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L_SetTag

#include "l_bitmap.h"

L_LTFIL_API L_INT L_SetTag(uTag, uType, uCount, pData)

Specifies a private tag and the tagged data to be saved in a TIFF file.

Parameters

L_UINT16 uTag

Tag to identify the data in the TIFF file. Generally, you can specify a private tag in the range of 0x8000 to 0xFFFE. However, LEADTOOLS returns an error if you use any of the following registered tags:

Value	Meaning
0x8298	Copyright comment
0x8769	General Exif comments
0x8825	Exif GPS comments

LEADTOOLS does NOT return an error if you set:

Value	Meaning
0x80A4	Annotation TIFF tag defined as ANNTAG_TIFF.

L_UINT16 uType

Tagged data type. Valid values are:

Value	Meaning
TAG_BYTE	[1] Byte.
TAG_ASCII	[2] Byte in the range of 0 to 255.
TAG_SBYTE	[6] Byte used as signed number in the range of -128 to +127.
TAG_UNDEFINED	[7] Byte, with application-defined usage.
TAG_SHORT	[3] Two bytes, unsigned.
TAG_SSHORT	[8] Two bytes, signed.
TAG_LONG	[4] Four bytes, unsigned.
TAG_SLONG	[9] Four bytes, signed.
TAG_RATIONAL	[5] Eight bytes, used as a pair of unsigned long integers, where the first number is the numerator and the second is the denominator of a fraction.
TAG_SRATIONAL	[10] Eight bytes, used as a pair of signed long integers, where the first number is the numerator and the second is the denominator of a fraction.
TAG_FLOAT	[11] Four bytes used as a floating point number.
TAG_DOUBLE	[12] Eight bytes used as a double-precision floating point number.
TAG_IFD	[13] 32-bit IFD offset.
TAG_LONG8	[16] Unsigned 64-bit integer (valid only for BigTIFF formats).
TAG_SLONG8	[17] Signed 64-bit integer (valid only for BigTIFF formats).
TAG_IFD8	[18] 64-bit IFD offset (valid only for BigTIFF formats).

L_UINT uCount

Count of data items, based on the tagged data type. For example, if the buffer size is 16 and the data type is TAG_DOUBLE, the count is 2.

L_VOID* pData

Pointer to a buffer containing the data to be saved using the tag.

Returns

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

Comments

This function copies the data from your buffer to an internally-allocated buffer. You should free your own buffer after calling this function. Any TIFF file that you save will include the tagged data until you clear the tag. LEADTOOLS keeps a list of tags in memory. The list contains all the tags set directly (by calling L_SetTag) or indirectly (by calling L_AnnSaveTag). All these tags will be saved unless you clear them. The way to clear a tag and remove it from the list is by calling L_SetTag(uTag, 0, 0, NULL). L_SetTag(0,0,0,NULL) will remove ALL the tags from the tag list.

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

Notes:

When LEADTOOLS saves a TIFF/Exif image that contains comments and tags, the comments and tags will be written first, followed by the image data. This order is not configurable.
To write tags to a TIFF file, use L_WriteFileTag or L_WriteFileTagMemory instead of using L_SetTag followed by L_SaveFile or L_SaveFileMemory.

Required DLLs and Libraries

LTFIL
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, Linux.

Functions

Topics

Implementing TIFF Comments and Tags

Example

This example specifies a tag for recording the position of a company logo on the image. It sets the tag with L_SetTag; tests the tag with L_GetTag; then saves a TIFF file with the new tag. For an example that reads this same tag from the file, refer to L_ReadFileTag.

L_INT SetTagExample(pBITMAPHANDLE pBitmap) 
{ 
   L_INT nRet; 
   L_TCHAR msgbuf[80];             /* buffer for the message string */ 
   L_UINT16 LogoPosition = 0x8001; /* my private tag                */ 
   L_UINT16 TagType = TAG_SSHORT;  /* tagged data type              */ 
   L_UINT32 TagCount = 4;          /* count of data items           */ 
   L_INT TagData[] = {5, 5, 24, 37}; 
   L_VOID * pTagData = &TagData;   /* pointer to the buffer containing the data */ 
 
   /* Set the tag data to be saved */ 
   nRet = L_SetTag(LogoPosition, TagType, TagCount, pTagData); 
   if(nRet != SUCCESS) 
      return nRet; 
 
   /* Clear the variables so that we can validate the data */ 
   TagType = 0; 
   TagCount = 0; 
   TagData[0] = 0; 
   TagData[1] = 0; 
   TagData[2] = 0; 
   TagData[3] = 0; 
 
   /* Get the tag data that is ready to be saved */ 
   nRet = L_GetTag(LogoPosition, &TagType, &TagCount, pTagData); 
   if(nRet < SUCCESS) 
      return nRet; 
 
   /* Display a message showing the data */ 
   if ((TagType == TAG_SSHORT) && (TagCount == 4)) 
   { 
      wsprintf(msgbuf, TEXT("X = %d\nY= %d\nWidth = %d\nHeight = %d"), 
               ((L_INT  *)pTagData)[0], 
               ((L_INT  *)pTagData)[1], 
               ((L_INT  *)pTagData)[2], 
               ((L_INT  *)pTagData)[3]); 
      MessageBox (NULL, msgbuf, TEXT("Logo Position"), MB_OK); 
   } 
   /* Save the file with the tag */ 
   nRet = L_SaveBitmap(MAKE_IMAGE_PATH(TEXT("TEST.TIF")), pBitmap, FILE_TIF, pBitmap->BitsPerPixel, 0, NULL); 
   if(nRet != SUCCESS) 
      return nRet; 
 
   /* Clear the tag from memory */ 
   nRet = L_SetTag(0, 0, 0, NULL); 
 
   return SUCCESS; 
}

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