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Posted 14 Apr 2009

Asynchronous stream reader with progress bar support

, 14 Apr 2009
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Asynchronous stream reader with progress bar support.


This piece of code does async stream reading enabling you to use a progress bar in your application. On every byte read, it fires an event that contains the percentage of current read progress.

This is just an idea of how to make an async reader, so if you have any suggestions on how make it better or faster, let me now.

Using the code

The following are the AsyncStreamReader events:

  • EventHandler<AsyncReadEventArgs> OnReadedBytes - Occurs when the byte is read from the System.IO.StreamReader, and contains the percentage of total read bytes.
  • EventHandler<AsyncReadEventArgs> OnEndRead - Occurs when all bytes are read from the System.IO.StreamReader and contains the byte array of the read content.
  • EventHandler<AsyncReadErrorEventArgs> OnError - Occurs when an AsyncStream.AsyncExcpetion happens and contains the exception.
  • EventHandler<AsyncStreamStateChangeArgs> OnStateChanged - Occurs when the state of AsyncStream.AsyncStreamReader changes and contains the current state.

The following are the AsyncStreamReader public properties:

  • AsyncStreamState State - Specifies the identifiers to indicate the the state of AsyncStream.AsyncStreamReader.
  • string Path - Gets the complete file path to be read.

The following are the AsyncStreamReader pubic methods:

  • BeginRead() - Begins an asynchronous read operation and sets the state to Started.
  • StopRead() - Stops an asynchronous read operation and sets the state to Stopped.
  • PauseRead() - Pauses an asynchronous read operation and sets the state to Paused.
  • ResumeRead() - Resumes a paused asynchronous read operation and sets the state back to Started.



This is how we create a new asynchronous stream:

AsyncStreamReader reader = new AsyncStreamReader(fileName);
reader.OnReadedBytes += new EventHandler<AsyncReadEventArgs>(reader_OnReadedBytes);
reader.OnEndRead += new EventHandler<AsyncReadEventArgs>(reader_OnEndRead);
reader.OnStateChanged += 
       new EventHandler<AsyncStreamStateChangeArgs>(reader_OnStateChanged);
reader.OnError += new EventHandler<AsyncReadErrorEventArgs>(reader_OnError);

Here is the OnReadedBytes event:

void reader_OnReadedBytes(object sender, AsyncReadEventArgs e)
   int percents = e.PercentReaded; // percents of readed bytes
   bool isComplete = e.IsComplete; // is read completed
   long bytesReaded = e.BytesReaded; // number of readed bytes
   long length = e.Length; // total length of bytes to read;
   byte[] bytes = e.Result; // all readed bytes


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Web Developer
Slovenia Slovenia
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Comments and Discussions

GeneralFYI - Speed Issue in AsyncReader Pin
EtherealMonkey6-Dec-10 19:41
memberEtherealMonkey6-Dec-10 19:41 
GeneralMy vote of 4 Pin
EtherealMonkey6-Dec-10 18:21
memberEtherealMonkey6-Dec-10 18:21 
QuestionTitle? Pin
Adrian Cole14-Apr-09 10:28
memberAdrian Cole14-Apr-09 10:28 
Generalworker.Abort(); Pin
Marc Leger14-Apr-09 7:17
memberMarc Leger14-Apr-09 7:17 
GeneralRe: worker.Abort(); Pin
mbostjan14-Apr-09 7:57
membermbostjan14-Apr-09 7:57 

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