L_INT pEXT_CALLBACK YourFunction(ulType, rcBarLocation, pszBarCodeData, pUserData)

L_UINT32 ulType;

type of the decoded barcode

RECT rcBarLocation;

location of the decoded barcode

L_CHAR * pszBarCodeData;

string of the decoded barcode

L_VOID * pUserData;

pointer to additional parameters

Occurs when the reading process has successfully decoded a barcode symbology



ulType Barcode type.
rcBarLocation The barcode location on the bitmap.
pszBarCodeData Pointer to the barcode data string.
pUserData Void pointer that you can use to pass one or more additional parameters that the help callback function needs.

To use this feature, assign a value to a variable or create a structure that contains as many fields as you need. Then, in this parameter, pass the address of the variable or structure, casting it to L_VOID *. The callback function, which receives the address in its own pUserData parameter, can cast it to a pointer of the appropriate data type to access your variable or structure.

If the additional parameters are not needed, you can pass NULL in this parameter.


SUCCESS Continue the process.
ERROR_USER_ABORT Abort the process.


Use this callback function to get the decoded barcode before finishing the processing of the entire input document.

Help Version 20.0.2018.2.22
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LEADTOOLS Barcode C++ Class Library Help