This function is called for each GeoKey enumerated by the L_EnumFileGeoKeys function.
#include "l_bitmap.h"
L_INT pEXT_CALLBACK YourFunction(uTag, uType, uCount, pData, pUserData)
GeoKey ID identifying the GeoTIFF key.
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. |
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.
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.
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.
Value | Meaning |
---|---|
SUCCESS | The function was successful. |
< 1 | An error occurred. Refer to Return Codes. |
This function will be called for every GeoKey on the page.
For an example, refer to L_EnumFileGeoKeys.
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