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LFile::WriteTag

Summary

Writes tags to a file or changes existing tags in a file.

Syntax

#include "ltwrappr.h"

virtual L_INT LFile::WriteTag(pSaveOptions)

Parameters

pSAVEFILEOPTION pSaveOptions

Pointer to optional extended save options. Pass NULL to use the default save options. pSaveOptions.PageNumber indicates the page on which to write the tags. Note that an error code will be returned if the page does not exist.

Returns

Value	Meaning
SUCCESS	The function was successful.
< 1	An error occurred. Refer to Return Codes.

Comments

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

This function will write all the tags that have been set using LFileSettings::SetTag. There must be at least one tag set for this function to work. If no tags have been set, an error will be returned by this function.

This function works only with TIFF files.

Note: Use this function 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).

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

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

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

Required DLLs and Libraries

LTFIL
File format DLLs
For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

Platforms

Win32, x64.

Example

L_INT LFile__WriteTagExample() 
{ 
   L_INT nRet; 
   L_UINT16 LogoPosition = 0x8001; /* my private tag */ 
   L_UINT16 TagType = TAG_SHORT; /* tagged data type */ 
   L_UINT32 TagCount = 4; /* count of data items */ 
   L_INT16 TagData[] = {5, 5, 24, 37}; 
   L_VOID * pTagData = &TagData; /* pointer to the buffer containing the data */ 
   SAVEFILEOPTION SaveFileOption; 
   LFileSettings MyFileSettings; 
   LFile MyFile; 
 
   /* Set the tag data to be saved */ 
   nRet = MyFileSettings.SetTag(LogoPosition, TagType, TagCount, pTagData); 
   if(nRet != SUCCESS) 
      return nRet; 
 
   MyFile.GetDefaultSaveFileOption (&SaveFileOption, sizeof(SAVEFILEOPTION)); 
 
   SaveFileOption.PageNumber = 1; 
 
   MyFile.SetFileName(MAKE_IMAGE_PATH(TEXT("clean.tif"))); 
 
   /* Save the file with the tag. Note that input file must exist and contain at least one page! */ 
   nRet = MyFile.WriteTag(&SaveFileOption); 
   if(nRet != SUCCESS) 
      return nRet; 
 
   /* Clear the tag from memory */ 
   nRet = MyFileSettings.SetTag(0, 0, 0, NULL); 
   if(nRet != SUCCESS) 
      return nRet; 
 
   return SUCCESS; 
}