References ▼
Called for each image being acquired from the TWAIN source to the application. The address of this callback is passed as an argument in L_TwainAcquire.
#include "lttwn.h"
L_INT pEXT_CALLBACK YourFunction (hSession, pBitmap, pUserData)
Handle to an existing TWAIN session. This handle is obtained by calling the L_TwainInitSession or L_TwainInitSession2 function.
Pointer to the bitmap handle that references the bitmap acquired from the TWAIN source. It is the same bitmap handle that you specify when calling the L_TwainAcquire function.
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_TwainAcquire.)
Keep in mind that this is a void pointer, which must be cast to the appropriate data type within your callback function.
| Value | Meaning |
|---|---|
| SUCCESS | The function was successful. |
| < 1 | An error occurred. Refer to Return Codes. |
To prevent memory leaks, the user should free the bitmap within the callback function.
The L_TwainGetExtendedImageInfo function can only be called within the callback.
For an example, refer to L_TwainAcquire.