Android输入输出系统之TouchEvent流程

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一个是InputReader，一个是InputDispatcher。方法是dispatchTouch。

入口点是InputReader 的loopOnce方法.

InputReader里面有个线程叫做InputReaderThread，threadLoop

[code="java"]InputReaderThread::InputReaderThread(const sp& reader) :
        Thread(/*canCallJava*/ true), mReader(reader) {
}

InputReaderThread::~InputReaderThread() {
}

bool InputReaderThread::threadLoop() {
    mReader->loopOnce();
    return true;
}

Java代码  

1. void InputDispatcher::dispatchOnce() {  
2.     nsecs_t keyRepeatTimeout = mPolicy->getKeyRepeatTimeout();  
3.     nsecs_t keyRepeatDelay = mPolicy->getKeyRepeatDelay();  
4.   
5.     nsecs_t nextWakeupTime = LONG_LONG_MAX;  
6.     { // acquire lock  
7.         AutoMutex _l(mLock);  
8.         dispatchOnceInnerLocked(keyRepeatTimeout, keyRepeatDelay, & nextWakeupTime);  
9.   
10.         if (runCommandsLockedInterruptible()) {  
11.             nextWakeupTime = LONG_LONG_MIN;  // force next poll to wake up immediately  
12.         }  
13.     } // release lock  
14.   
15.     // Wait for callback or timeout or wake.  (make sure we round up, not down)  
16.     nsecs_t currentTime = now();  
17.     int32_t timeoutMillis;  
18.     if (nextWakeupTime > currentTime) {  
19.         uint64_t timeout = uint64_t(nextWakeupTime - currentTime);  
20.         timeout = (timeout + 999999LL) / 1000000LL;  
21.         timeoutMillis = timeout > INT_MAX ? -1 : int32_t(timeout);  
22.     } else {  
23.         timeoutMillis = 0;  
24.     }  
25.   
26.     mLooper->pollOnce(timeoutMillis);  
27. }  

Java代码  

1. case EventEntry::TYPE_MOTION: {  
2.     MotionEntry* typedEntry = static_cast<MotionEntry*>(mPendingEvent);  
3.     if (dropReason == DROP_REASON_NOT_DROPPED && isAppSwitchDue) {  
4.         dropReason = DROP_REASON_APP_SWITCH;  
5.     }  
6.     done = dispatchMotionLocked(currentTime, typedEntry,  
7.             &dropReason, nextWakeupTime);  
8.     break;  

Java代码  

1. bool InputDispatcher::dispatchMotionLocked(  
2.         nsecs_t currentTime, MotionEntry* entry, DropReason* dropReason, nsecs_t* nextWakeupTime) {  
3.     // Preprocessing.  
4.     if (! entry->dispatchInProgress) {  
5.         entry->dispatchInProgress = true;  
6.         resetTargetsLocked();  
7.   
8.         logOutboundMotionDetailsLocked("dispatchMotion - ", entry);  
9.     }  
10.   
11.     // Clean up if dropping the event.  
12.     if (*dropReason != DROP_REASON_NOT_DROPPED) {  
13.         resetTargetsLocked();  
14.         setInjectionResultLocked(entry, *dropReason == DROP_REASON_POLICY  
15.                 ? INPUT_EVENT_INJECTION_SUCCEEDED : INPUT_EVENT_INJECTION_FAILED);  
16.         return true;  
17.     }  
18.   
19.     bool isPointerEvent = entry->source & AINPUT_SOURCE_CLASS_POINTER;  
20.   
21.     // Identify targets.  
22.     if (! mCurrentInputTargetsValid) {  
23.         int32_t injectionResult;  
24.         if (isPointerEvent) {  
25.             // Pointer event.  (eg. touchscreen)  
26.             injectionResult = findTouchedWindowTargetsLocked(currentTime,  
27.                     entry, nextWakeupTime);  
28.         } else {  
29.             // Non touch event.  (eg. trackball)  
30.             injectionResult = findFocusedWindowTargetsLocked(currentTime,  
31.                     entry, nextWakeupTime);  
32.         }  
33.         if (injectionResult == INPUT_EVENT_INJECTION_PENDING) {  
34.             return false;  
35.         }  
36.   
37.         setInjectionResultLocked(entry, injectionResult);  
38.         if (injectionResult != INPUT_EVENT_INJECTION_SUCCEEDED) {  
39.             return true;  
40.         }  
41.   
42.         addMonitoringTargetsLocked();  
43.         commitTargetsLocked();  
44.     }  
45.   
46.     // Dispatch the motion.  
47.     dispatchEventToCurrentInputTargetsLocked(currentTime, entry, false);  
48.     return true;  
49. }  

