Using the event manager API

Operation and semantics overview

To open an event queue, a process makes a library call. The process must indicate the classes (types) of devices it wants to use. Common classes for devices include ``relative locator'' devices (mice) or ``absolute locator'' devices (bitpads). The event manager interface then checks the configuration files to determine what physical devices are allowed to give input to the process's terminal. The devices listed in the configuration file are ``associated'' with that terminal. Associated devices of the proper class are opened for events with the initial call from the process. When a device is opened for events, data from the device is translated to events, and entered into the process's event queue.

An event device is associated with some terminals or console multi-screens. When using an event device with the console, it should be associated with each multiscreen. In order for an application to use event devices, the devices must be associated with the terminal that invoked the application. It is possible for programs that are not running on any terminal to use the mouse, but they cannot use the event manager API.

An event device is said to be ``attached'' to an event queue if the device has been opened and input from the device is being received by the event queue. Note that an application can choose whether or not to attach any associated event device to its event queue while it is running. For example, if both a bitpad and a mouse are associated with a terminal, it is possible for the application to open only the mouse for input, and then close the mouse and open the bitpad without exiting.

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© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003