自定义控件写只读属性并绑定

控件依赖属性:

#region SelectionText

internal static readonly DependencyPropertyKey SelectionTextPropertyKey = DependencyProperty.RegisterReadOnly(
	"SelectionText", typeof(string),
	typeof(QuJiaoRichTextBox), new PropertyMetadata(string.Empty)
);

public static readonly DependencyProperty SelectionTextProperty = SelectionTextPropertyKey.DependencyProperty;

/// <summary>
/// 当前选择文本(外部只读)
/// </summary>
public string SelectionText
{
	get => (string)GetValue(SelectionTextPropertyKey.DependencyProperty);
	internal set => SetValue(SelectionTextPropertyKey, value);
}

#endregion

xaml调用时绑定:

SelectionText="{Binding Path=模型的绑定属性名称,ElementName=SelectionText}"