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StartRedirecting Method
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Leadtools.Codecs Namespace > RasterCodecs Class : StartRedirecting Method




Starts file I/O redirection.

Syntax

Visual Basic (Declaration) 
Public Sub StartRedirecting()
Visual Basic (Usage)Copy Code
Dim instance As RasterCodecs
 
instance.StartRedirecting()
C# 
public void StartRedirecting()
Managed Extensions for C++ 
public: void StartRedirecting();
C++/CLI 
public:
void StartRedirecting();

Example

Visual BasicCopy Code
RasterCodecs.StartRedirecting
      ' 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 = "C:\Program Files\LEAD Technologies\LEADTOOLS 15\Images\Image1.cmp"

         codecs.StartRedirecting()
         Dim image As RasterImage = codecs.Load(srcFilename)
         myStream.Close()
         codecs.Save(image, "C:\Program Files\LEAD Technologies\LEADTOOLS 15\Images\Image1_redirect.jpg", RasterImageFormat.Jpeg, image.BitsPerPixel)
         codecs.StopRedirecting()

         ' Clean up
         myStream.Dispose()
         image.Dispose()
         codecs.Dispose()
         RasterCodecs.Shutdown()
      End Sub
C#Copy Code
RasterCodecs.StartRedirecting 
      // 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 = @"C:\Program Files\LEAD Technologies\LEADTOOLS 15\Images\Image1.cmp"; 
 
         codecs.StartRedirecting(); 
         RasterImage image = codecs.Load(srcFilename); 
         myStream.Close(); 
         codecs.Save(image, @"C:\Program Files\LEAD Technologies\LEADTOOLS 15\Images\Image1_redirect.jpg", RasterImageFormat.Jpeg, image.BitsPerPixel); 
         codecs.StopRedirecting(); 
 
         // Clean up 
         myStream.Dispose(); 
         image.Dispose(); 
         codecs.Dispose(); 
         RasterCodecs.Shutdown(); 
      }

Remarks

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:

EventOperation
RedirectOpenWhen the toolkit is trying to open a file
RedirectReadWhen the toolkit is trying to reading from a file
RedirectWriteWhen the toolkit is trying to writing to a file
RedirectSeekWhen the toolkit is trying to seeking into a file
RedirectCloseWhen the toolkit is trying to closing a file

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

Requirements

Target Platforms: Microsoft .NET Framework 2.0, Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also