References ▼
Called for each capability enumerated by the L_TwainEnumCapabilities function. The address of this callback is passed as an argument in L_TwainEnumCapabilities.
#include "lttwn.h"
L_INT pEXT_CALLBACK YourFunction (hSession, uCap, pCapabiltiy, pUserData)
Handle to an existing TWAIN session. This handle is obtained by calling the L_TwainInitSession or L_TwainInitSession2 function.
The capability being enumerated. For more information on capability values, refer to the TWAIN specification.
Pointer to the TW_CAPABILITY structure that references the capability data being enumerated. For more information about TW_CAPABILITY, refer to the TWAIN specification.
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 L_TwainEnumCapabilities.)
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. |
To prevent memory leaks, the user should free the pointer to TW_CAPABILITY structure within the callback function.
For an example, refer to L_TwainStartCapsNeg.