Backgroundworker 不单独更新进度条 window

Question

我让它在不确定模式下工作，但想显示实际进度。

当我尝试从 BackgroundWorker 中更新时，出现错误“调用线程无法访问此 object，因为另一个线程拥有它。” 但是，我看到的示例似乎正在做我想做的事情。 大多数教程在主 window 中使用进度条，我想要一个单独的 window 在操作发生时出现。 这是.Net 4

进度条 Window

<Window x:Class="WpfTest.ProgressBarPopup"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="ProgressBarPopup" Height="100" Width="300">
    <Grid Margin="20">
        <ProgressBar Minimum="0" Maximum="100" Height="20" x:Name="UpdateProgress" Value="10" IsIndeterminate="False" />
        <!-- {Binding Path=PercentDone}-->
    </Grid>
</Window>

代码背后：

namespace WpfTest
{
    /// <summary>
    /// Interaction logic for ProgressBarPopup.xaml
    /// </summary>
    public partial class ProgressBarPopup : Window
    {
        public ProgressBarPopup()
        {
            InitializeComponent();
            UpdateProgress.Value = 60;
        }
    }
}

Main window：（我删除了一些关于 ObservableCollection 的内容以整理代码。）

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.ComponentModel; // for background task
using System.Threading;    // for thread.sleep

namespace WpfTest
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {    
        ProgressBarPopup bar = new ProgressBarPopup();

        bool barExists = true;

        public MainWindow()
        {
            InitializeComponent();    
        }

        private void Progress_Click(object sender, RoutedEventArgs e)
        {
            if (!barExists)
            {
                bar = new ProgressBarPopup();
                barExists = false;
            }

            bar.Show();
#if true
            BackgroundWorker worker = new BackgroundWorker();
            worker.DoWork += new DoWorkEventHandler(worker_DoWork);
            worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunCompleted);

            worker.RunWorkerAsync();
#else       
            // this simple method of doing work in foreground doesn't work with progress bars
            for (int i = 0; i < 50; i++)
            {
                Thread.Sleep(100);
            }
            bar.Hide();
            bar.Close();  // need to clean up
#endif
        }

        void worker_DoWork(object sender, DoWorkEventArgs e)
        {
            BackgroundWorker worker = sender as BackgroundWorker;
            for (int i = 0; i < 50; i++)
            {
                bar.UpdateProgress.Value = i*2;       //  <<<=== gives Error here 
                Thread.Sleep(100);
            }
        }

        void worker_RunCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            bar.Hide();
            bar.Close();
            barExists = false;
        }
    }
}

Answer 1

您无法从DoWork()方法访问UI线程，因为该方法中的代码在单独的线程上运行。 您必须为此使用BackgroundWorker.ProgressChanged事件和BackgroundWorker.ReportProgress方法。

Answer 2

您将必须像这样调用控件。 表单控件在自己的线程上运行。 由于后台工作程序是单独运行的，因此它没有足够的特权来访问该控件。 请查看MethodInvoker，以将您的控件与后台工作人员分开。

void worker_RunCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
           _RunCompleted();
        }


private void _RunCompleted(){
MethodInvoker action = delegate
            {
           bar.Hide();
            bar.Close();
            barExists = false;
};
}

Answer 3

只有后台工作程序的 Progress Changed 是线程安全的，因此您应该从进度更改对 UI 进行任何更改，但不仅限于 UI。

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.ComponentModel; // for background task
using System.Threading;    // for thread.sleep

namespace WpfTest
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {    
        ProgressBarPopup bar = new ProgressBarPopup();

        bool barExists = true;

        public MainWindow()
        {
            InitializeComponent();    
        }

        private void Progress_Click(object sender, RoutedEventArgs e)
        {
            if (!barExists)
            {
                bar = new ProgressBarPopup();
                barExists = false;
            }

            bar.Show();
#if true
            BackgroundWorker worker = new BackgroundWorker();
            worker.DoWork += new DoWorkEventHandler(worker_DoWork);
            worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunCompleted);

            worker.RunWorkerAsync();
#else       
            // this simple method of doing work in foreground doesn't work with progress bars
            for (int i = 0; i < 50; i++)
            {
                Thread.Sleep(100);
            }
            bar.Hide();
            bar.Close();  // need to clean up
#endif
        }

        void worker_DoWork(object sender, DoWorkEventArgs e)
        {
            BackgroundWorker worker = sender as BackgroundWorker;
            for (int i = 0; i < 50; i++)
            {
                worker.reportprogress(i)
                Thread.Sleep(100);
            }
        }

       void worker_ProgressChanged(object sender, DoWorkEventArgs e)

{
    int i=e.progresschanged
     bar.UpdateProgress.Value = i*2;       //  <<<=== gives Error here 
}

        void worker_RunCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            bar.Hide();
            bar.Close();
            barExists = false;
        }
    }
}