OnMouseWheel Method of the IInputEvents Interface

This method is implemented on the client-side. It is called by ABBYY FineReader Engine when the mouse wheel moves while Image Viewer, Zoom Viewer, Text Editor, Text Validator, or Document Viewer has focus.

It delivers to the client information on the coordinates of the mouse pointer, the amount the mouse wheel has been moved, and modification keys has been used.



HRESULT OnMouseWheel(
  int Flags,
  int ZDelta,
  int X,
  int Y


void OnMouseWheel(
  int Flags,
  int ZDelta,
  int X,
  int Y

Visual Basic .NET

Sub OnMouseWheel( _
  Flags As Integer, _
  ZDelta As Integer, _
  X As Integer, _
  Y As Integer _


[in] Indicates whether various virtual keys are down. This parameter can be any combination of the following values:
  • MK_CONTROL (0x0008), if Ctrl key is down.
  • MK_LBUTTON (0x0001), if left mouse button is down.
  • MK_MBUTTON (0x0010), if middle mouse button is down.
  • MK_RBUTTON (0x0002), if right mouse button is down.
  • MK_SHIFT (0x0004), if Shift key is down.

The constants are defined in Winuser.h.

[in] Indicates the amount the mouse wheel has been moved. This is a signed count of the number of detents the mouse wheel has rotated. A detent is one notch of the mouse wheel.
[in] Specifies the horizontal coordinate of the mouse pointer in screen coordinates.
[in] Specifies the vertical coordinate of the mouse pointer in screen coordinates.

Return values

This method has no specific return values. It returns the standard return values of ABBYY FineReader Engine functions.


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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