References ▼
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.
#include "lttwn.h"
L_INT pEXT_CALLBACK YourFunction (hSession, pUserData);
Handle to an existing TWAIN session. This handle is obtained by calling the L_TwainInitSession or L_TwainInitSession2 or L_TwainInitSession2 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_TwainSetDeviceEventCallback.)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. |
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.
For an example, refer to L_TwainGetDeviceEventData.