Java代码  

1. startDispatchCycleLocked 中的方法  
2.  status = connection->inputPublisher.publishMotionEvent(motionEntry->deviceId,  
3.                 motionEntry->source, action, flags, motionEntry->edgeFlags, motionEntry->metaState,  
4.                 xOffset, yOffset,  
5.                 motionEntry->xPrecision, motionEntry->yPrecision,  
6.                 motionEntry->downTime, firstMotionSample->eventTime,  
7.                 motionEntry->pointerCount, motionEntry->pointerIds,  
8.                 firstMotionSample->pointerCoords);  

Java代码  

1. ViewRoot有个InputHandler  

Java代码  

1. private final InputHandler mInputHandler = new InputHandler() {  
2.     public void handleKey(KeyEvent event, Runnable finishedCallback) {  
3.         startInputEvent(finishedCallback);  
4.         dispatchKey(event, true);  
5.     }  
6.   
7.     public void handleMotion(MotionEvent event, Runnable finishedCallback) {  
8.         startInputEvent(finishedCallback);  
9.         dispatchMotion(event, true);  
10.     }  
11. };  

 InputHandler注册给了系统

Java代码  

1. InputQueue.registerInputChannel(mInputChannel, mInputHandler,  
2.                            Looper.myQueue());  

Java代码  

1. dispatchMotion(event, true);方法如下  
2. rivate void dispatchMotion(MotionEvent event, boolean sendDone) {  
3.        int source = event.getSource();  
4.        if ((source & InputDevice.SOURCE_CLASS_POINTER) != 0) {  
5.            dispatchPointer(event, sendDone);  
6.        } else if ((source & InputDevice.SOURCE_CLASS_TRACKBALL) != 0) {  
7.            dispatchTrackball(event, sendDone);  
8.        } else {  
9.            // TODO  
10.            Log.v(TAG, "Dropping unsupported motion event (unimplemented): " + event);  
11.            if (sendDone) {  
12.                finishInputEvent();  
13.            }  
14.        }  
15.    }   

调用了dispatchPointer

 ViewRoot本身就是Handler直接sendMessageAtTime

然后就进入了View的焦点系统。

下面就说一下Activity的焦点是怎么回事。

Java代码  

1. InputDisapatcher.cpp中调用了如下方法  
2.   
3.  dispatchEventToCurrentInputTargetsLocked(currentTime, motionEntry,  
4.                             true /*resumeWithAppendedMotionSample*/);  

 然后

Java代码  

1. dispatchEventToCurrentInputTargetsLocked  

调用了如下方法

Java代码  

1. int32_t InputDispatcher::findFocusedWindowTargetsLocked(nsecs_t currentTime,  
2.         const EventEntry* entry, nsecs_t* nextWakeupTime) {  
3.     mCurrentInputTargets.clear();  
4.   
5.     int32_t injectionResult;  
6.   
7.     // If there is no currently focused window and no focused application  
8.     // then drop the event.  
9.     if (! mFocusedWindow) {  
10.         if (mFocusedApplication) {  
11. #if DEBUG_FOCUS  
12.             LOGD("Waiting because there is no focused window but there is a "  
13.                     "focused application that may eventually add a window: %s.",  
14.                     getApplicationWindowLabelLocked(mFocusedApplication, NULL).string());  
15. #endif  
16.             injectionResult = handleTargetsNotReadyLocked(currentTime, entry,  
17.                     mFocusedApplication, NULL, nextWakeupTime);  
18.             goto Unresponsive;  
19.         }  
20.   
21.         LOGI("Dropping event because there is no focused window or focused application.");  
22.         injectionResult = INPUT_EVENT_INJECTION_FAILED;  
23.         goto Failed;  
24.     }  
25.   
26.     // Check permissions.  
27.     if (! checkInjectionPermission(mFocusedWindow, entry->injectionState)) {  
28.         injectionResult = INPUT_EVENT_INJECTION_PERMISSION_DENIED;  
29.         goto Failed;  
30.     }  
31.   
32.     // If the currently focused window is paused then keep waiting.  
33.     if (mFocusedWindow->paused) {  
34. #if DEBUG_FOCUS  
35.         LOGD("Waiting because focused window is paused.");  
36. #endif  
37.         injectionResult = handleTargetsNotReadyLocked(currentTime, entry,  
38.                 mFocusedApplication, mFocusedWindow, nextWakeupTime);  
39.         goto Unresponsive;  
40.     }  
41.   
42.     // If the currently focused window is still working on previous events then keep waiting.  
43.     if (! isWindowFinishedWithPreviousInputLocked(mFocusedWindow)) {  
44. #if DEBUG_FOCUS  
45.         LOGD("Waiting because focused window still processing previous input.");  
46. #endif  
47.         injectionResult = handleTargetsNotReadyLocked(currentTime, entry,  
48.                 mFocusedApplication, mFocusedWindow, nextWakeupTime);  
49.         goto Unresponsive;  
50.     }  
51.   
52.     // Success!  Output targets.  
53.     injectionResult = INPUT_EVENT_INJECTION_SUCCEEDED;  
54.     addWindowTargetLocked(mFocusedWindow, InputTarget::FLAG_FOREGROUND, BitSet32(0));  
55.   
56.     // Done.  
57. Failed:  
58. Unresponsive:  
59.     nsecs_t timeSpentWaitingForApplication = getTimeSpentWaitingForApplicationLocked(currentTime);  
60.     updateDispatchStatisticsLocked(currentTime, entry,  
61.             injectionResult, timeSpentWaitingForApplication);  
62. #if DEBUG_FOCUS  
63.     LOGD("findFocusedWindow finished: injectionResult=%d, "  
64.             "timeSpendWaitingForApplication=%0.1fms",  
65.             injectionResult, timeSpentWaitingForApplication / 1000000.0);  
66. #endif  
67.     return injectionResult;  
68. }  

