StartRedirecting Method

public void StartRedirecting()

public void StartRedirecting()

 function Leadtools.Codecs.RasterCodecs.StartRedirecting()

public:
void StartRedirecting();

'Declaration
 
Public Sub StartRedirecting()

'Usage
 
Dim instance As RasterCodecs
 
instance.StartRedirecting()

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.

Visual Basic
C#

' 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()
      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 = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp")

      codecs.StartRedirecting()
      Dim image As RasterImage = codecs.Load(srcFilename)
      myStream.Close()
      codecs.Save(image, Path.Combine(LEAD_VARS.ImagesDir, "Image1_redirect.jpg"), RasterImageFormat.Jpeg, image.BitsPerPixel)
      codecs.StopRedirecting()

      ' Clean up
      myStream.Dispose()
      image.Dispose()
      codecs.Dispose()
   End Sub

Public NotInheritable Class LEAD_VARS
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images"
End Class

// 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 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 = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp");

         codecs.StartRedirecting();
         RasterImage image = codecs.Load(srcFilename);
         myStream.Close();
         codecs.Save(image, Path.Combine(LEAD_VARS.ImagesDir, "Image1_redirect.jpg"), RasterImageFormat.Jpeg, image.BitsPerPixel);
         codecs.StopRedirecting();

         // Clean up
         myStream.Dispose();
         image.Dispose();
         codecs.Dispose();
     }

static class LEAD_VARS
{
   public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images";
}

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

RasterCodecs Class
RasterCodecs Members