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