程序焦点获取事件导致输入法显示

从上面可以知道程序获得焦点时，程序端会先间接的调用IMMS的startInput将焦点View绑定到输入法，然后会调用IMMS的windowGainFocus函数，这个函数就可能显示输入法, 是否显示输入法由焦点view的属性决定。过程流程图如下：

代码处理逻辑如下：

      //ViewRootImpl.java            case MSG_WINDOW_FOCUS_CHANGED: {                    if (hasWindowFocus) {                        if (imm != null && mLastWasImTarget && !isInLocalFocusMode()) {                            imm.onWindowFocus(mView, mView.findFocus(),                                    mWindowAttributes.softInputMode,                                    !mHasHadWindowFocus, mWindowAttributes.flags);                        }                    }            }     //InputMethodManager     public void onWindowFocus(View rootView, View focusedView, int softInputMode,            boolean first, int windowFlags) {        boolean forceNewFocus = false;        synchronized (mH) {            //和上面view获取焦点事件的处理一样            focusInLocked(focusedView != null ? focusedView : rootView);        }        //确认当前focused view是否已经调用过startInputInner来绑定输入法        //因为在前面mView.dispatchWindowFocusChanged处理过程focused view已经完成        //了绑定，所以大部分情况下，该函数返回false，即不会再次调用startInputInner        if (checkFocusNoStartInput(forceNewFocus, true)) {            if (startInputInner(rootView.getWindowToken(),                    controlFlags, softInputMode, windowFlags)) {                return;            }        }        synchronized (mH) {            try {                //调用IMMS windowGainedFocus函数                mService.windowGainedFocus(mClient, rootView.getWindowToken(),                        controlFlags, softInputMode, windowFlags, null, null);            } catch (RemoteException e) {            }        }    }

输入法响应显示请求

从上面可以看出，输入法响应显示请求是通过IInputMethod，而这个是在输入法service完成启动通过onBind接口传递过去的，所以我们先来看下这个IInputMethod的实现是什么？

输入法service都是继承InputMethodService类

public class InputMethodService extends AbstractInputMethodService {    @Override    public AbstractInputMethodImpl onCreateInputMethodInterface() {        return new InputMethodImpl();    }}public abstract class AbstractInputMethodService extends Service        implements KeyEvent.Callback {    private InputMethod mInputMethod;    @Override    final public IBinder onBind(Intent intent) {        if (mInputMethod == null) {            mInputMethod = onCreateInputMethodInterface();        }        return new IInputMethodWrapper(this, mInputMethod);}}

从上可见IMMS保存的IInputMethod的实现是封装了 InputMethodImpl的类 IInputMethodWrapper，那肯定就是它负责处理消息MSG_SHOW_SOFT_INPUT，处理逻辑如下。

    public IInputMethodWrapper(AbstractInputMethodService context,            InputMethod inputMethod) {        mTarget = new WeakReference<AbstractInputMethodService>(context);        mCaller = new HandlerCaller(context.getApplicationContext(), null,                this, true /*asyncHandler*/);        mInputMethod = new WeakReference<InputMethod>(inputMethod);        mTargetSdkVersion = context.getApplicationInfo().targetSdkVersion;    }    public InputMethod getInternalInputMethod() {        return mInputMethod.get();    }    @Override    public void executeMessage(Message msg) {        InputMethod inputMethod = mInputMethod.get();        switch (msg.what) {            case DO_SHOW_SOFT_INPUT:                //这个inputMethod是通过onCreateInputMethodInterface函数创建的                //InputMethodImpl对象                inputMethod.showSoftInput(msg.arg1, (ResultReceiver)msg.obj);                return;        }    }    public class InputMethodImpl extends AbstractInputMethodImpl {        public void showSoftInput(int flags, ResultReceiver resultReceiver) {            boolean wasVis = isInputViewShown();            mShowInputFlags = 0;            if (onShowInputRequested(flags, false)) {                try {                    //这个是真正显示UI的函数                    showWindow(true);                }            }        }    }    public class InputMethodService extends AbstractInputMethodService {    @Override public void onCreate() {        mTheme = Resources.selectSystemTheme(mTheme,                getApplicationInfo().targetSdkVersion,                android.R.style.Theme_InputMethod,                android.R.style.Theme_Holo_InputMethod,                android.R.style.Theme_DeviceDefault_InputMethod);        // SoftInputWindow就是大家一般用的Dialog的子类        mWindow = new SoftInputWindow(this, mTheme, mDispatcherState);        initViews();        mWindow.getWindow().setLayout(MATCH_PARENT, WRAP_CONTENT);    }    public void showWindow(boolean showInput) {                try {            mWindowWasVisible = mWindowVisible;            mInShowWindow = true;            showWindowInner(showInput);        } finally {            mWindowWasVisible = true;            mInShowWindow = false;        }    }        void showWindowInner(boolean showInput) {        initialize();        updateFullscreenMode();        //这个函数会创建输入法的键盘        updateInputViewShown();                if (!mWindowAdded || !mWindowCreated) {            mWindowAdded = true;            mWindowCreated = true;            initialize();            //创建输入法dialog里的词条选择View            View v = onCreateCandidatesView();            if (v != null) {                setCandidatesView(v);            }        }        if (mShowInputRequested) {            if (!mInputViewStarted) {                mInputViewStarted = true;                onStartInputView(mInputEditorInfo, false);            }        } else if (!mCandidatesViewStarted) {            mCandidatesViewStarted = true;            onStartCandidatesView(mInputEditorInfo, false);        }        if (!wasVisible) {            mImm.setImeWindowStatus(mToken, IME_ACTIVE, mBackDisposition);            onWindowShown();            //这个是Dialog的window,这里开始就显示UI了            mWindow.show();        }    }    public void updateInputViewShown() {        boolean isShown = mShowInputRequested && onEvaluateInputViewShown();        if (mIsInputViewShown != isShown && mWindowVisible) {            mIsInputViewShown = isShown;            mInputFrame.setVisibility(isShown ? View.VISIBLE : View.GONE);            if (mInputView == null) {                initialize();                //这个是核心view，创建显示键盘的根view                View v = onCreateInputView();                if (v != null) {                    setInputView(v);                }            }        }    }}

