RedirectRead Event

Summary

Replaces the normal LEADTOOLS method for reading from a file.

Syntax

C++/CLI

Java

Python

public event EventHandler<CodecsRedirectReadEventArgs> RedirectRead

synchronized public void addRedirectReadListener(CodecsRedirectReadListener listener) 
synchronized public void removeRedirectReadListener(CodecsRedirectReadListener listener)

public: 
event EventHandler<CodecsRedirectReadEventArgs^>^ RedirectRead

def RedirectRead(sender,e): # sender: RasterCodecs e: CodecsRedirectReadEventArgs

Event Data

The event handler receives an argument of type CodecsRedirectReadEventArgs containing data related to this event. The following CodecsRedirectReadEventArgs properties provide information specific to this event.

Property	Description
Buffer	Gets a pointer to the unmanaged memory buffer into which this read operation should copy the data.

Remarks

You can redirect all the toolkit I/O methods to your own I/O methods to load/save images from your own streams.

To replace the normal method for reading from a file, set your own subscribe to this event then call the StartRedirecting method.

Example

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); 
   Console.WriteLine("Access: {0}, Share: {1}", e.Access, e.Share); 
   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; 
   Debug.WriteLine("The number of bytes that read request should copy to the buffer is : {0}", e.Count); 
   Debug.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; 
 
   Debug.WriteLine("The number of bytes that write request should copy from the buffer is : {0}", e.Count); 
   Debug.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, "test_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:\LEADTOOLS22\Resources\Images"; 
}

Requirements

Target Platforms

Reference

RasterCodecs Class

RasterCodecs Members

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Help Version 22.0.2023.5.5

Leadtools.Codecs Assembly

Introduction

Getting Started

Namespaces

Leadtools.Codecs Namespace

Assemblies