GrabberListener

The GrabberListener class is the base class for all classes implementing a callback handler. A callback handler class has to be derived from GrabberListener and has to overwrite one or more callback methods. Every instance of a callback handler class has to be registered in Grabber by a call to Grabber::addListener. The available methods are:

The GrabberListener::overlayCallback method. It is called directly after the video capture device has delivered a new frame. Applications use this method to draw on the live video. It is called before the GrabberListener::frameReady method is called.
The GrabberListener::frameReady method. It is called after a frame has been copied into a memory buffer. Graphics and text that have been drawn in the GrabberListener::overlayCallback method are visible in the memory buffer when this method is called. Applications may use this method for image processing, because direct access to the image data is provided in this callback method.
The GrabberListener::deviceLost method. It is called, when the video capture device is no more available, i.e. it was unplugged.

Information

Header File: tisudshl.h
Namespace: DShowLib

Methods

	Method		Description


	deviceLost		This method is called when the video capture device is lost, i.e. unplugged.

	frameReady		This method is called after the video capture device has copied a new frame into a memory buffer.

	overlayCallback		This method is called after the video capture device has delivered a new frame and allows modifications to the OverlayBitmap.

Enumerations

	Enumeration		Description


	tListenerType		tListenerType enumerates the callback types supported by the Grabber.

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