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# OnReadPage Method of the IImageViewerEvents Interface

> OnReadPage method of the IImageViewerEvents Interface in ABBYY FineReader Engine Visual Components on Windows — This method is implemented on the client-side.

This method is implemented on the client-side. It is called by ABBYY FineReader Engine before the start of the page recognition process which has been invoked from [Image Viewer](/fine-reader/engine/visual-components-reference/imageviewer) by calling the [MI\_Read](/fine-reader/engine/visual-components-reference/imageviewer/image-viewer-commands#mi_read) command. For the ways how this command can be called see the [Image Viewer Commands](/fine-reader/engine/visual-components-reference/imageviewer/image-viewer-commands) list.

The method informs the client that an active page is going to be recognized. With the help of this method it is possible to cancel the operation.

## Syntax

### C++

```cpp theme={null}
HRESULT OnReadPage( VARIANT_BOOL* Cancel );
```

### C\#

```csharp theme={null}
void OnReadPage( out bool Cancel );
```

### Visual Basic .NET

```vb theme={null}
Sub OnReadPage(ByRef Cancel As Boolean)
```

## Parameters

Cancel

\[out] You may set this variable to TRUE to indicate that the process should be terminated. In this case, page recognition will not be performed.

## Return values

\[C++ only] If this method returns a value other than S\_OK, it indicates that an error occurred on the client-side, and in this case the value of the Cancel parameter is not taken into account.

## Remarks

The client implementation of this method must assure that all exceptions thrown inside the method are caught and handled and no exceptions are propagated outside the method. Propagation of an exception outside the method may lead to unpredictable results (such as program termination).

## See also

[IImageViewerEvents](/fine-reader/engine/visual-components-reference/iimageviewerevents)

[OnReadBlocks](/fine-reader/engine/visual-components-reference/iimageviewerevents/onreadblocks-method)