IOleInPlaceSiteWindowless interface

Extends the IOleInPlaceSiteEx interface. IOleInPlaceSiteWindowless works with IOleInPlaceObjectWindowless which is implemented on the windowless object. Together, these two interfaces provide services to a windowless object from its container allowing the windowless object to:

  • Process window messages
  • Participate in drag and drop operations
  • Perform drawing operations
Having a window can place unnecessary burdens on small objects, such as controls. It prevents an object from being non-rectangular. It prevents windows from being transparent. It prevents the small instance size needed by many small controls.

A windowless object can enter the in-place active state without requiring a window or the resources associated with a window. Instead, the object's container provides the object with many of the services associated with having a window.


The IOleInPlaceSiteWindowless interface has these methods.

Method Description
IOleInPlaceSiteWindowless::AdjustRect Adjusts a specified rectangle if it is entirely or partially covered by overlapping, opaque objects.
IOleInPlaceSiteWindowless::CanWindowlessActivate Informs an object if its container can support it as a windowless object that can be in-place activated.
IOleInPlaceSiteWindowless::GetCapture Called by an in-place active, windowless object to determine whether it still has the mouse capture.
IOleInPlaceSiteWindowless::GetDC Provides an object with a handle to a device context for a screen or compatible device from its container.
IOleInPlaceSiteWindowless::GetFocus Called by an in-place active, windowless object to determine whether it still has the keyboard focus.
IOleInPlaceSiteWindowless::InvalidateRect Enables an object to invalidate a specified rectangle of its in-place image on the screen.
IOleInPlaceSiteWindowless::InvalidateRgn Enables an object to invalidate a specified region of its in-place image on the screen.
IOleInPlaceSiteWindowless::OnDefWindowMessage Invokes the default processing for all messages passed to an object.
IOleInPlaceSiteWindowless::ReleaseDC Releases the device context previously obtained by a call to IOleInPlaceSiteWindowless::GetDC.
IOleInPlaceSiteWindowless::ScrollRect Enables an object to scroll an area within its in-place active image on the screen.
IOleInPlaceSiteWindowless::SetCapture Enables an in-place active, windowless object to capture all mouse messages.
IOleInPlaceSiteWindowless::SetFocus Sets the keyboard focus for a UI-active, windowless object.


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