ENUMTAGSCALLBACK

#include "l_bitmap.h"

L_INT pEXT_CALLBACK YourFunction (uTag, uType, uCount, pUserData)

L_EnumFileTags calls this callback for each tag present on the page.

Parameters

L_UINT16 uTag

Tag to identify the data in the TIFF file. This may be any tag specified in L_SetTag, or any other tag added by the TIFF filter when saving the file. For example, all of the TIFF comments would generate a particular TIFF tag.

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.

L_UINT32 uCount

Number of elements of type uType. Note that this is not the same as the number of bytes. For example, if uCount is 10 and uType is TAG_LONG, you will need 10 x 4 = 40 bytes to read the tag data.

L_VOID * pUserData

A void pointer that you can use to access a variable or structure containing data that your callback function needs. This gives you a way to receive data indirectly from the function that uses this callback function. (This is the same pointer that you pass in the pUserData parameter of the L_EnumMarkers function.)

Keep in mind that this is a void pointer, which must be cast to the appropriate data type within your callback function.

Returns

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

Comments

L_EnumFileTags calls this callback for each tag in the page.

Do not attempt to use the L_DeleteTag function to delete tags from inside an ENUMTAGSCALLBACK callback function. If you want to delete tags that you enumerate, use ENUMTAGSCALLBACK to add the tags to a list. Upon returning from L_EnumFileTags, you can delete all the tags from the list.

Required DLLs and Libraries

See Also

Functions

Topics

Example

For an example, refer to L_ReadFileTag.

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