ReadExtensions(Stream,int) Method

Summary

Loads extensions from the specified EXIF stream.

Syntax

Objective-C

C++/CLI

Java

Python

public CodecsExtensionList ReadExtensions( 
   Stream stream, 
   int pageNumber 
)

- (nullable LTCodecsExtensionList *)readExtensionsFromStream:(LTLeadStream *)stream  
                                                  pageNumber:(NSInteger)pageNumber  
                                                       error:(NSError **)error

public CodecsExtensionList readExtensions(ILeadStream stream, int pageNumber)

public: 
CodecsExtensionList^ ReadExtensions(  
   Stream^ stream, 
   int pageNumber 
)

def ReadExtensions(self,stream,pageNumber):

Parameters

stream
The input file data stream.

pageNumber
1-based index of the page within the file that contains the extension.

Return Value

An CodecsExtensionList object that contains the extensions found in this file.

Remarks

Please note that not all Exif files have extensions.

Currently, this method works only with Exif files. Exif files can contain extra data stored as "FlashPix extensions". This method can be used to access this extra data. Leadtools refers to this extra data as "extensions".

You must dispose the CodecsExtensionList returned from this method when you are done using it.

Example

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.Svg; 
 
 
public void ExtensionsExample(string exifFileName) 
{ 
   RasterCodecs codecs = new RasterCodecs(); 
 
   string stampFileName = Path.Combine(LEAD_VARS.ImagesDir, "Extension.bmp"); 
   string audioFileNameTemplate = Path.Combine(LEAD_VARS.ImagesDir, "Extension.wav"); 
 
   // Read the extensions from the file 
   Debug.WriteLine("Reading the extensions from the exif file"); 
   CodecsExtensionList extensionList = codecs.ReadExtensions(exifFileName, 1); 
   if (extensionList != null) 
   { 
      if ((extensionList.Flags & CodecsExtensionListFlags.Stamp) == CodecsExtensionListFlags.Stamp) 
      { 
         Debug.WriteLine("Stamp extension: Found, saving to {0}", stampFileName); 
         RasterImage stampImage = extensionList.CreateStamp(); 
         codecs.Save(stampImage, stampFileName, RasterImageFormat.Bmp, 24); 
         stampImage.Dispose(); 
      } 
      else 
         Debug.WriteLine("Stamp extension: Not found"); 
 
      if ((extensionList.Flags & CodecsExtensionListFlags.Audio) == CodecsExtensionListFlags.Audio) 
      { 
         Debug.WriteLine("Audio extension: Found, saving ..."); 
         RasterNativeBuffer audioData; 
         int streamIndex = 0; 
 
         do 
         { 
            audioData = extensionList.GetAudioData(streamIndex); 
            if (audioData.Data != IntPtr.Zero) 
            { 
               string audioFileName = string.Format(audioFileNameTemplate, streamIndex); 
               Debug.WriteLine("To {0}", audioFileName); 
               using (FileStream fs = File.Create(audioFileName)) 
               { 
                  byte[] data = new byte[audioData.Length]; 
                  Marshal.Copy(audioData.Data, data, 0, (int)audioData.Length); 
                  fs.Write(data, 0, (int)audioData.Length); 
               } 
 
               streamIndex++; 
            } 
         } 
         while (audioData.Data != IntPtr.Zero); 
 
         Debug.WriteLine("{0} total audio streams found", streamIndex); 
      } 
      else 
         Debug.WriteLine("Audio extension: Not found"); 
 
      CodecsExtension[] extensions = extensionList.GetExtensions(); 
      Debug.WriteLine("Total number of extensions found in the file: {0}", extensions.Length); 
 
      for (int i = 0; i < extensions.Length; i++) 
      { 
         CodecsExtension extension = extensions[i]; 
         Debug.WriteLine(" {0}. Name: {1}, Clsid: {2}, UCDefault: {3}, DatLength: {4}", 
            i, extension.Name, extension.Clsid, extension.UCDefault, extension.DataLength); 
      } 
 
      // Finalize cannot be called directly, it is invoked automatically. 
      // To clean up before exiting, use Dispose 
      extensionList.Dispose(); 
   } 
   else 
      Debug.WriteLine("No extensions were found in the file"); 
 
   codecs.Dispose(); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images"; 
}

Requirements

Target Platforms

Reference

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Help Version 22.0.2023.5.5

Leadtools.Codecs Assembly

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