Defining Your Adaptor Class
The next four topics describe how to define your adaptor class and instantiate an object
of this class. Every adaptor must define a class that is a subclass of the adaptor kit
IAdaptor abstract class. This abstract class defines several virtual
functions that your adaptor class must implement. The next four topics get you started with
an adaptor class implementation by creating a stub implementation. This stub implementation
will enable you to create a video input object with your adaptor using the
videoinput function. In subsequent topics, you complete adaptor
development by fleshing out the implementations of these virtual functions.
When a user calls the
videoinput function to create a video input
object, the toolbox engine calls two of the exported functions in your adaptor:
(To see a flow-of-control diagram that shows how these functions fit with the other required exported functions, see Using Adaptor Exported Functions.)
getDeviceAttributes() function defines which properties of the
device that you want to expose to users. This function is described only briefly in this
chapter (see Identifying Video Sources). For complete information
about implementing this exported function, see Defining Device-Specific Properties.
The toolbox engine calls your adaptor's
createInstance() function to
instantiate an object of the adaptor class. Every adaptor must define a class that is a
subclass of the
IAdaptor abstract class, providing implementations of
the pure virtual functions defined in this abstract class.
This chapter describes how to create a stub implementation of your adaptor class (see Creating Stub Implementation of Your Adaptor Class) and create the constructor and destructor for this class, see Instantiating an Adaptor Object. In Acquiring Image Data you flesh out the implementation of these functions.
Because each instance of your adaptor class is associated with a specific format selected by the user, most of the information returned by these functions is static.