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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.
#include "lttwn.h"
L_INT pEXT_CALLBACK YourFunction (hSession, pCapability, nStatus, pUserData)
Handle to an existing TWAIN session.
Pointer to a TW_CAPABILITY structure that contains the capability. For information on this structure, refer to the TWAIN specification.
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.
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.
For an example, refer to L_TwainSaveTemplateFile.