Processing and Analysis of buttons such as android4.0 Power, home, and menu

I. Processing of Power, Home, Menu, back, Vol +, Vol-

We know that when WindowManagerService is created, an InputManager instance is declared. This InputManager adds mCallbacks and logoff to C ++ through NativeInit to create InputDispatcher and InputReader. Add the two instances to InputDispatcherThread and InputReaderThread to read and dispatch input events.

1. InputManager. java:

Constructor has the following implementation:

This. mCallbacks = new Callbacks ();

This is critical. It is the method for implementing callback in the C ++ layer. Then add it to C ++ through NativeInit.

Private final class Callbacks {

Public int interceptKeyBeforeQueueing (KeyEvent event, int policyFlags, boolean

IsScreenOn ){

Return mWindowManagerService. mInputMonitor. interceptKeyBeforeQueueing (

Event, policyFlags, isScreenOn );

}

Public int interceptMotionBeforeQueueingWhenScreenOff (int policyFlags ){

Return mWindowManagerService. mInputMonitor.

InterceptMotionBeforeQueueingWhenScreenOff (policyFlags );

}

......

}

All of these functions call mPolicy through WindowManagerService to implement specific functions.

2. com_android_server_InputManager.cpp

The following operations are performed in the android_server_InputManager_nativeInit function:

GNativeInputManager = new NativeInputManager (contextObj, callbacksObj, lobj );

Here, the callbacks implemented in InputManager. java is added to mCallbacksObj in NativeInputManager.

Build InputManager at the same time: mInputManager = new InputManager (eventHub, this, this );

3. InputManager. cpp

The constructors include:

MDispatcher = new InputDispatcher (dispatcherPolicy );

MReader = new InputReader (eventHub, readerPolicy, mDispatcher );

By

Class NativeInputManager: public virtual RefBase,

Public virtual InputReaderPolicyInterface,

Public virtual InputDispatcherPolicyInterface,

Public virtual PointerControllerPolicyInterface {

} We can know that the second parameter of the InputManager constructor is actually the implementation of InputDispatcherPolicyInterface, that is, the instance of com_android_server_InputManager.

We know from the InputDispatcher statement that the policy here is actually com_android_server_InputManager.

InputDispatcher: InputDispatcher (const sp <InputDispatcherPolicyInterface> & policy ):

MPolicy (policy ),

MPendingEvent (NULL), mAppSwitchSawKeyDown (false), mAppSwitchDueTime (LONG_LONG_MAX ),

MNextUnblockedEvent (NULL ),

MDispatchEnabled (true), mDispatchFrozen (false), mInputFilterEnabled (false ),

MCurrentInputTargetsValid (false ),

MInputTargetWaitCause (INPUT_TARGET_WAIT_CAUSE_NONE)

After InputReader reads the event, it will wake up the InputDiapatcher function and then call InputDispatcher: policykey. For detailed analysis, see:

Http://blog.csdn.net/luoshengyang/article/details/6882903

4. InputDispatcher. cpp

Void InputDispatcher: policykey (const policykeyargs * args ){

......

// The mPolicy here is InputManager

MPolicy-> interceptKeyBeforeQueueing (& event, policyFlags );

......

}

5. Return to com_android_server_InputManager:

Void NativeInputManager: interceptKeyBeforeQueueing (const KeyEvent * keyEvent,

Uint32_t & policyFlags ){

If (policyFlags & POLICY_FLAG_TRUSTED )){

If (keyEventObj ){

// Here, we can clearly see that mCallbacksObj is Callbacks in InputManager. java.

// Call its interceptKeyBeforeQueueing.

WmActions = env-> CallIntMethod (mCallbacksObj,

GCallbacksClassInfo. interceptKeyBeforeQueueing,

KeyEventObj, policyFlags, isScreenOn );

If (checkAndClearExceptionFromCallback (env, "interceptKeyBeforeQueueing ")){

WmActions = 0;

}

Android_view_KeyEvent_recycle (env, keyEventObj );

Env-> DeleteLocalRef (keyEventObj );

}

}

}

Let's go back to the Callbacks definition in Step 1:

Public int interceptKeyBeforeQueueing (KeyEvent event, int policyFlags, boolean

IsScreenOn ){

Return mWindowManagerService. mInputMonitor. interceptKeyBeforeQueueing (

Event, policyFlags, isScreenOn );

}

InputMonitor. java

Public int interceptKeyBeforeQueueing (

KeyEvent event, int policyFlags, boolean isScreenOn ){

Return mService. mPolicy. interceptKeyBeforeQueueing (event, policyFlags, isScreenOn );

}

Here mService is WindowManagerService, and mPolicy is defined as follows (in WindowManagerService)

Final WindowManagerPolicy mPolicy = PolicyManager. makeNewWindowManager ();

Yymanager. java

Public static WindowManagerPolicy makeNewWindowManager (){

// SPolicy is the Policy instantiation.

Return sPolicy. makeNewWindowManager ();

}

Policy. java

Public WindowManagerPolicy makeNewWindowManager (){

Return new PhoneWindowManager ();

}

Now, the PhoneWindowManager instance is officially called.

Therefore, the code for processing the hardkey is in PhoneWindowManager.

Author: kakaBack