LTWAINCAPABILITYCALLBACK Function

#include "lttwn.h"

L_INT pEXT_CALLBACK YourFunction (hSession, uCap, pCapabiltiy, pUserData)

HTWAINSESSION hSession;

handle to an existing TWAIN session

L_UINT uCap;

capability received

pTW_CAPABILITY * pCapability;

pointer to a structure

L_VOID * pUserData;

pointer to additional parameters

Called for each capability enumerated by the L_TwainEnumCapabilities function. The address of this callback is passed as an argument in L_TwainEnumCapabilities.

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 enumerated. For more information on capability values, refer to the Twain 1.9 Specification, available at www.twain.org.

pCapability

Pointer to the TW_CAPABILITY structure that references the capability data being enumerated. For more information about TW_CAPABILITY, refer to the TWAIN 1.9 specification from the site http://www.twain.org/.

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_TwainEnumCapabilities.)

 

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

To prevent memory leaks, the user should free the pointer to TW_CAPABILITY structure within the callback 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_TwainEnumCapabilities.

Topics:

TWAIN Functionality: Callback Functions.

Example

For an example, refer to L_TwainStartCapsNeg.

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