move事件的处理和Down事件的处理很不相同。

新建立的Window在处理焦点的时候，按下事件没有起来之前，保持了原来的焦点窗口。除非ACTION_UP事件收到以后

Java代码  

1. /* Updates the cached window information provided to the input dispatcher. */  
2.        public void updateInputWindowsLw() {  
3.            // Populate the input window list with information about all of the windows that  
4.            // could potentially receive input.  
5.            // As an optimization, we could try to prune the list of windows but this turns  
6.            // out to be difficult because only the native code knows for sure which window  
7.            // currently has touch focus.  
8.            final ArrayList<WindowState> windows = mWindows;  
9.            final int N = windows.size();  
10.            for (int i = N - 1; i >= 0; i--) {  
11.                final WindowState child = windows.get(i);  
12.                if (child.mInputChannel == null || child.mRemoved) {  
13.                    // Skip this window because it cannot possibly receive input.  
14.                    continue;  
15.                }  
16.                  
17.                final int flags = child.mAttrs.flags;  
18.                final int type = child.mAttrs.type;  
19.                  
20.                final boolean hasFocus = (child == mInputFocus);  
21.                final boolean isVisible = child.isVisibleLw();  
22.                final boolean hasWallpaper = (child == mWallpaperTarget)  
23.                        && (type != WindowManager.LayoutParams.TYPE_KEYGUARD);  
24.                  
25.                // Add a window to our list of input windows.  
26.                final InputWindow inputWindow = mTempInputWindows.add();  
27.                inputWindow.inputChannel = child.mInputChannel;  
28.                inputWindow.name = child.toString();  
29.                inputWindow.layoutParamsFlags = flags;  
30.                inputWindow.layoutParamsType = type;  
31.                inputWindow.dispatchingTimeoutNanos = child.getInputDispatchingTimeoutNanos();  
32.                inputWindow.visible = isVisible;  
33.                inputWindow.canReceiveKeys = child.canReceiveKeys();  
34.                inputWindow.hasFocus = hasFocus;  
35.                inputWindow.hasWallpaper = hasWallpaper;  
36.                inputWindow.paused = child.mAppToken != null ? child.mAppToken.paused : false;  
37.                inputWindow.layer = child.mLayer;  
38.                inputWindow.ownerPid = child.mSession.mPid;  
39.                inputWindow.ownerUid = child.mSession.mUid;  
40.                  
41.                final Rect frame = child.mFrame;  
42.                inputWindow.frameLeft = frame.left;  
43.                inputWindow.frameTop = frame.top;  
44.                inputWindow.frameRight = frame.right;  
45.                inputWindow.frameBottom = frame.bottom;  
46.                  
47.                final Rect visibleFrame = child.mVisibleFrame;  
48.                inputWindow.visibleFrameLeft = visibleFrame.left;  
49.                inputWindow.visibleFrameTop = visibleFrame.top;  
50.                inputWindow.visibleFrameRight = visibleFrame.right;  
51.                inputWindow.visibleFrameBottom = visibleFrame.bottom;  
52.                  
53.                switch (child.mTouchableInsets) {  
54.                    default:  
55.                    case ViewTreeObserver.InternalInsetsInfo.TOUCHABLE_INSETS_FRAME:  
56.                        inputWindow.touchableAreaLeft = frame.left;  
57.                        inputWindow.touchableAreaTop = frame.top;  
58.                        inputWindow.touchableAreaRight = frame.right;  
59.                        inputWindow.touchableAreaBottom = frame.bottom;  
60.                        break;  
61.                          
62.                    case ViewTreeObserver.InternalInsetsInfo.TOUCHABLE_INSETS_CONTENT: {  
63.                        Rect inset = child.mGivenContentInsets;  
64.                        inputWindow.touchableAreaLeft = frame.left + inset.left;  
65.                        inputWindow.touchableAreaTop = frame.top + inset.top;  
66.                        inputWindow.touchableAreaRight = frame.right - inset.right;  
67.                        inputWindow.touchableAreaBottom = frame.bottom - inset.bottom;  
68.                        break;  
69.                    }  
70.                          
71.                    case ViewTreeObserver.InternalInsetsInfo.TOUCHABLE_INSETS_VISIBLE: {  
72.                        Rect inset = child.mGivenVisibleInsets;  
73.                        inputWindow.touchableAreaLeft = frame.left + inset.left;  
74.                        inputWindow.touchableAreaTop = frame.top + inset.top;  
75.                        inputWindow.touchableAreaRight = frame.right - inset.right;  
76.                        inputWindow.touchableAreaBottom = frame.bottom - inset.bottom;  
77.                        break;  
78.                    }  
79.                }  
80.            }  
81.   
82.            // Send windows to native code.  
83.            mInputManager.setInputWindows(mTempInputWindows.toNullTerminatedArray());  
84.              
85.            // Clear the list in preparation for the next round.  
86.            // Also avoids keeping InputChannel objects referenced unnecessarily.  
87.            mTempInputWindows.clear();  
88.        }  

