| # Chrome OS Power Manager Input |
| |
| powerd uses user input to determine when the system should turn its backlight |
| off or suspend in response to inactivity. powerd does not listen for this input |
| directly; rather, it receives periodic `HandleUserActivity` D-Bus method calls |
| from Chrome while the user is active. These method calls include a |
| [UserActivityType] enum describing the type of activity that was observed, |
| allowing powerd to e.g. avoid turning the screen back on if the user presses the |
| Brightness Down key while the screen is already off. |
| |
| [`powerd/system/input_watcher.cc`] uses the kernel's input subsystem to observe |
| power button and lid switch events. (ACPI power button events may be |
| additionally received by Chrome as standard keyboard input, but they are |
| ignored there since button releases are not reported correctly.) These events |
| are reported to Chrome via `InputEvent` D-Bus signals containing [InputEvent] |
| protocol buffers; Chrome uses the power button notifications to display |
| screen-lock and shutdown animations. |
| |
| See the [Power Buttons] document for more information about power button |
| behavior. |
| |
| [UserActivityType]: ../../system_api/dbus/power_manager/dbus-constants.h |
| [`powerd/system/input_watcher.cc`]: ../powerd/system/input_watcher.cc |
| [InputEvent]: ../../system_api/dbus/power_manager/input_event.proto |
| [Power Buttons]: power_buttons.md |
