StartRedirecting Method

Summary

Starts file I/O redirection.

Syntax

C++

Java

public void StartRedirecting()

Public Sub StartRedirecting()

public void startRedirecting()

public: 
void StartRedirecting();

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:

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.

Example

This example demonstrates overriding the default IO routines.

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.Svg; 
 
 
// 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); 
	e.Offset = myStream.Position; 
} 
 
// 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); 
	myStream.Write(byteBuffer, 0, e.Count); 
	e.Written = 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:\LEADTOOLS21\Resources\Images"; 
}

Requirements

Target Platforms

Reference

RasterCodecs Class

RasterCodecs Members

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Help Version 21.0.2021.7.2

Leadtools.Codecs Assembly

Introduction

Getting Started

Namespaces

Leadtools.Codecs Namespace

Assemblies