System Power State Transitions
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4/8/2010
Power Manager makes system power state transitions under the following circumstances:
- An OEM-specific event that requires a state change.
- An application calls the SetSystemPowerState function.
OEM-specific events might include going from AC power to battery power, prolonged periods of system inactivity, insertion into a cradle, low battery levels, and so on. The OEM is responsible for customizing Power Manager to recognize when transitions between system power states are appropriate and for carrying them out when necessary. The base power management sources included with Platform Builder recognize AC-to-battery power transitions.
Applications can call SetSystemPowerState with an explicit power state name or a predefined system power state constant. Applications that have the OEM-specific system power states can use explicit power state names. Platform-independent applications generally set POWER_STATE_XXX flags instead, and allow Power Manager to determine which OEM-specific power state fits best. Power Manager can restrict the states that applications can request.