用户界面仍然使用backgroundWorker冻结 [英] UI still freezes using backgroundWorker

问题描述

我对WPF很陌生.我正在开发PRISM应用程序，并希望在更新枚举时更新UI. 我在modelView中使用backgroundWorker来更新枚举.一切正常，直到它自身的枚举被更新，然后UI冻结！ 一位朋友告诉我，我也许可以使用yield关键字，但我不太清楚.

I'm quite new to WPF. I am developing a PRISM application and want to update the UI when an enumerable is updated. I use a backgroundWorker in my modelView to update the enumaration. it all works fine until the enumeration it self gets updated and then the UI freezes!! a friend told my I might be able to use the yield keyword but I didn't quite figured it out.

这是代码:

public void ChangeCollection()
    {
        BackgroundWorker worker = new BackgroundWorker();

        // Set workers job
        worker.DoWork += (sender, e) =>
            {
                RunOnUIThread(() => IsBusy = true);
                e.Result = GetPrimes();
            };

        // On Complete
        worker.RunWorkerCompleted += (sender, e) =>
            {
                RunOnUIThread(() =>
                    {
                        IsBusy = false;

                        // HERE IS WHERE IT GETS STUCK
                        Numbers = new ObservableCollection<int>
                            ((IEnumerable<int>)e.Result);
                    });
            };

        // Start background operation
        worker.RunWorkerAsync();
    } 

    public ObservableCollection<int> Numbers 
    { 
        get {return _Numbers;} 
        set
        {
            _Numbers = value;
            RaisePropertyChanged(() => Numbers);
        }
    }

    public IEnumerable<int> GetPrimes()
    {
        List<int> primes = new List<int>();

        for (int i = 0; i < 100000; i++)
        {
            bool IsPrime = true;

            for (int j = 2; j < i; j++)
            {
                if (i % j == 0)
                    IsPrime = false;
            }

            if (IsPrime)
                primes.Add(i);
        }

        return primes;
    } 

任何建议都将得到极大的应用！

Any advise would be greatly appriciated!

谢谢， 欧姆里

推荐答案

这里有几件事. 1)实例化包含它的对象时，应创建您的工作程序及其委托.

A few things here. 1) Your worker and its delegates should be created when your object containing it is instantiated.

public class ViewModel 
{
    BackgroundWorker _primeWorker;

    public ViewModel()
    {
        _primeWorker = new BackgroundWorker;

        _primeWorker.DoWork += ...
    }

    public void AddSomeNumbers()
    {
         if(_primerWorker.IsBusy == false)
              _primeWorker.RunWorkerAsync();
    }
}

2)当实例化包含它的对象时，应该实例化您的集合，以避免使用该类的对象调用get时引发空异常.

2) Your collection should be instantiated when the object containing it is instantiated to avoid a null exception being thrown should the object using this class calls the get.

3)由于每次添加一个数字，添加许多项会导致速度变慢.会触发UI线程必须处理的事件.

3) Adding that many items would cause slowness due to each time you add a number an event is fired that the UI thread has to handle.

此链接提供了更多信息来帮助您. http://msdn.microsoft.com/en -us/library/cc221403(v = vs.95).aspx

This link has more info to help you out. http://msdn.microsoft.com/en-us/library/cc221403(v=vs.95).aspx

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