| Available in LEADTOOLS Imaging Pro, Vector, Document, and Medical Imaging toolkits. | 
L_TwainSetDeviceEventCallback
#include "lttwn.h"
L_LTTWN_API L_INT L_TwainSetDeviceEventCallback(hSession, pfnCallBack, pUserData)
| HTWAINSESSION hSession; | /* handle to an existing TWAIN session */ | 
| LTWAINDEVICEEVENTCALLBACK pfnCallBack; | /* callback function */ | 
| L_VOID * pUserData; | /* pointer to more parameters for the callback */ | 
Sets the device event callback.
| Parameter | Description | 
| hSession | Handle to an existing TWAIN session. This handle is obtained by calling the L_TwainInitSession function. | 
| pfnCallBack | Pointer to a callback function. The callback function must adhere to the function syntax specified in LTWAINDEVICEEVENTCALLBACK 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
This function should be called after calling L_TwainStartCapsNeg function and before calling L_TwainEndCapsNeg 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. | 
See Also
| Functions: | L_TwainStartCapsNeg, L_TwainGetDeviceEventData, L_TwainSetDeviceEventCapability, L_TwainGetDeviceEventCapability, L_TwainResetDeviceEventCapability, LTWAINDEVICEEVENTCALLBACK | 
| Topics: | |
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Example
For an example, refer to L_TwainGetDeviceEventData.