/// <summary>
/// 获取Mapping依赖属性值，若为null，则初始化为空集合
/// </summary>
/// <param name="obj">附加对象</param>
/// <returns>返回Mapping依赖属性值</returns>
internal static CommandEventCollection InternalGetMappingCollection(DependencyObject obj)
{
var map = obj.GetValue(MappingsProperty) as CommandEventCollection;
if (map == null)//属性值为null，初始化新集合
{
map = new CommandEventCollection();
SetMappings(obj, map);
}
return(map);
}
/// <summary>
/// Mapping附加依赖属性值变更处理函数
/// </summary>
/// <param name="target">附加对象</param>
/// <param name="e">信息参数</param>
private static void OnMappingsChanged(DependencyObject target, DependencyPropertyChangedEventArgs e)
{
if (e.OldValue != null)
{
CommandEventCollection cec = e.OldValue as CommandEventCollection;
if (cec != null)//解除命令与事件链接
{
cec.Unsubscribe(target);
}
}
if (e.NewValue != null)
{
CommandEventCollection cec = e.NewValue as CommandEventCollection;
if (cec != null)//进行命令与事件链接
{
cec.Subscribe(target);
}
}
}
/// <summary>
/// Mappings附加依赖属性设置方法
/// </summary>
/// <param name="obj">附加对象</param>
/// <param name="value">设置值</param>
public static void SetMappings(DependencyObject obj, CommandEventCollection value)
{
obj.SetValue(MappingsProperty, value);
}