| # SystemUI |
| |
| “Everything you see in Android that's not an app” |
| |
| SystemUI is a persistent process that provides UI for the system but outside |
| of the system_server process. |
| |
| The starting point for most of sysui code is a list of services that extend |
| SystemUI that are started up by SystemUIApplication. These services then depend |
| on some custom dependency injection provided by Dependency. |
| |
| Inputs directed at sysui (as opposed to general listeners) generally come in |
| through IStatusBar. Outputs from sysui are through a variety of private APIs to |
| the android platform all over. |
| |
| ## SystemUIApplication |
| |
| When SystemUIApplication starts up, it will start up the services listed in |
| config_systemUIServiceComponents or config_systemUIServiceComponentsPerUser. |
| |
| Each of these services extend SystemUI. SystemUI provides them with a Context |
| and gives them callbacks for onConfigurationChanged (this historically was |
| the main path for onConfigurationChanged, now also happens through |
| ConfigurationController). They also receive a callback for onBootCompleted |
| since these objects may be started before the device has finished booting. |
| |
| Each SystemUI service is expected to be a major part of system ui and the |
| goal is to minimize communication between them. So in general they should be |
| relatively silo'd. |
| |
| ## Dependencies |
| |
| The first SystemUI service that is started should always be Dependency. |
| Dependency provides a static method for getting a hold of dependencies that |
| have a lifecycle that spans sysui. Dependency has code for how to create all |
| dependencies manually added. SystemUIFactory is also capable of |
| adding/replacing these dependencies. |
| |
| Dependencies are lazily initialized, so if a Dependency is never referenced at |
| runtime, it will never be created. |
| |
| If an instantiated dependency implements Dumpable it will be included in dumps |
| of sysui (and bug reports), allowing it to include current state information. |
| This is how \*Controllers dump state to bug reports. |
| |
| If an instantiated dependency implements ConfigurationChangeReceiver it will |
| receive onConfigurationChange callbacks when the configuration changes. |
| |
| ## IStatusBar |
| |
| CommandQueue is the object that receives all of the incoming events from the |
| system_server. It extends IStatusBar and dispatches those callbacks back any |
| number of listeners. The system_server gets a hold of the IStatusBar when |
| StatusBar calls IStatusBarService#registerStatusBar, so if StatusBar is not |
| included in the XML service list, it will not be registered with the OS. |
| |
| CommandQueue posts all incoming callbacks to a handler and then dispatches |
| those messages to each callback that is currently registered. CommandQueue |
| also tracks the current value of disable flags and will call #disable |
| immediately for any callbacks added. |
| |
| There are a few places where CommandQueue is used as a bus to communicate |
| across sysui. Such as when StatusBar calls CommandQueue#recomputeDisableFlags. |
| This is generally used a shortcut to directly trigger CommandQueue rather than |
| calling StatusManager and waiting for the call to come back to IStatusBar. |
| |
| ## Default SystemUI services list |
| |
| ### [com.android.systemui.Dependency](/packages/SystemUI/src/com/android/systemui/Dependency.java) |
| |
| Provides custom dependency injection. |
| |
| ### [com.android.systemui.util.NotificationChannels](/packages/SystemUI/src/com/android/systemui/util/NotificationChannels.java) |
| |
| Creates/initializes the channels sysui uses when posting notifications. |
| |
| ### [com.android.systemui.keyguard.KeyguardViewMediator](/packages/SystemUI/src/com/android/systemui/keyguard/KeyguardViewMediator.java) |
| |
| Manages keyguard view state. |
| |
| ### [com.android.systemui.recents.Recents](/packages/SystemUI/src/com/android/systemui/recents/Recents.java) |
| |
| Recents tracks all the data needed for recents and starts/stops the recents |
| activity. It provides this cached data to RecentsActivity when it is started. |
| |
| ### [com.android.systemui.volume.VolumeUI](/packages/SystemUI/src/com/android/systemui/volume/VolumeUI.java) |
| |
| Registers all the callbacks/listeners required to show the Volume dialog when |
| it should be shown. |
| |
| ### [com.android.systemui.status.phone.StatusBar](/packages/SystemUI/src/com/android/systemui/status/phone/StatusBar.java) |
| |
| This shows the UI for the status bar and the notification shade it contains. |
| It also contains a significant amount of other UI that interacts with these |
| surfaces (keyguard, AOD, etc.). StatusBar also contains a notification listener |
| to receive notification callbacks. |
| |
| ### [com.android.systemui.usb.StorageNotification](/packages/SystemUI/src/com/android/systemui/usb/StorageNotification.java) |
| |
| Tracks USB status and sends notifications for it. |
| |
| ### [com.android.systemui.power.PowerUI](/packages/SystemUI/src/com/android/systemui/power/PowerUI.java) |
| |
| Tracks power status and sends notifications for low battery/power saver. |
| |
| ### [com.android.systemui.media.RingtonePlayer](/packages/SystemUI/src/com/android/systemui/media/RingtonePlayer.java) |
| |
| Plays ringtones. |
| |
| ### [com.android.systemui.keyboard.KeyboardUI](/packages/SystemUI/src/com/android/systemui/keyboard/KeyboardUI.java) |
| |
| Shows UI for keyboard shortcuts (triggered by keyboard shortcut). |
| |
| ### [com.android.systemui.shortcut.ShortcutKeyDispatcher](/packages/SystemUI/src/com/android/systemui/shortcut/ShortcutKeyDispatcher.java) |
| |
| Dispatches shortcut to System UI components. |
| |
| ### @string/config_systemUIVendorServiceComponent |
| |
| Component allowing the vendor/OEM to inject a custom component. |
| |
| ### [com.android.systemui.util.leak.GarbageMonitor$Service](/packages/SystemUI/src/com/android/systemui/util/leak/GarbageMonitor.java) |
| |
| Tracks large objects in sysui to see if there are leaks. |
| |
| ### [com.android.systemui.LatencyTester](/packages/SystemUI/src/com/android/systemui/LatencyTester.java) |
| |
| Class that only runs on debuggable builds that listens to broadcasts that |
| simulate actions in the system that are used for testing the latency. |
| |
| ### [com.android.systemui.globalactions.GlobalActionsComponent](/packages/SystemUI/src/com/android/systemui/globalactions/GlobalActionsComponent.java) |
| |
| Shows the global actions dialog (long-press power). |
| |
| ### [com.android.systemui.ScreenDecorations](/packages/SystemUI/src/com/android/systemui/ScreenDecorations.java) |
| |
| Draws decorations about the screen in software (e.g. rounded corners, cutouts). |
| |
| ### [com.android.systemui.biometrics.BiometricDialogImpl](/packages/SystemUI/src/com/android/systemui/biometrics/BiometricDialogImpl.java) |
| |
| Biometric UI. |
| |
| ### [com.android.systemui.wmshell.WMShell](/packages/SystemUI/src/com/android/systemui/wmshell/WMShell.java) |
| |
| Delegates SysUI events to WM Shell controllers. |
| |
| --- |
| |
| * [Plugins](/packages/SystemUI/docs/plugins.md) |
| * [Demo Mode](/packages/SystemUI/docs/demo_mode.md) |
