Apple Newton Utilities Guide de l'utilisateur télécharger pdf (Page 623)

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CHAPTER 17

Additional System Services

Using Additional System Services 17-7

Power Registry 17

The Power Registry implements a cooperative model for powering the Newton on

and off. When power is turned on or off, this service

■ notiﬁes registered applications of the impending change in power status

■ allows applications to temporarily halt the shutdown process

■ executes registered callback functions

The Power Registry model is based on the registration of callback functions to

execute when the Newton is powered on or off. You can use the

RegPowerOn

function to register a callback function for execution when the Newton is powered

on. The

UnRegPowerOn function reverses the action of the RegPowerOn

function; that is, it removes the speciﬁed function from the registry of functions

called when the Newton is powered on.

Power-on functions can also be tied to the login screen. The login screen appears

when the user powers on a Newton device. Password-protected Newton devices

display the login screen until the password is correctly entered. If your power-on

function has a visible component, you should tie this function into the login screen,

instead of as a regular power-on function. The

RegLogin and UnRegLogin

methods are used to register and unregister login functions respectively.

You can use the

RegPowerOff function to register a callback function for

execution when the Newton is powered off. The

UnRegPowerOff function

removes the speciﬁed function from the registry of functions called when the

Newton is powered off.

Note that “power-off” callback functions can delay an impending shutdown when

necessary. For example, your callback function might delay an impending power-

off operation until it can successfully tear down a communications endpoint.

Power Compatibility Information 17

Applications can now register callback functions to execute when the Newton

powers on or off. All of the functions that provide this service are new.

The

BatteryLevel function is obsolete. It has been replaced by the

BatteryStatus function.

Using Additional System Services 17

This section discusses how to use the undo, idler objects, alerts and alarms, change

notiﬁcation, progress reporting, and power registry services.

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Apple Newton Utilities Guide de l'utilisateur Page 623

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