  真正的Input的控制是通过以下方式

      /**
     * Z-ordered (bottom-most first) list of all Window objects.
     */
    final ArrayList<WindowState> mWindows = new ArrayList<WindowState>();

Java代码  

1. /** 
2.  * Z-ordered (bottom-most first) list of all Window objects. 
3.  */  
4. final ArrayList<WindowState> mWindows = new ArrayList<WindowState>();  

另外的touch的target并不是通过input focus 获得的。而是通过visible来获得

Java代码  

1. int32_t InputDispatcher::findTouchedWindowTargetsLocked(nsecs_t currentTime,  
2.         const MotionEntry* entry, nsecs_t* nextWakeupTime) {  
3.     enum InjectionPermission {  
4.         INJECTION_PERMISSION_UNKNOWN,  
5.         INJECTION_PERMISSION_GRANTED,  
6.         INJECTION_PERMISSION_DENIED  
7.     };  
8.   
9.     mCurrentInputTargets.clear();  
10.   
11.     nsecs_t startTime = now();  
12.   
13.     // For security reasons, we defer updating the touch state until we are sure that  
14.     // event injection will be allowed.  
15.     //  
16.     // FIXME In the original code, screenWasOff could never be set to true.  
17.     //       The reason is that the POLICY_FLAG_WOKE_HERE  
18.     //       and POLICY_FLAG_BRIGHT_HERE flags were set only when preprocessing raw  
19.     //       EV_KEY, EV_REL and EV_ABS events.  As it happens, the touch event was  
20.     //       actually enqueued using the policyFlags that appeared in the final EV_SYN  
21.     //       events upon which no preprocessing took place.  So policyFlags was always 0.  
22.     //       In the new native input dispatcher we‘re a bit more careful about event  
23.     //       preprocessing so the touches we receive can actually have non-zero policyFlags.  
24.     //       Unfortunately we obtain undesirable behavior.  
25.     //  
26.     //       Here‘s what happens:  
27.     //  
28.     //       When the device dims in anticipation of going to sleep, touches  
29.     //       in windows which have FLAG_TOUCHABLE_WHEN_WAKING cause  
30.     //       the device to brighten and reset the user activity timer.  
31.     //       Touches on other windows (such as the launcher window)  
32.     //       are dropped.  Then after a moment, the device goes to sleep.  Oops.  
33.     //  
34.     //       Also notice how screenWasOff was being initialized using POLICY_FLAG_BRIGHT_HERE  
35.     //       instead of POLICY_FLAG_WOKE_HERE...  
36.     //  
37.     bool screenWasOff = false; // original policy: policyFlags & POLICY_FLAG_BRIGHT_HERE;  
38.   
39.     int32_t action = entry->action;  
40.     int32_t maskedAction = action & AMOTION_EVENT_ACTION_MASK;  
41.   
42.     // Update the touch state as needed based on the properties of the touch event.  
43.     int32_t injectionResult = INPUT_EVENT_INJECTION_PENDING;  
44.     InjectionPermission injectionPermission = INJECTION_PERMISSION_UNKNOWN;  
45.     if (maskedAction == AMOTION_EVENT_ACTION_DOWN) {  
46.         mTempTouchState.reset();  
47.         mTempTouchState.down = true;  
48.     } else {  
49.         mTempTouchState.copyFrom(mTouchState);  
50.     }  
51.   
52.     bool isSplit = mTempTouchState.split && mTempTouchState.down;  
53.     if (maskedAction == AMOTION_EVENT_ACTION_DOWN  
54.             || (isSplit && maskedAction == AMOTION_EVENT_ACTION_POINTER_DOWN)) {  
55.         /* Case 1: New splittable pointer going down. */  
56.   
57.         int32_t pointerIndex = getMotionEventActionPointerIndex(action);  
58.         int32_t x = int32_t(entry->firstSample.pointerCoords[pointerIndex].x);  
59.         int32_t y = int32_t(entry->firstSample.pointerCoords[pointerIndex].y);  
60.         const InputWindow* newTouchedWindow = NULL;  
61.         const InputWindow* topErrorWindow = NULL;  
62.   
63.         // Traverse windows from front to back to find touched window and outside targets.  
64.         size_t numWindows = mWindows.size();  
65.         for (size_t i = 0; i < numWindows; i++) {  
66.             const InputWindow* window = & mWindows.editItemAt(i);  
67.             int32_t flags = window->layoutParamsFlags;  
68.   
69.             if (flags & InputWindow::FLAG_SYSTEM_ERROR) {  
