c# - 如何使用 MVVM 模式实现进度条

Question

我有一个基于 MVVM 设计模式构建的 WPF 应用程序。

我希望在应用中实现一个进度条，它遵循 MVVM 模式。

有人对如何实现这一点有什么建议吗？

提前致谢

Answer 1

通常，您的 UI 会简单地绑定(bind)到 VM 中的属性:

<ProgressBar Value="{Binding CurrentProgress, Mode=OneWay}" 
             Visibility="{Binding ProgressVisibility}"/>

您的 VM 将使用 BackgroundWorker在后台线程上完成工作，并定期更新 CurrentProgress 值。像这样:

public class MyViewModel : ViewModel
{
    private readonly BackgroundWorker worker;
    private readonly ICommand instigateWorkCommand;
    private int currentProgress;

    public MyViewModel()
    {
        this.instigateWorkCommand = 
                new DelegateCommand(o => this.worker.RunWorkerAsync(), 
                                    o => !this.worker.IsBusy);

        this.worker = new BackgroundWorker();
        this.worker.DoWork += this.DoWork;
        this.worker.ProgressChanged += this.ProgressChanged;
    }

    // your UI binds to this command in order to kick off the work
    public ICommand InstigateWorkCommand
    {
        get { return this.instigateWorkCommand; }
    }

    public int CurrentProgress
    {
        get { return this.currentProgress; }
        private set
        {
            if (this.currentProgress != value)
            {
                this.currentProgress = value;
                this.OnPropertyChanged(() => this.CurrentProgress);
            }
        }
    }

    private void DoWork(object sender, DoWorkEventArgs e)
    {
        // do time-consuming work here, calling ReportProgress as and when you can
    }

    private void ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
        this.CurrentProgress = e.ProgressPercentage;
    }
}