初始化集合项依赖属性

       在wpf自定义属性时，若此属性为集合类型的话,如下

public class DemoControl : Control
{  
    public List<string> Items
    {
        get { return (List<string>)GetValue(ItemsProperty); }
        
    }
    // Using a DependencyProperty as the backing store for Items.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty ItemsProperty =
        DependencyProperty.Register("Items", typeof(List<string>), typeof(DemoControl), new UIPropertyMetadata(new List<string>()));

}

 

使用情况

<local:DemoControl x:Name="demoControl1">
    <local:DemoControl.Items>
        <sys:String>string1</sys:String>
    </local:DemoControl.Items>
</local:DemoControl>
<local:DemoControl>
    <local:DemoControl.Items>
        <sys:String>string2</sys:String>
    </local:DemoControl.Items>
</local:DemoControl>

 

实际运行,Items属性的Count是2而不是1,这是因为其默认与所有实例共享.只需要在构造函数里初始化就可以了,设置为唯一的实例.

public DemoControl():base()
{
    SetValue(ItemsProperty, new List<string>()); 
}

msdn上有更详细的解释.