70.                 if (! topErrorWindow) {  
71.                     topErrorWindow = window;  
72.                 }  
73.             }  
74.   
75.             if (window->visible) {  
76.                 if (! (flags & InputWindow::FLAG_NOT_TOUCHABLE)) {  
77.                     bool isTouchModal = (flags & (InputWindow::FLAG_NOT_FOCUSABLE  
78.                             | InputWindow::FLAG_NOT_TOUCH_MODAL)) == 0;  
79.                     if (isTouchModal || window->touchableAreaContainsPoint(x, y)) {  
80.                         if (! screenWasOff || flags & InputWindow::FLAG_TOUCHABLE_WHEN_WAKING) {  
81.                             newTouchedWindow = window;  
82.                         }  
83.                         break; // found touched window, exit window loop  
84.                     }  
85.                 }  
86.   
87.                 if (maskedAction == AMOTION_EVENT_ACTION_DOWN  
88.                         && (flags & InputWindow::FLAG_WATCH_OUTSIDE_TOUCH)) {  
89.                     int32_t outsideTargetFlags = InputTarget::FLAG_OUTSIDE;  
90.                     if (isWindowObscuredAtPointLocked(window, x, y)) {  
91.                         outsideTargetFlags |= InputTarget::FLAG_WINDOW_IS_OBSCURED;  
92.                     }  
93.   
94.                     mTempTouchState.addOrUpdateWindow(window, outsideTargetFlags, BitSet32(0));  
95.                 }  
96.             }  
97.         }  
98.   
99.         // If there is an error window but it is not taking focus (typically because  
100.         // it is invisible) then wait for it.  Any other focused window may in  
101.         // fact be in ANR state.  
102.         if (topErrorWindow && newTouchedWindow != topErrorWindow) {  
103. #if DEBUG_FOCUS  
104.             LOGD("Waiting because system error window is pending.");  
105. #endif  
106.             injectionResult = handleTargetsNotReadyLocked(currentTime, entry,  
107.                     NULL, NULL, nextWakeupTime);  
108.             injectionPermission = INJECTION_PERMISSION_UNKNOWN;  
109.             goto Unresponsive;  
110.         }  
111.   
112.         // Figure out whether splitting will be allowed for this window.  
113.         if (newTouchedWindow  
114.                 && (newTouchedWindow->layoutParamsFlags & InputWindow::FLAG_SPLIT_TOUCH)) {  
115.             // New window supports splitting.  
116.             isSplit = true;  
117.         } else if (isSplit) {  
118.             // New window does not support splitting but we have already split events.  
119.             // Assign the pointer to the first foreground window we find.  
120.             // (May be NULL which is why we put this code block before the next check.)  
121.             newTouchedWindow = mTempTouchState.getFirstForegroundWindow();  
122.         }  
123.   
124.         // If we did not find a touched window then fail.  
125.         if (! newTouchedWindow) {  
126.             if (mFocusedApplication) {  
127. #if DEBUG_FOCUS  
128.                 LOGD("Waiting because there is no touched window but there is a "  
129.                         "focused application that may eventually add a new window: %s.",  
130.                         getApplicationWindowLabelLocked(mFocusedApplication, NULL).string());  
131. #endif  
132.                 injectionResult = handleTargetsNotReadyLocked(currentTime, entry,  
133.                         mFocusedApplication, NULL, nextWakeupTime);  
134.                 goto Unresponsive;  
135.             }  
136.   
137.             LOGI("Dropping event because there is no touched window or focused application.");  
138.             injectionResult = INPUT_EVENT_INJECTION_FAILED;  
139.             goto Failed;  
140.         }  
141.   
142.         // Set target flags.  
143.         int32_t targetFlags = InputTarget::FLAG_FOREGROUND;  
144.         if (isSplit) {  
145.             targetFlags |= InputTarget::FLAG_SPLIT;  
146.         }  
147.         if (isWindowObscuredAtPointLocked(newTouchedWindow, x, y)) {  
