如何实现使用MVVM模式的进度条 [英] How to implement a progress bar using the MVVM pattern

问题描述

我有一个建立在MVVM设计模式的WPF应用程序。

I have a WPF application which is built on the MVVM design pattern.

我想实现在应用程序的进度条，下面的MVVM模式。

I wish to implement a progress bar in the app, that follows the MVVM pattern.

没有任何一个有关于如何实现这个有什么建议？

Does any one have any suggestions on how to implement this?

在此先感谢

推荐答案

通常你的用户界面将简单地绑定到你的虚拟机属性：

Typically your UI would simply bind to properties in your VM:

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

您将虚拟机使用 的BackgroundWorker 做在后台线程的工作，并定期更新 CurrentProgress 值。事情是这样的：

Your VM would use a BackgroundWorker to do the work on a background thread, and to periodically update the CurrentProgress value. Something like this:

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;
    }
}

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