EnumTags(Stream,int) Method

Summary

Enumerates all the tags in a stream.

Syntax

Objective-C

C++/CLI

Java

Python

public void EnumTags( 
   Stream stream, 
   int pageNumber 
)

- (BOOL)enumerateTagsInStream:(LTLeadStream *)stream  
                   pageNumber:(NSInteger)pageNumber  
                     callback:(void (^)(LTCodecsEnumTagsEventArgs *tagInfo))handler  
                        error:(NSError **)error

public void enumTags(ILeadStream stream, int pageNumber)

public: 
void EnumTags(  
   Stream^ stream, 
   int pageNumber 
)

def EnumTags(self,stream,pageNumber):

Parameters

stream
A Stream containing the input file image data.

pageNumber
1-based index of the page from which to enumerate the tags.

Remarks

This method will fire the TagFound event for each tag found in the stream.

Currently, only TIFF and Exif files contain tags.

For multipage TIFF files, you can enumerate the tags from a particular page. Specify the page number whose tags to enumerate.

This method enumerates the standard TIFF tags and the user tags. Standard TIFF tags are less than 32767. User TIFF tags are usually between 32768 and 65535.

To enumerate the tags stored in a disk file, use EnumTags.

To read a tag value, use ReadTag and to read all the tags in a file, use ReadTags.

For general information about TIFF tags, refer to Implementing TIFF Comments and Tags.

Do not attempt to use DeleteTag to delete tags from inside the TagFound event. If you want to delete tags that you enumerate, use this event to add the tags to a list. Upon returning from EnumTags, you can delete all the tags from the list.

You can use TagsSupported to determine whether a certain file format supports tags.

Example

Java

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.Svg; 
 
 
string tagsFileName; 
IList<RasterTagMetadata> myTags; 
 
void EnumTagsExample(string srcFileName, string destFileName) 
{ 
   RasterCodecs codecs = new RasterCodecs(); 
 
   tagsFileName = srcFileName; 
   myTags = new List<RasterTagMetadata>(); 
 
   codecs.TagFound += new EventHandler<CodecsEnumTagsEventArgs>(codecs_TagFound); 
   codecs.EnumTags(srcFileName, 1); 
   codecs.TagFound -= new EventHandler<CodecsEnumTagsEventArgs>(codecs_TagFound); 
 
   // We read all the tags now, save them to the file 
   Debug.WriteLine("{0} tags read, saving them to the destination file", myTags.Count); 
   codecs.WriteTags(destFileName, 1, myTags); 
 
   // Clean up 
   codecs.Dispose(); 
} 
 
void codecs_TagFound(object sender, CodecsEnumTagsEventArgs e) 
{ 
   Debug.WriteLine("Tag: Id={0}, Count={1}, Type={2}, Cancel={3}", e.Id, e.Count, e.MetadataType, e.Cancel); 
 
   // Read this tag from the file and add it to our collection 
   RasterCodecs codecs = sender as RasterCodecs; 
   RasterTagMetadata tag = codecs.ReadTag(tagsFileName, 1, e.Id); 
   myTags.Add(tag); 
}

 
import java.io.*; 
import java.net.*; 
import java.nio.file.Paths; 
import java.util.*; 
import java.time.Instant; 
import java.time.Duration; 
 
import org.junit.*; 
import org.junit.runner.JUnitCore; 
import org.junit.runner.Result; 
import org.junit.runner.notification.Failure; 
import static org.junit.Assert.*; 
 
import leadtools.*; 
import leadtools.codecs.*; 
import leadtools.codecs.RasterCodecs.FeedCallbackThunk; 
import leadtools.drawing.internal.*; 
import leadtools.imageprocessing.*; 
import leadtools.imageprocessing.color.ChangeIntensityCommand; 
import leadtools.svg.*; 
 
 
String tagsFileName; 
RasterCollection<RasterTagMetadata> myTags; 
 
public void enumTagsExample() throws IOException { 
   final String LEAD_VARS_IMAGES_DIR = "C:\\LEADTOOLS23\\Resources\\Images"; 
   String srcFileName = combine(LEAD_VARS_IMAGES_DIR, "ocr1-4.tif"); 
   RasterCodecs codecs = new RasterCodecs(); 
 
   tagsFileName = srcFileName; 
   myTags = new RasterCollection<RasterTagMetadata>(); 
 
   ILeadStream srcFileStream = LeadStreamFactory.create(srcFileName); 
   codecs.addTagFoundListener(codecsTagFound); 
   codecs.enumTags(srcFileStream, 1); 
   codecs.removeTagFoundListener(codecsTagFound); 
 
   // We read all the tags now, save them to the file 
   System.out.println(myTags.size() + " tags read, saving them to the destination file"); 
   ILeadStream destFileStream = LeadStreamFactory.create(srcFileName); 
   codecs.writeTags(destFileStream, 1, myTags); 
 
   // Clean up 
   destFileStream.close(); 
   srcFileStream.close(); 
   codecs.dispose(); 
} 
 
CodecsTagFoundListener codecsTagFound = new CodecsTagFoundListener() { 
 
   @Override 
   public void onTagFound(CodecsEnumTagsEvent e) { 
      System.out.println("Tag: Id=" + e.getId() + ", Count=" + e.getCount() + ", Type=" + e.getMetadataType() 
            + ", Cancel=" + e.getCancel()); 
 
      // Read this tag from the file and add it to our collection 
      RasterCodecs codecs = (RasterCodecs) e.getSource(); 
      ILeadStream ls = LeadStreamFactory.create(tagsFileName); 
      RasterTagMetadata tag = codecs.readTag(ls, 1, e.getId()); 
      myTags.add(tag); 
      try { 
         ls.close(); 
      } catch (IOException e1) { 
         e1.printStackTrace(); 
      } 
   } 
 
};

Requirements

Target Platforms

Reference

RasterCodecs Class

RasterCodecs Members

Overload List

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Help Version 23.0.2024.2.29

Leadtools.Codecs Assembly

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