148.             targetFlags |= InputTarget::FLAG_WINDOW_IS_OBSCURED;  
149.         }  
150.   
151.         // Update the temporary touch state.  
152.         BitSet32 pointerIds;  
153.         if (isSplit) {  
154.             uint32_t pointerId = entry->pointerIds[pointerIndex];  
155.             pointerIds.markBit(pointerId);  
156.         }  
157.         mTempTouchState.addOrUpdateWindow(newTouchedWindow, targetFlags, pointerIds);  
158.     } else {  
159.         /* Case 2: Pointer move, up, cancel or non-splittable pointer down. */  
160.   
161.         // If the pointer is not currently down, then ignore the event.  
162.         if (! mTempTouchState.down) {  
163.             LOGI("Dropping event because the pointer is not down.");  
164.             injectionResult = INPUT_EVENT_INJECTION_FAILED;  
165.             goto Failed;  
166.         }  
167.     }  
168.   
169.     // Check permission to inject into all touched foreground windows and ensure there  
170.     // is at least one touched foreground window.  
171.     {  
172.         bool haveForegroundWindow = false;  
173.         for (size_t i = 0; i < mTempTouchState.windows.size(); i++) {  
174.             const TouchedWindow& touchedWindow = mTempTouchState.windows[i];  
175.             if (touchedWindow.targetFlags & InputTarget::FLAG_FOREGROUND) {  
176.                 haveForegroundWindow = true;  
177.                 if (! checkInjectionPermission(touchedWindow.window, entry->injectionState)) {  
178.                     injectionResult = INPUT_EVENT_INJECTION_PERMISSION_DENIED;  
179.                     injectionPermission = INJECTION_PERMISSION_DENIED;  
180.                     goto Failed;  
181.                 }  
182.             }  
183.         }  
184.         if (! haveForegroundWindow) {  
185. #if DEBUG_INPUT_DISPATCHER_POLICY  
186.             LOGD("Dropping event because there is no touched foreground window to receive it.");  
187. #endif  
188.             injectionResult = INPUT_EVENT_INJECTION_FAILED;  
189.             goto Failed;  
190.         }  
191.   
192.         // Permission granted to injection into all touched foreground windows.  
193.         injectionPermission = INJECTION_PERMISSION_GRANTED;  
194.     }  
195.   
196.     // Ensure all touched foreground windows are ready for new input.  
197.     for (size_t i = 0; i < mTempTouchState.windows.size(); i++) {  
198.         const TouchedWindow& touchedWindow = mTempTouchState.windows[i];  
199.         if (touchedWindow.targetFlags & InputTarget::FLAG_FOREGROUND) {  
200.             // If the touched window is paused then keep waiting.  
201.             if (touchedWindow.window->paused) {  
202. #if DEBUG_INPUT_DISPATCHER_POLICY  
203.                 LOGD("Waiting because touched window is paused.");  
204. #endif  
205.                 injectionResult = handleTargetsNotReadyLocked(currentTime, entry,  
206.                         NULL, touchedWindow.window, nextWakeupTime);  
207.                 goto Unresponsive;  
208.             }  
209.   
210.             // If the touched window is still working on previous events then keep waiting.  
211.             if (! isWindowFinishedWithPreviousInputLocked(touchedWindow.window)) {  
212. #if DEBUG_FOCUS  
213.                 LOGD("Waiting because touched window still processing previous input.");  
214. #endif  
215.                 injectionResult = handleTargetsNotReadyLocked(currentTime, entry,  
216.                         NULL, touchedWindow.window, nextWakeupTime);  
217.                 goto Unresponsive;  
218.             }  
219.         }  
220.     }  
221.   
222.     // If this is the first pointer going down and the touched window has a wallpaper  
223.     // then also add the touched wallpaper windows so they are locked in for the duration  
224.     // of the touch gesture.  
225.     if (maskedAction == AMOTION_EVENT_ACTION_DOWN) {  
226.         const InputWindow* foregroundWindow = mTempTouchState.getFirstForegroundWindow();  
227.         if (foregroundWindow->hasWallpaper) {  
228.             for (size_t i = 0; i < mWindows.size(); i++) {  
