LTWAINSETPROPERTYCALLBACK Function

#include "lttwn.h"

L_INT pEXT_CALLBACK YourFunction (hSession, uCap, nStatus, pValue, pUserData)

HTWAINSESSION hSession;

handle to an existing TWAIN session

L_UINT uCap;

capability being set

L_INT nStatus;

status variable

L_VOID * pValue;

pointer to the original value

L_VOID * pUserData;

pointer to additional parameters

Called for each property set. The address of this callback is passed as an argument to L_TwainSetProperties.

Parameter

Description

hSession

Handle to an existing TWAIN session. This handle is obtained by calling the L_TwainInitSession or L_TwainInitSession2 function.

uCap

The capability being set.

nStatus

This variable holds the value of the error that occurred while the property was being set.

pValue

Pointer to the original value. The user can cast this depending on the type of the property, and modify it.

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_TwainSetProperties.)

 

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

Returns

SUCCESS

The function was successful.

TWAIN_SUCCESS_RETRY

Retry with the new value in *pValue parameter.

TWAIN_SUCCESS_ABORT

Abort the negotiation.

Comments

The user should not free the pValue parameter within this callback.

Required DLLs and Libraries

LTTWN

For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files to be Included with your Application.

See Also

Functions:

L_TwainSetProperties.

Topics:

TWAIN Functionality: Callback Functions

Example

For an example, refer to L_TwainGetProperties.

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