1

我需要将 a 添加UIElement到两个不同的画布，但一个UIElement只能是 ONE 画布的子级，因此我必须创建UIElement.

我想使用MemberwiseClone，但它受到保护，我不能使用它。

我也想定义一个扩展方法UIElement.ShallowCopy，但它仍然调用MemberwiseClone，它再次受到保护。

编辑：

尝试了以下所有方法，但在 Silverlight 环境中均失败：

    // System.Runtime.Serialization.InvalidDataContractException was unhandled by user code
    // Message=Type 'System.Windows.UIElement' cannot be serialized. Consider marking it with the DataContractAttribute attribute, and marking all of its members you want serialized with the DataMemberAttribute attribute. Alternatively, you can ensure that the type is public and has a parameterless constructor - all public members of the type will then be serialized, and no attributes will be required.
    public static T CloneEx<T>(this T obj) where T : class
    {
        T clone;
        DataContractSerializer dcs = new DataContractSerializer(typeof(T));

        using (MemoryStream ms = new MemoryStream())
        {
            dcs.WriteObject(ms, obj);
            ms.Position = 0;
            clone = (T)dcs.ReadObject(ms);
        }

        return clone;
    }

    // This one also throws Access/Invoke exceptions
    private readonly static object _lock = new object();
    public static T MemberwiseCloneEx<T>(this T obj) where T : class
    {
        if (obj == null)
            return null;

        try
        {
            Monitor.Enter(_lock);

            T clone = (T)Activator.CreateInstance(obj.GetType());

            PropertyInfo[] fields = obj.GetType().GetProperties(BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
            foreach (PropertyInfo field in fields)
            {
                object val = field.GetValue(obj, null);
                field.SetValue(clone, val, null);
            }

            return clone;
        }
        finally
        {
            Monitor.Exit(_lock);
        }
    }

    // System.MethodAccessException was unhandled by user code
    // Message=Attempt by method 'ToonController.ControllerUtils.MemberwiseCloneEx<System.__Canon>(System.__Canon)' to access method 'System.Object.MemberwiseClone()' failed.
    public static T MemberwiseCloneEx<T>(this T obj) where T : class
    {
        if (obj == null)
            return null;

        MethodInfo mi = obj.GetType().GetMethod("MemberwiseClone", BindingFlags.Instance | BindingFlags.NonPublic);

        if (mi == null)
            return null;

        return (T)mi.Invoke(obj, null);
    }
4

1 回答 1

1

如果您想在多个 ui 元素中使用某些东西，请“同步它们”，那么您应该创建一个 ViewModel 或类似的东西。此视图模型将设置为您要使用的任何元素的数据上下文。那么你的浅层引用很简单，你可以创建两个独立的 UI 元素绑定到相同的数据。

于 2013-02-23T23:30:18.940 回答