This example demonstrates overriding the default IO routines.

Visual Basic

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' Redirect Read event example Private myStream As FileStream ' Redirect Open event example Private Sub Codecs_Open(ByVal sender As Object, ByVal e As CodecsRedirectOpenEventArgs)    myStream = New FileStream(e.FileName, e.Mode)    e.Success = True End Sub ' Redirect Seek event example Private Sub Codecs_Seek(ByVal sender As Object, ByVal e As CodecsRedirectSeekEventArgs)    myStream.Seek(e.Offset, e.Origin) End Sub ' Redirect Read event example Private Sub Codecs_Read(ByVal sender As Object, ByVal e As CodecsRedirectReadEventArgs)    Dim byteBuffer As Byte() = New Byte(e.Count - 1) {}    myStream.Read(byteBuffer, 0, e.Count)    Marshal.Copy(byteBuffer, 0, e.Buffer, e.Count)    e.Read = e.Count    Console.WriteLine("The number of bytes that read request should copy to the buffer is : {0}", e.Count)    Console.WriteLine("The actual number of bytes that this read request has copied to Buffer is : {0}", e.Read) End Sub ' Redirect Write event example Private Sub Codecs_Write(ByVal sender As Object, ByVal e As CodecsRedirectWriteEventArgs)    Dim byteBuffer As Byte() = New Byte(e.Count - 1) {}    Marshal.Copy(e.Buffer, byteBuffer, 0, e.Count)    e.Written = e.Count    myStream.Write(byteBuffer, 0, e.Count)    Console.WriteLine("The number of bytes that write request should copy from the buffer is : {0}", e.Count)    Console.WriteLine("The actual number of bytes that this write request has copied from Buffer is : {0}", e.Written) End Sub ' Redirect Close event example Private Sub Codecs_Close(ByVal sender As Object, ByVal e As CodecsRedirectCloseEventArgs)    myStream.Close() End Sub Public Sub StartRedirectingExample()    RasterCodecs.Startup()    Dim codecs As RasterCodecs = New RasterCodecs()    AddHandler codecs.RedirectOpen, AddressOf Codecs_Open    AddHandler codecs.RedirectSeek, AddressOf Codecs_Seek    AddHandler codecs.RedirectRead, AddressOf Codecs_Read    AddHandler codecs.RedirectWrite, AddressOf Codecs_Write    AddHandler codecs.RedirectClose, AddressOf Codecs_Close    Dim srcFilename As String = LeadtoolsExamples.Common.ImagesPath.Path + "Image1.cmp"    codecs.StartRedirecting()    Dim image As RasterImage = codecs.Load(srcFilename)    myStream.Close()    codecs.Save(image, LeadtoolsExamples.Common.ImagesPath.Path + "Image1_redirect.jpg", RasterImageFormat.Jpeg, image.BitsPerPixel)    codecs.StopRedirecting()    ' Clean up    myStream.Dispose()    image.Dispose()    codecs.Dispose()    RasterCodecs.Shutdown() End Sub

C#

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// Redirect Read event example  FileStream myStream;  // Redirect Open event example  private void Codecs_Open(object sender, CodecsRedirectOpenEventArgs e)  {     myStream = new FileStream(e.FileName, e.Mode);     e.Success = true;  }    // Redirect Seek event example  private void Codecs_Seek(object sender, CodecsRedirectSeekEventArgs e)  {     myStream.Seek(e.Offset, e.Origin);  }    // Redirect Read event example  private void Codecs_Read(object sender, CodecsRedirectReadEventArgs e)  {     byte[] byteBuffer = new byte[e.Count];     myStream.Read(byteBuffer, 0, e.Count);     Marshal.Copy(byteBuffer, 0, e.Buffer, e.Count);     e.Read = e.Count;     Console.WriteLine("The number of bytes that read request should copy to the buffer is : {0}", e.Count);     Console.WriteLine("The actual number of bytes that this read request has copied to Buffer is : {0}", e.Read);  }    // Redirect Write event example  private void Codecs_Write(object sender, CodecsRedirectWriteEventArgs e)  {     byte[] byteBuffer = new byte[e.Count];     Marshal.Copy(e.Buffer, byteBuffer, 0, e.Count);     e.Written = e.Count;     myStream.Write(byteBuffer, 0, e.Count);       Console.WriteLine("The number of bytes that write request should copy from the buffer is : {0}", e.Count);     Console.WriteLine("The actual number of bytes that this write request has copied from Buffer is : {0}", e.Written);  }    // Redirect Close event example  private void Codecs_Close(object sender, CodecsRedirectCloseEventArgs e)  {     myStream.Close();  }      public void StartRedirectingExample()  {     RasterCodecs.Startup();     RasterCodecs codecs = new RasterCodecs();       codecs.RedirectOpen += new EventHandler<CodecsRedirectOpenEventArgs>(Codecs_Open);     codecs.RedirectSeek += new EventHandler<CodecsRedirectSeekEventArgs>(Codecs_Seek);     codecs.RedirectRead += new EventHandler<CodecsRedirectReadEventArgs>(Codecs_Read);     codecs.RedirectWrite += new EventHandler<CodecsRedirectWriteEventArgs>(Codecs_Write);     codecs.RedirectClose += new EventHandler<CodecsRedirectCloseEventArgs>(Codecs_Close);       string srcFilename = LeadtoolsExamples.Common.ImagesPath.Path + "Image1.cmp";       codecs.StartRedirecting();     RasterImage image = codecs.Load(srcFilename);     myStream.Close();     codecs.Save(image,  LeadtoolsExamples.Common.ImagesPath.Path + "Image1_redirect.jpg", RasterImageFormat.Jpeg, image.BitsPerPixel);     codecs.StopRedirecting();       // Clean up     myStream.Dispose();     image.Dispose();     codecs.Dispose();     RasterCodecs.Shutdown();  }

LEADTOOLS I/O redirection allows you to replace the default input/output methods for opening, reading, writing, seeking, and closing files.

For example, you can redirect all the library I/O methods to your own I/O methods to load/save images from your own streams.

Once you call StartRedirecting, all subsequent file I/O operation will fire the following events:

Event	Operation
RedirectOpen	When the toolkit is trying to open a file
RedirectRead	When the toolkit is trying to reading from a file
RedirectWrite	When the toolkit is trying to writing to a file
RedirectSeek	When the toolkit is trying to seeking into a file
RedirectClose	When the toolkit is trying to closing a file

Call StopRedirecting to reset the I/O methods back to the defaults.

Target Platforms: Microsoft .NET Framework 3.0, Windows XP, Windows Server 2003 family, Windows Server 2008 family

Reference