LTWAINDEVICEEVENTCALLBACK

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#include "lttwn.h"

L_INT pEXT_CALLBACK YourFunction (hSession, pUserData);

HTWAINSESSION hSession;	/* handle to an existing TWAIN session */
L_VOID * pUserData;	/* pointer to additional parameters */

Called for each device event received when acquiring an image from the TWAIN source. The address of this callback is passed as an argument in L_TwainSetDeviceEventCallback.

Parameter

Description

hSession

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

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_TwainSetDeviceEventCallback.)

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.
< 1	An error occurred. Refer to Return Codes.

Comments

When the callback is fired, you can call L_TwainGetDeviceEventData function inside it to get the detailed information for the received device event.

To get the CAP_DEVICEEVENT capability values, call L_TwainGetDeviceEventCapability function.

To set the CAP_DEVICEEVENT capability value, call L_TwainSetDeviceEventCapability function.

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_TwainSetDeviceEventCallback, L_TwainGetDeviceEventData, L_TwainSetDeviceEventCapability, L_TwainGetDeviceEventCapability, L_TwainResetDeviceEventCapability
Topics:	Getting and Setting Capabilities
	TWAIN Functionality: Callback