我可以以某种方式暂时禁用 WPF 数据绑定更改吗? [英] Can I somehow temporarily disable WPF data binding changes?

问题描述

我有一个使用 MVVM 数据绑定的 WPF 应用程序.我正在向 ObservableCollection<...> 添加项目，而且确实有很多项目.

I have a WPF application that uses MVVM data bindings. I am adding items to an ObservableCollection<...> and quite many of them indeed.

现在我想知道每次我向集合中添加一个时，它是否会立即触发事件并导致不必要的开销?如果是这样，我能否以某种方式暂时禁用事件通知并在我的代码末尾手动触发一次，这样如果我添加 10k 项，它只会触发一次，而不是 10k 次?

Now I am wondering that every time I add one to the collection, does it instantly fire the event and cause unnecessary overhead? If so, can I somehow temporarily disable the event notifications and manually fire it once at the end of my code so that if I add 10k items, it gets only fired once, rather than 10k times?

更新:我试过这门课:

using System;
using System.Linq;
using System.Collections.Specialized;
using System.Collections.Generic;

namespace MyProject
{

    /// <summary> 
    /// Represents a dynamic data collection that provides notifications when items get added, removed, or when the whole list is refreshed. 
    /// </summary> 
    /// <typeparam name="T"></typeparam> 
    public class ObservableCollection<T> : System.Collections.ObjectModel.ObservableCollection<T>
    {

        /// <summary> 
        /// Adds the elements of the specified collection to the end of the ObservableCollection(Of T). 
        /// </summary> 
        public void AddRange(IEnumerable<T> collection)
        {
            foreach (var i in collection) Items.Add(i);
            OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, collection.ToList()));
        }

        /// <summary> 
        /// Removes the first occurence of each item in the specified collection from ObservableCollection(Of T). 
        /// </summary> 
        public void RemoveRange(IEnumerable<T> collection)
        {
            foreach (var i in collection) Items.Remove(i);
            OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, collection.ToList()));
        }

        /// <summary> 
        /// Clears the current collection and replaces it with the specified item. 
        /// </summary> 
        public void Replace(T item)
        {
            ReplaceRange(new T[] { item });
        }
        /// <summary> 
        /// Clears the current collection and replaces it with the specified collection. 
        /// </summary> 
        public void ReplaceRange(IEnumerable<T> collection)
        {
            List<T> old = new List<T>(Items);
            Items.Clear();
            foreach (var i in collection) Items.Add(i);
            OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Replace, collection.ToList()));
        }

        /// <summary> 
        /// Initializes a new instance of the System.Collections.ObjectModel.ObservableCollection(Of T) class. 
        /// </summary> 
        public ObservableCollection() : base() { }

        /// <summary> 
        /// Initializes a new instance of the System.Collections.ObjectModel.ObservableCollection(Of T) class that contains elements copied from the specified collection. 
        /// </summary> 
        /// <param name="collection">collection: The collection from which the elements are copied.</param> 
        /// <exception cref="System.ArgumentNullException">The collection parameter cannot be null.</exception> 
        public ObservableCollection(IEnumerable<T> collection) : base(collection) { }
    }
}

我现在收到此错误:

附加信息:不支持范围操作.

Additional information: Range actions are not supported.

错误出现在这里:

OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, collection.ToList()));

推荐答案

一个非常快速和简单的方法是子类化 ObservableCollection 并在调用 AddRange 时暂停通知.请参阅以下博文以进行说明.

A very quick and easy way is to subclass ObservableCollection and suspend notifications when AddRange is called. See the following blog post for clarification.

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