> ## Documentation Index
> Fetch the complete documentation index at: https://docs.abbyy.com/llms.txt
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# IScanCallback Interface

<Note>
  This interface is implemented in FRE for Windows.
</Note>

This is a callback interface that is used for managing scanning operations. This interface is implemented on the client-side.

An object receiving notifications through this interface's methods may do the following inside the methods' implementation:

* Report errors which occurred during scanning to the user.

* Cancel processing.

* Process any system messages to help prevent the application from appearing unresponsive during long operations. This can be helpful in applications with a user interface.

## Methods

| Name                                                                                                      | Description                                                                                               |
| --------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------- |
| [OnError](/fine-reader/engine/api-reference/mechanism-objects/iscancallback/onerror-method)               | Delivers to the client information about the errors that occurred during scanning.                        |
| [OnImageScanned](/fine-reader/engine/api-reference/mechanism-objects/iscancallback/onimagescanned-method) | Delivers information about the course of the scanning operation and allows it to be stopped if necessary. |
| [OnScanComplete](/fine-reader/engine/api-reference/mechanism-objects/iscancallback/onscancomplete-method) | Gives notification that the scanning operation has been completed.                                        |

## Input parameter

This object is passed as an input parameter to the following methods:

* [Scan](/fine-reader/engine/api-reference/mechanism-objects/scansource/scan-method) and [BeginScan](/fine-reader/engine/api-reference/mechanism-objects/scansource/beginscan-method) methods of the [ScanSource](/fine-reader/engine/api-reference/mechanism-objects/scansource) object.

## Samples

This object is used in the following code samples: [Scanning](/fine-reader/engine/guided-tour/samples#scanning).

## See also

[ScanManager](/fine-reader/engine/api-reference/mechanism-objects/scanmanager)