In This Topic ▼

LFileSettings::SetTag

Summary

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

Syntax

#include "ltwrappr.h"

static L_INT LFileSettings::SetTag(uTag, uType, uCount, pData)

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:

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

LEADTOOLS does NOT return an error if you set:

Tag	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_UINT32 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 LFileSettings::SetTag) or indirectly (by calling LAnnContainer::SaveTag). 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 LFileSettings::SetTag(uTag, 0, 0, NULL). LFileSettings::SetTag(0,0,0,NULL) will remove ALL the tags from the tag list.

Note

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 LFile::WriteTag instead of using LFileSettings::SetTag followed by LFile::Save or LMemoryFile::Save.

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