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ENUMGEOKEYSCALLBACK

Summary

This function is called for each GeoKey enumerated by the L_EnumFileGeoKeys function.

Syntax

#include "l_bitmap.h"

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

Parameters

L_UINT16 uType

The type of GeoKey. This indicates whether the data pointed to by pData is SHORT, DOUBLE or ASCII. Possible values are:

Value	Meaning
TAG_ASCII	[2] Byte in the range of 0 to 255. Null-terminated.
TAG_SHORT	[3] Two bytes, unsigned.
TAG_DOUBLE	[12] Eight bytes used as a double-precision floating-point number.

L_UINT uCount

For TAG_ASCII, uCount represents the number of bytes in pData.

For TAG_SHORT and TAG_DOUBLE, uCount represents the number of items in the pData buffer.

Note that for TAG_SHORT and TAG_DOUBLE, uCount does not represent the number of bytes. Instead, it represents the number of items. For example, if uCount is 10 and uType is TAG_DOUBLE, you will need 10 x 8 = 80 bytes to read the tag data.

L_VOID* pData

A void pointer that you can use to access a variable or structure containing the GeoKey data. This gives you a way to receive data indirectly from the function that uses this callback function.

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_EnumFileGeoKeys function.)

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