How to Hook a Progress Bar to IO.Stream

You can integrate a progressbar when uploading files in C++ applications.

A progress bar to IO stream indicates the progress of uploading or downloading files. An IO stream handles input and output functionality using streams. A stream is an abstraction which represents a device where input and output are conducted. Streams are related to a physical source like keyboard or an input console. C++ provides the standard iostream library including basic class templates, types and manipulators.

Instructions

1. Click “Start,” “All Programs” and “Visual Studio” to enter the Integrated Development Environment. Select programming language as Visual C++. Click “Form1.cs” to switch to the design view. Click “Toolbox” and “Button” to create a new Button named "button1."

2. Double-click the button1 and enter the following code to obtain information about input file:

   using System;
   using System.IO
   System.IO.FileInfo fileInfo = new System.IO.FileInfo(FileTextBox.Text);

3. Read from file "c:\\text1.txt" into the new FileStream variable "stream" using the following code:

   using (System.IO.FileStream stream = new System.IO.FileStream("c:\\text1.txt", System.IO.FileMode.Open, System.IO.FileAccess.Read))

   The use of the ProgressChanged event reports the progress of upload. Obtain the upload progress using vairable "uploadStreamWithProgress."

   { using (StreamWithProgress uploadStreamWithProgress = new StreamWithProgress(stream))
   { uploadStreamWithProgress.ProgressChanged += uploadStreamWithProgress_ProgressChanged;

4. Double-click form1. Get the file upload progress via the following functions.

   Define variable bytesRead: private long bytesRead;

   Read the loaded bytes into variable "bytesRead" in function StreamWithProgress to

   public StreamWithProgress(FileStream file)
   {
   this.file = file;
   length = file.Length;
   bytesRead = 0;
   if (ProgressChanged != null) ProgressChanged(this, new ProgressChangedEventArgs(bytesRead, length));
   }

   Calculate and return the progress of uploading in the GetProgress function:
   public double GetProgress()
   {
   return ((double)bytesRead) / file.Length;
   }

References

• Cplusplus.com: IOstream Library