Question

I just got into WPF and am currently trying my luck with the Background worker, so I figured I’d just open any file using the FileOpenDialog, loop through all the bytes inside the file and report the total progress via worker.ReportProgress in percentage … alas, this only works for like ~20 times and then it gets really stuck and suddenly stops at 100%.

Here’s my code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
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 Microsoft.Win32;
using System.IO;
using System.Threading;
using System.ComponentModel;

namespace BitStream
{
public partial class MainWindow : Window
{
    private int bytes = 0;
    private long length = 0;

    public MainWindow()
    {
        InitializeComponent();
    }

    private void selectFile_Click(object sender, RoutedEventArgs e)
    {
        BackgroundWorker bw = new BackgroundWorker();
        OpenFileDialog ofd = new OpenFileDialog();
        if ((bool)ofd.ShowDialog())
        {
            FileInfo fi = new FileInfo(ofd.FileName);
            this.length = fi.Length;
            bw.DoWork += bw_DoWork;
            bw.RunWorkerCompleted += bw_RunWorkerCompleted;
            bw.ProgressChanged += bw_ProgressChanged;
            bw.WorkerReportsProgress = true;
            Stream str = ofd.OpenFile();

            bw.RunWorkerAsync(str);
        }
    }

    private void bw_DoWork(object sender, DoWorkEventArgs e)
    {
        Stream str = (Stream)e.Argument;
        int singleByte = 0;
        this.Dispatcher.Invoke(
                new Action(() =>
                {
                    int currentProgress = 0;
                    while ((singleByte = str.ReadByte()) != -1)
                    {

                        label1.Content = singleByte;
                        bytes++;

                        currentProgress = Convert.ToInt32(((double)bytes) / length * 100);
                        if (currentProgress > progress)
                        {
                            progress = currentProgress;
                            ((BackgroundWorker)sender).ReportProgress(progress);
                            Thread.Sleep(100);
                        }
                    }
                }

            ), System.Windows.Threading.DispatcherPriority.Render);
    }

    private void bw_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
        label2.Content = e.ProgressPercentage + "% completed";
    }

    private void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
    }
}

}

Labels 1 and 2 are there for showing the current byte and the current progress in %.

Feel free to also criticize every other aspect of my code, I just got started with WPF today.

Edited DoWork-Method:

 private void bw_DoWork(object sender, DoWorkEventArgs e)
    {
        Stream str = (Stream)e.Argument;
        int singleByte = 0;

        int currentProgress = 0;
        while ((singleByte = str.ReadByte()) != -1)
        {
            this.Dispatcher.Invoke(
                new Action(() =>
                {
                    label1.Content = singleByte;
                }), System.Windows.Threading.DispatcherPriority.Render);
            bytes++;

            currentProgress = Convert.ToInt32(((double)bytes) / length * 100);
            if (currentProgress > progress)
            {
                progress = currentProgress;
                this.Dispatcher.Invoke(
                new Action(() =>
                {
                    ((BackgroundWorker)sender).ReportProgress(progress);


                }), System.Windows.Threading.DispatcherPriority.Render);
                Thread.Sleep(500);        
            }
        }
    }

Thanks,

Dennis

Answer 1

So assuming you really want to make a cross thread call for each byte (which I wouldn’t recommend), the code would look something like:

private void bw_DoWork(object sender, DoWorkEventArgs e) 
{ 
    Stream str = (Stream)e.Argument; 
    int singleByte = 0; 
    int currentProgress = 0; 
    while ((singleByte = str.ReadByte()) != -1) 
    { 

       bytes++; 
       this.Dispatcher.Invoke( 
            new Action(() => 
            { 
                    label1.Content = singleByte; 
            } 

        ), System.Windows.Threading.DispatcherPriority.Render); 

        currentProgress = Convert.ToInt32(((double)bytes) / length * 100); 
        if (currentProgress > progress) 
        { 
            progress = currentProgress; 
            ((BackgroundWorker)sender).ReportProgress(progress); 
            Thread.Sleep(100); 
        } 
    } 
} 

The idea being that you can only manipulate a DispatcherObject on the thread on which it was created.