MATLAB IMAGE ACQUISITION TOOLBOX - RELEASE NOTES Guide de l'utilisateur télécharger pdf (Page 122)

6 Defining Device-Specific Properties

6-10

Implementing Get and Set Support for Device-Specific Properties

After connecting to a device through your adaptor, users might want to view or modify

values of the properties of the device. For example, a user might adjust the value of the

Brightness property or retrieve the current value of the Temperature property. (For

information about how to define the properties you want to expose to users, see “Creating

Device Properties” on page 6-5.)

To receive notification from the engine when a user wants to view or modify a property,

associate a listener object with the property. The toolbox defines two types of listener

classes: get listeners that respond to get commands and set listeners that respond to set

commands.

To provide support for getting and setting property values, follow this procedure:

Define a listener class of the appropriate type. The toolbox defines two abstract

classes, one for get listeners and one for set listeners, from which you derive your

class.

Implement the virtual function required by the class.

Associate an instance of your listener class with the property.

The following sections describe how to set up get listeners and set listeners and in your

adaptor.

Setting Up Get Listeners in Your Adaptor

To receive notification from the engine when a user requests the current value of a

property using the get command:

Define a get listener class, deriving it from the IPropCustomGetFcn abstract class

—see “Defining a Get Listener Class” on page 6-10.

Implement the getValue() virtual function in your listener class—see “Creating

the getValue() Function for Your Class” on page 6-11.

Associate an instance of your listener class with a property—see “Associating Get

Listeners with Properties” on page 6-13.

Defining a Get Listener Class

Create a get listener class, deriving it from the abstract class IPropCustomGetFcn, as

shown in the following example.

1 2 ... 117 118 119 120 121 122 123 124 125 126 127 ... 171 172

Pas de commentaire

MATLAB IMAGE ACQUISITION TOOLBOX - RELEASE NOTES Guide de l'utilisateur Page 122