartProperty, SelectionStart);
SetValue(SelectionLengthProperty, SelectionLength);
}
选择现在可以工作,但是向后选择有问题。在这种情况下,SelectionStart 始终为 0。如果到目前为止我所做的一切都是正确的,那么我将创建一个逻辑,如果有人向后选择,则将索引和长度正确转换。我必须在 PropertyMetaDataDelegate 中实现这个逻辑吗?