#include "lttwn.h"

L_INT pEXT_CALLBACK YourFunction (hSession, pCapability, nStatus, pUserData)

Called for each capability being loaded from the template file or saved from the TWAIN source. The address of this callback is passed as an argument L_TwainLoadTemplateFile and L_TwainSaveTemplateFile.



Handle to an existing TWAIN session.

pTW_CAPABILITY * pCapability

Pointer to a TW_CAPABILITY structure that contains the capability.  For information on this structure, refer to the TWAIN specification.

L_INT nStatus

When used with L_TwainLoadTemplateFile, nStatus refers to whether pCapability was set successfully.  When used with L_TwainSaveTemplateFile, nStatus refers to whether the pCapability was successfully added to the template file.

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 L_TwainLoadTemplateFile or L_TwainSaveTemplateFile.)

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


Value Meaning
TWAIN_SUCCESS The function was successful.
TWAIN_SUCCESS_ABORT The callback wants to abort the operation.
< 1 An error occurred. Refer to Return Codes.


Use this callback to alert the user of any failures in setting a capability when loaded from a template file.  You can also use this callback to provide a listing of all capabilities and their possible values found in a template file or being saved to a template file.

Required DLLs and Libraries

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