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86 lines
4.0 KiB
86 lines
4.0 KiB
4 months ago
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Implementation Details for SdkControllerApp
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---- 2012-03-22
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App is in the namespace com.android.tools.sdkcontroller.
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This is an app that has a minSdkVersion of 7 (Eclair)
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and a targetSdkVersion of 15 (ICS). The target version
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means the app is forbidden under ICS from doing any network
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communication on its main thread.
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The overall design:
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- A background service is started by the app. It handles the connection
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to the emulator and provides a number of "handlers". Handlers can be
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though as being separate tasks that the user wants to achieve, for example
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sending sensor data, sending multi-touch events, receiving screen updates,
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sending a camera feed, etc.
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- All the handlers are started when the service starts and shutdown with it.
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They basically stay there as long as the app is running, and its up to the
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handler to deal with emulator connections starts/stopping. Some handlers
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will run in the background (e.g. sending sensor data) whereas other might
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need an activity to connect to them first.
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- The app has a number of activities which connect to existing handlers.
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Another way to see it is that the app handles a number of tasks which are
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composed of a background handler (that consumes data form the emulator and
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can send data to the emulator) and an optional activity for UI (that displays
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or controls the handler's state.)
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Here's a quick overview of the classes in the application:
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The main UI is in activities.MainActivity.
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There are 2 tasks activities: SensorActivity and MultiTouchActivity.
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These all derive from BaseBindingActivity which provides a few convenient common features
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- in onResume this will bind to the service, creating and starting it if necessary.
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- in onPause, this will unbind from the service, but does not stop it.
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Note however that due to the asynchronous nature of the bind operation, the activity
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must not attempt to use the service from onResume. Instead there are 2 callbacks to use:
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- onServiceConnected when the bind succeeded.
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- onServiceDisconnected as the reverse operation.
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When the activity is connected to the service, it can then use getServiceBinder()
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to get an interface to talk to the service.
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In the other direction, the activity provides a listener for the service to notify
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the application: ControllerListener createControllerListener().
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The activity can then access the handler:
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handler = getServiceBinder().getHandler(HandlerType....)
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and then the activity wants to provide a listener to get notified by the handler:
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handler.addUiHandler(new android.os.Handler(this));
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The emulator connection is separated in the "lib" subpackage:
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- EmulatorConnection abstracts a connection to the emulator.
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- Object is first created by giving a non-null EmulatorListener.
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- then connect(port) is called to initiate the connection.
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- The EmulatorConnection is always created in SYNC mode.
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- EmulatorListener is a callback: the emulator connection uses it to indicate
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when the connection is actually connected or disconnected.
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In the end we have the following workflow describing who controls what (-->):
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Emulator
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^ ^
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| | EmuCnxHandler
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sendEventToEmulator| | (EmulatorListener)
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| +-------------+
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handlers.BaseHandler | v
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Activity ------------------------> Handler <---- ControllerService
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UI <------------------------ | ^
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android.os.Handler | |
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| ^ | |
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| | ControllerListener | |
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| +--------------------------------------------------+ |
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+-----------------------------------------------------------+
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ControllerBinder
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----
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