实施上的AddRange用的ObservableCollection数据绑定适当的支持 [英] Implement AddRange on ObservableCollection with proper support for DataBinding

问题描述

我想我自己的的ObservableCollection 的后裔，以支持的AddRange 方法。
这是我目前有：

I would like my own descendant of ObservableCollection to support AddRange method. Here is what I currently have:

public class ObservableCollectionPlus<T> : ObservableCollection<T>
{
    public void InsertRange(IEnumerable<T> items)
    {
        this.CheckReentrancy();
        foreach (var item in items) Items.Add(item);

        var type = NotifyCollectionChangedAction.Reset;
        var colChanged = new NotifyCollectionChangedEventArgs(type);
        var countChanged = new PropertyChangedEventArgs("Count");

        OnPropertyChanged(countChanged);
        OnCollectionChanged(colChanged);
    }
}

我没有什么也正是要多少知识在这里，为什么这些事件引起人们的关注。这是在做对谷歌和计算器一些研究之后，我已经组建了一个solutiom。

I don't have much knowledge of what's exactly going on here and why are these events get raised. This is a solutiom that I've assembled after doing some research on google and stackoverflow.

现在，如果我结合我的类的实例说 LongListSelector 然后，通过后动态添加项目 InsertRange 到 ObservableCollectionPlus ，一个绑定 LongListSelector 的滚动位置发送到它的上面。

Now, if I bind an instance of my class to say LongListSelector then, after dynamically adding items via InsertRange to ObservableCollectionPlus, a binded LongListSelector's scroll position is sent to it's top.

如果我添加项目本标准方式：的foreach（在项目VAR项目）collection.Add（项目）; 然后 LongListSelector 的地位没有得到转变。但是，当然，这样一来我得到的数据绑定通知开销是不需要的。

If I add items in this standard way: foreach (var item in items) collection.Add(item); then LongListSelector's position does not get shifted. But of course this way I get DataBinding notifications overhead in which is undesired.

显然，事情是在我目前的解决方案做了错事。我如何能实现 InsertRange 将完全一样的foreach（VAR项项目）collection.Add（项目）; 但只会火数据绑定通知一次，不会做奇怪的事情来绑定对象的滚动位置？

Apparently, something is done wrong in my current solution. How can I implement InsertRange that will behave exactly like foreach (var item in items) collection.Add(item); but will only fire DataBinding notification once and will not do strange things to binded object's scroll position?

推荐答案

这可能是因为您的发送在 NotifyCollectionChangedAction.Reset 的通知，也许只是在 NotifyCollectionChangedAction.Add 将工作，也许：）

It could be because your sending the NotifyCollectionChangedAction.Reset notification, maybe just the NotifyCollectionChangedAction.Add will work, Maybe :)

public class ObservableRangeCollection<T> : ObservableCollection<T>
{
    public void AddRange(IEnumerable<T> collection)
    {
        foreach (var i in collection)
        {
            Items.Add(i);
        }
        OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, collection.ToList()));
    }
}

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