WriteTag(Stream,int,RasterTagMetadata) Method

Summary

Writes or changes a tag to an existing stream.

Syntax

Objective-C

C++/CLI

Java

Python

public void WriteTag( 
   Stream stream, 
   int pageNumber, 
   RasterTagMetadata tag 
)

- (BOOL)writeTag:(nullable LTRasterTagMetadata *)tag  
        toStream:(LTLeadStream *)stream  
      pageNumber:(NSInteger)pageNumber  
           error:(NSError **)error

public void writeTag(ILeadStream stream, int pageNumber, RasterTagMetadata tag)

public: 
void WriteTag(  
   Stream^ stream, 
   int pageNumber, 
   RasterTagMetadata^ tag 
)

def WriteTag(self,stream,pageNumber,tag):

Parameters

stream
A Stream that contains the file data.

pageNumber
1-based index of the page at which to write the tag.

tag
Tag to identify the data in the TIFF file.

Remarks

This method writes tags into an existing file or changes tags in an existing file.

This method with TIFF and other files that support Exif metadata (JPEG, PNG).

Note Use this method carefully. LEADTOOLS will not restrict the tags that you write. If you write bad tags, the file might become corrupted. Consult the TIFF documentation for a list of predefined tags. It is recommended that you write only the user-defined tags (the tags between 0x8000 and 0xFFFF).

See the TIFF documentation for a complete list of the TIFF tags and types.

When you add or remove tags, the tags array at the end of the file is re-written. When you modify existing tags, the new tag value is added to the file and the IFD is modified as necessary. In all of these cases, there is no image recompression.

Some restrictions apply to this function if you use an IFD to indicate to which page to write the tag. See the Loading and Saving Large TIFF / BigTIFF Files topic for more information.

Example

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.Svg; 
 
 
 
public void TagExample() 
{ 
   RasterCodecs codecs = new RasterCodecs(); 
 
   string srcFileName = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp"); 
   string destFileName = Path.Combine(LEAD_VARS.ImagesDir, "Image1_CustomTag.tif"); 
 
   // Convert the source file to TIF 
   Debug.WriteLine("Converting the source file to TIF"); 
   codecs.Convert(srcFileName, destFileName, RasterImageFormat.Tif, 0, 0, 24, null); 
 
   const int customTagId = 0x8000; /* 32768 in decimal */ 
   int customTagValue = 7; 
 
   RasterTagMetadata writeTag = new RasterTagMetadata(); 
   writeTag.Id = customTagId; 
   writeTag.DataType = RasterTagMetadataDataType.Int32; 
   writeTag.FromInt32(new int[] { customTagValue }); 
 
   Debug.WriteLine("Writing the following tag to the file:"); 
   Debug.WriteLine("  ID: {0}", writeTag.Id); 
   Debug.WriteLine("  DataType: {0}", writeTag.DataType); 
   Console.Write("  Data: "); 
   byte[] writeTagData = writeTag.GetData(); 
   for (int i = 0; i < writeTagData.Length; i++) 
      Console.Write("{0:X} ", writeTagData[i]); 
   Debug.WriteLine(" "); 
 
   // Add the tag 
   Debug.WriteLine("Writing the custom tag with data = {0} to the file", customTagValue); 
   codecs.WriteTag(destFileName, 1, writeTag); 
 
   // Read the tag and make sure its in the file 
   Debug.WriteLine("Reading the custom tag from the file"); 
   RasterTagMetadata readTag = codecs.ReadTag(destFileName, 1, customTagId); 
 
   Debug.WriteLine("Tag read from the file:"); 
   Debug.WriteLine("  ID: {0}", readTag.Id); 
   Debug.WriteLine("  DataType: {0}", readTag.DataType); 
   Console.Write("  Data: "); 
   byte[] readTagData = readTag.GetData(); 
   for (int i = 0; i < readTagData.Length; i++) 
      Console.Write("{0:X} ", readTagData[i]); 
   Debug.WriteLine("  "); 
 
   Debug.Assert(writeTag.Id == readTag.Id); 
   Debug.Assert(writeTag.DataType == readTag.DataType); 
   Debug.Assert(writeTagData.Length == writeTagData.Length); 
   for (int i = 0; i < writeTagData.Length; i++) 
      Debug.Assert(writeTagData[i] == readTagData[i]); 
 
   // Delete the tag from the file 
   Debug.WriteLine("Deleting the tag from the file"); 
   codecs.DeleteTag(destFileName, 1, customTagId); 
 
   // Make sure the tag is deleted 
   Debug.WriteLine("Reading the tag from the file again"); 
   readTag = codecs.ReadTag(destFileName, 1, customTagId); 
 
   if (readTag == null) 
      Debug.WriteLine("Tag was not found"); 
   else 
      Debug.WriteLine("Tag is found, this should not happen"); 
 
   Debug.Assert(readTag == null); 
 
   // Clean up 
   codecs.Dispose(); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images"; 
}

Requirements

Target Platforms

Reference

RasterCodecs Class

RasterCodecs Members

Overload List

Implementing TIFF Comments and Tags

Working with Markers

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Help Version 22.0.2023.5.5

Leadtools.Codecs Assembly

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