IOverlayNotify::OnPositionChange method (strmif.h)

Article
02/22/2024

[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

The OnPositionChange method provides notification that the position has changed.

Syntax

HRESULT OnPositionChange(
  [in] const RECT *pSourceRect,
  [in] const RECT *pDestinationRect
);

Parameters

[in] pSourceRect

Pointer to the source video rectangle.

[in] pDestinationRect

Pointer to the destination video rectangle. Note that this is not clipped to the visible display area.

Return value

Returns S_OK if successful. If the method fails, it returns an HRESULT error code.

Remarks

This method is a callback intended for use by hardware overlay cards that do not want the expense of synchronous clipping updates, and just want to know when the source or destination video positions change.

Unlike the IOverlayNotify::OnClipChange method, this method is not called in synchronization with the window changing but, rather, at some point after the window has changed (basically in time with WM_SIZE messages received). This is therefore suitable for overlay cards that do not inlay their data to the frame buffer.

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	strmif.h (include Dshow.h)
Library	Strmiids.lib