229.                 const InputWindow* window = & mWindows[i];  
230.                 if (window->layoutParamsType == InputWindow::TYPE_WALLPAPER) {  
231.                     mTempTouchState.addOrUpdateWindow(window,  
232.                             InputTarget::FLAG_WINDOW_IS_OBSCURED, BitSet32(0));  
233.                 }  
234.             }  
235.         }  
236.     }  
237.   
238.     // Success!  Output targets.  
239.     injectionResult = INPUT_EVENT_INJECTION_SUCCEEDED;  
240.   
241.     for (size_t i = 0; i < mTempTouchState.windows.size(); i++) {  
242.         const TouchedWindow& touchedWindow = mTempTouchState.windows.itemAt(i);  
243.         addWindowTargetLocked(touchedWindow.window, touchedWindow.targetFlags,  
244.                 touchedWindow.pointerIds);  
245.     }  
246.   
247.     // Drop the outside touch window since we will not care about them in the next iteration.  
248.     mTempTouchState.removeOutsideTouchWindows();  
249.   
250. Failed:  
251.     // Check injection permission once and for all.  
252.     if (injectionPermission == INJECTION_PERMISSION_UNKNOWN) {  
253.         if (checkInjectionPermission(NULL, entry->injectionState)) {  
254.             injectionPermission = INJECTION_PERMISSION_GRANTED;  
255.         } else {  
256.             injectionPermission = INJECTION_PERMISSION_DENIED;  
257.         }  
258.     }  
259.   
260.     // Update final pieces of touch state if the injector had permission.  
261.     if (injectionPermission == INJECTION_PERMISSION_GRANTED) {  
262.         if (maskedAction == AMOTION_EVENT_ACTION_UP  
263.                 || maskedAction == AMOTION_EVENT_ACTION_CANCEL) {  
264.             // All pointers up or canceled.  
265.             mTempTouchState.reset();  
266.         } else if (maskedAction == AMOTION_EVENT_ACTION_DOWN) {  
267.             // First pointer went down.  
268.             if (mTouchState.down) {  
269. #if DEBUG_FOCUS  
270.                 LOGD("Pointer down received while already down.");  
271. #endif  
272.             }  
273.         } else if (maskedAction == AMOTION_EVENT_ACTION_POINTER_UP) {  
274.             // One pointer went up.  
275.             if (isSplit) {  
276.                 int32_t pointerIndex = getMotionEventActionPointerIndex(action);  
277.                 uint32_t pointerId = entry->pointerIds[pointerIndex];  
278.   
279.                 for (size_t i = 0; i < mTempTouchState.windows.size(); ) {  
280.                     TouchedWindow& touchedWindow = mTempTouchState.windows.editItemAt(i);  
281.                     if (touchedWindow.targetFlags & InputTarget::FLAG_SPLIT) {  
282.                         touchedWindow.pointerIds.clearBit(pointerId);  
283.                         if (touchedWindow.pointerIds.isEmpty()) {  
284.                             mTempTouchState.windows.removeAt(i);  
285.                             continue;  
286.                         }  
287.                     }  
288.                     i += 1;  
289.                 }  
290.             }  
291.         }  
292.   
293.         // Save changes to touch state.  
294.         mTouchState.copyFrom(mTempTouchState);  
295.     } else {  
296. #if DEBUG_FOCUS  
297.         LOGD("Not updating touch focus because injection was denied.");  
298. #endif  
299.     }  
300.   
301. Unresponsive:  
302.     // Reset temporary touch state to ensure we release unnecessary references to input channels.  
303.     mTempTouchState.reset();  
304.   
305.     nsecs_t timeSpentWaitingForApplication = getTimeSpentWaitingForApplicationLocked(currentTime);  
306.     updateDispatchStatisticsLocked(currentTime, entry,  
307.             injectionResult, timeSpentWaitingForApplication);  
308. #if DEBUG_FOCUS  
309.     LOGD("findTouchedWindow finished: injectionResult=%d, injectionPermission=%d, "  
310.             "timeSpentWaitingForApplication=%0.1fms",  
311.             injectionResult, injectionPermission, timeSpentWaitingForApplication / 1000000.0);  
312. #endif  
313.     return injectionResult;  
314. }  

