OnReadBlocks Method of the IZoomViewerEvents Interface

This method is implemented on the client-side. It is called by ABBYY FineReader Engine before the start of the blocks recognition process which has been invoked from Zoom Viewer in one of the following ways:

  • Read Area item in the context menu is selected
  • Ctrl+Shift+B hot key is pressed
  • MI_ReadBlock command is called using the DoCommand method of the IZoomViewer::Commands

The method delivers to the client the indices of blocks which are going to be recognized. With the help of this method it is possible to cancel the operation.



HRESULT OnReadBlocks(
  IIntsCollection*  BlocksIndices,
  VARIANT_BOOL*     Cancel


void OnReadBlocks(
  IIntsCollection BlocksIndices,
  out bool       Cancel

Visual Basic .NET

Sub OnReadBlocks( _
  BlocksIndices As IIntsCollection, _
  ByRef Cancel As Boolean _


[in] Contains indices of the blocks which are going to be recognized as an IntsCollection object.
[out] You may set this variable to TRUE to indicate that the process should be terminated. In this case, 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.


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



24.03.2023 8:51:52

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