IOleInPlaceObject

IOleInPlaceObject is a core COM interface in Microsoft's Component Object Model architecture. It defines methods that an embedded object can use to interact with its container when it is actively displayed on screen. This interface is essential for in-place activation, a feature that allows an embedded object to take over part of the container's user interface, such as menus and toolbars, when it is being edited or manipulated.

Objects that implement IOleInPlaceObject are typically OLE (Object Linking and Embedding) server objects that support in-place editing. The container calls methods on this interface to inform the object about changes in its environment, such as resizing, scrolling, or deactivation. The object, in turn, uses these methods to manage its own display and interaction within the container's window.

Key methods include OnFrameWindowActivate, which notifies the object when the container's top-level window is activated or deactivated, and OnDocWindowActivate, which signals activation/deactivation of the container's document window. Another important method is ResizeBorder, which allows the container to inform the object about changes to the border area of its window, enabling the object to adjust its content accordingly. Finally, GetWindowContext provides the object with information about its surrounding window, such as the handle of the container's window and the rectangle defining its position. Through these methods, IOleInPlaceObject facilitates a seamless and integrated user experience for embedded objects.