  最关键的几行代码，说明了Windows是如何找到触屏的输入焦点的：

Cpp代码  

1. if (window->visible) {    
2.               if (! (flags & InputWindow::FLAG_NOT_TOUCHABLE)) {    
3.                   bool isTouchModal = (flags & (InputWindow::FLAG_NOT_FOCUSABLE    
4.                           | InputWindow::FLAG_NOT_TOUCH_MODAL)) == 0;    
5.                   if (isTouchModal || window->touchableAreaContainsPoint(x, y)) {    
6.                       if (! screenWasOff || flags & InputWindow::FLAG_TOUCHABLE_WHEN_WAKING) {    
7.                           newTouchedWindow = window;    
8.                       }    
9.                       break; // found touched window, exit window loop    
10.                   }    
11.               }    
12.   
13.               if (maskedAction == AMOTION_EVENT_ACTION_DOWN    
14.                       && (flags & InputWindow::FLAG_WATCH_OUTSIDE_TOUCH)) {    
15.                   int32_t outsideTargetFlags = InputTarget::FLAG_OUTSIDE;    
16.                   if (isWindowObscuredAtPointLocked(window, x, y)) {    
17.                       outsideTargetFlags |= InputTarget::FLAG_WINDOW_IS_OBSCURED;    
18.                   }    
19.   
20.                   mTempTouchState.addOrUpdateWindow(window, outsideTargetFlags, BitSet32(0));    
21.               }    
22.           }    

Java代码  

1.  // Focus tracking for touch.  
2.     struct TouchedWindow {  
3.         const InputWindow* window;  
4.         int32_t targetFlags;  
5.         BitSet32 pointerIds;  
6.         sp<InputChannel> channel;  
7.     };  
8.     struct TouchState {  
9.         bool down;  
10.         bool split;  
11.         Vector<TouchedWindow> windows;  
12.   
13.         TouchState();  
14.         ~TouchState();  
15.         void reset();  
16.         void copyFrom(const TouchState& other);  
17.         void addOrUpdateWindow(const InputWindow* window, int32_t targetFlags, BitSet32 pointerIds);  
18.         void removeOutsideTouchWindows();  
19.         const InputWindow* getFirstForegroundWindow();  
20.     };  
21.   
22.   
23.   
24. 另外如何定义按键和其他触屏焦点的：  
25.   
26.   
27.         /* Updates the cached window information provided to the input dispatcher. */  
28.         public void updateInputWindowsLw() {  
29.             // Populate the input window list with information about all of the windows that  
30.             // could potentially receive input.  
31.             // As an optimization, we could try to prune the list of windows but this turns  
32.             // out to be difficult because only the native code knows for sure which window  
33.             // currently has touch focus.  
34.             final ArrayList<WindowState> windows = mWindows;  
35.             final int N = windows.size();  
36.             for (int i = N - 1; i >= 0; i--) {  
37.                 final WindowState child = windows.get(i);  
38.                 if (child.mInputChannel == null || child.mRemoved) {  
39.                     // Skip this window because it cannot possibly receive input.  
40.                     continue;  
41.                 }  
42.                   
43.                 final int flags = child.mAttrs.flags;  
44.                 final int type = child.mAttrs.type;  
45.                   
46.                <span style="color: #ff6600;"> final boolean hasFocus = (child == mInputFocus);</span>  
47. //本行代码确定，一次性的focusWindow只有一个。  
48.                 final boolean isVisible = child.isVisibleLw();  
49.                 final boolean hasWallpaper = (child == mWallpaperTarget)  
50.                         && (type != WindowManager.LayoutParams.TYPE_KEYGUARD);    

Android输入输出系统之TouchEvent流程

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原文地址：http://www.cnblogs.com/xiaochao1234/p/4023845.html