LTWAINSETPROPERTYCALLBACK Function

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#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 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.

Functions:	L_TwainSetProperties.
Topics:	TWAIN Functionality: Callback Functions