[UWP]以编程方式在UWP ListView中移动项目而不刷新 [英] [UWP]programmatically move items in UWP ListView without refresh

问题描述

以下问题让我现在忙了很长一段时间，它似乎是如此基本，但它只是不起作用。归结为：

The following problem is keeping me busy now for quite some time, it seems to be so basic, yet it just doesn't work. It boils down to this:

• 拥有一个绑定到某个合适集合的ListView代码隐藏（ObservableCollection，ReactiveList，或类似）
  
• 我每隔x秒一次移动一个项目
• ，所有这些项目得到刷新（至少看起来像那样。一瞬间所有项目都会消失，然后重新出现在新订单中）

• Having a ListView that is bound to some suitable collection in code behind (ObservableCollection, ReactiveList, or alike)
• I'm moving items one at a time every x seconds
• on every move, all of the items get refreshed (at least it looks like that. for a split seconds all items disappear, then reappear in the new order)

必须有办法保留其他元素并且只是"移动"移动的项目。像拖放重新排序，但从后面的代码。我甚至不关心移动项目的花哨翻译动画，我只想让其他元素
留在屏幕上。当然，我的真实用例不是随机移动项目，而是在后面的代码中对列表进行排序。但我将问题追溯到这个简单的案例。

there must be a way to keep the other element and just "move" the moved item. Like the drag&drop reordering, but from the code behind. I even don't care about a fancy translation animation for the moved item, I just want the other elements to stay on screen. of course my real usecase is not moving items randomly but sorting the list in code behind. But I tracked the issue down to this simple case.

有一个简单的ListView并让它绑定例如到CodeBehind中的ObservableCollection，下面是我的虚拟代码来移动项目。没什么特别的，一切都归结为：每1秒将一个随机项目移动到索引5：

having a simple ListView and having it bound e.g. to a ObservableCollection in CodeBehind, the following is my dummy code to move around the items. Nothing special at all, it all boils down to: Move a random item to index 5 every 1 seconds:

_timer = new Timer(async _ =>
{
    Random r = new Random();
    var randomIndex = r.Next(0, contactsCvsSource.Count - 1);

    await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () => { contactsCvsSource.Move(randomIndex, 5); });
}
, null, 0, 1000);

推荐答案

你好，

ObservableCollection.Move调用RemoveItem的ObservableCollection实现，它导致刷新所有项目，而不是使用Collection< T>方法RemoveAt和Insert

ObservableCollection.Move call ObservableCollection implementation of RemoveItem which is cause to refresh all items, instead use Collection<T> methods RemoveAt and Insert

                        var s = contactsCvsSource[randomIndex];
                        contactsCvsSource.RemoveAt(randomIndex);
                        contactsCvsSource.Insert(5, s);

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