Edit

IOleInPlaceObjectWindowless::OnWindowMessage method (ocidl.h)

  • Article

Dispatches a message from a container to a windowless object that is in-place active.

Syntax

HRESULT OnWindowMessage(
  [in]  UINT    msg,
  [in]  WPARAM  wParam,
  [in]  LPARAM  lParam,
  [out] LRESULT *plResult
);

Parameters

[in] msg

The identifier for the window message provided to the container by Windows.

[in] wParam

A parameter for the window message provided to the container by Windows.

[in] lParam

A parameter for the window message provided to the container by Windows.

[out] plResult

A pointer to result code for the window message.

Return value

This method returns S_OK on success. Other possible return values include the following.

Return code Description
S_FALSE
 The windowless object did not process the window message. The container should call the DefWindowProc for the message or process the message itself as described below.

Remarks

A container calls this method to send window messages to a windowless object that is in-place active. The container should dispatch messages according to the following guidelines:

For the following messages, the container should first dispatch the message to the windowless object that has captured the mouse, if any. Otherwise, the container should dispatch the message to the windowless object under the mouse cursor. If there is no such object, the container is free to process the following messages for itself:

  • WM_MOUSEMOVE
  • WM_SETCURSOR
  • WM_XBUTTONDOWN
  • WM_XBUTTONUP
  • WM_XBUTTONDBLCLK
The container should dispatch the message to the windowless object with the keyboard focus for the following messages:
  • WM_CANCELMODE
  • WM_CHAR
  • WM_DEADCHAR
  • WM_HELP
  • WM_IMExxx
  • WM_KEYDOWN
  • WM_KEYUP
  • WM_SYSDEADCHAR
  • WM_SYSKEYDOWN
  • WM_SYSKEYUP
For all other messages, the container should process the message on its own.

The windowless object can return S_FALSE to this method to indicate that it did not process the message. Then, the container either performs the default behavior for the message by calling the DefWindowProc function, or processes the message itself.

The container must pass the following window messages to the default window procedure:

  • WM_CHAR
  • WM_DEADCHAR
  • WM_IMExxx
  • WM_KEYDOWN
  • WM_KEYUP
  • WM_MOUSEMOVE
  • WM_SYSCHAR
  • WM_SYSDEADCHAR
  • WM_SYSKEYUP
  • WM_XBUTTONDOWN
  • WM_XBUTTONUP
  • WM_XBUTTONDBLCLK
The container must process the following window messages as its own:
  • WM_CONTEXTMENU
  • WM_HELP
  • WM_SETCURSOR
Note  For WM_SETCURSOR, the container can either set the cursor itself or do nothing.
 
Objects can also use IOleInPlaceSiteWindowless::OnDefWindowMessage to explicitly invoke the default message processing from the container. In the case of the WM_SETCURSOR message, this allows an object to take action if the container does not set the cursor.

All coordinates passed to the object in wParam and lParam are specified as client coordinates of the containing window.

Requirements

Requirement Value
Minimum supported client Windows 2000 Professional [desktop apps only]
Minimum supported server Windows 2000 Server [desktop apps only]
Target Platform Windows
Header ocidl.h

See also