用户单击输入框View导致输入法显示

在上一篇InputChannel章节我们说到，事件传递到程序端，最后让ViewPostImeInputStage来处。处理逻辑如下：

    final class ViewPostImeInputStage extends InputStage {        public ViewPostImeInputStage(InputStage next) {            super(next);        }        @Override        protected int onProcess(QueuedInputEvent q) {            if (q.mEvent instanceof KeyEvent) {            } else {                final int source = q.mEvent.getSource();                if ((source & InputDevice.SOURCE_CLASS_POINTER) != 0) {                    //处理touch事件                    return processPointerEvent(q);                }            }        }        private int processPointerEvent(QueuedInputEvent q) {            final MotionEvent event = (MotionEvent)q.mEvent;            if (mView.dispatchPointerEvent(event)) {                return FINISH_HANDLED;            }            return FORWARD;        }    }

从上可知最后会调用DecorView的dispatchPointerEvent，DecorView也是一个view,所以该函数其实就是View的dispatchPointerEvent函数。

    //View.java    public final boolean dispatchPointerEvent(MotionEvent event) {        if (event.isTouchEvent()) {            return dispatchTouchEvent(event);        }   }    //DecorView又是一个ViewGroup，所以会调用ViewGroup的dispatchTouchEvent    //ViewGroup.java    public boolean dispatchTouchEvent(MotionEvent ev) {        if (mInputEventConsistencyVerifier != null) {            mInputEventConsistencyVerifier.onTouchEvent(ev, 1);        }        boolean handled = false;        if (onFilterTouchEventForSecurity(ev)) {            final int action = ev.getAction();            final int actionMasked = action & MotionEvent.ACTION_MASK;            // Handle an initial down.            if (actionMasked == MotionEvent.ACTION_DOWN) {                // Throw away all previous state when starting a new touch gesture.                // The framework may have dropped the up or cancel event for the previous gesture                // due to an app switch, ANR, or some other state change.                cancelAndClearTouchTargets(ev);                resetTouchState();            }            // Check for interception.            final boolean intercepted;            if (actionMasked == MotionEvent.ACTION_DOWN                    || mFirstTouchTarget != null) {                final boolean disallowIntercept = (mGroupFlags & FLAG_DISALLOW_INTERCEPT) != 0;                if (!disallowIntercept) {                    //先给该view一个处理事件的机会，如果Intercept，则事件不会往                    //下发送                    intercepted = onInterceptTouchEvent(ev);                    ev.setAction(action); // restore action in case it was changed                } else {                    intercepted = false;                }            } else {                // There are no touch targets and this action is not an initial down                // so this view group continues to intercept touches.                intercepted = true;            }            //按照冒泡法，将触摸事件传递给每个child处理            if (mFirstTouchTarget != null) {                // Dispatch to touch targets, excluding the new touch target if we already                // dispatched to it.  Cancel touch targets if necessary.                TouchTarget predecessor = null;                TouchTarget target = mFirstTouchTarget;                while (target != null) {                    final TouchTarget next = target.next;                    if (alreadyDispatchedToNewTouchTarget && target == newTouchTarget) {                        handled = true;                    } else {                        final boolean cancelChild = resetCancelNextUpFlag(target.child)                                || intercepted;                        //真正处理函数                        if (dispatchTransformedTouchEvent(ev, cancelChild,                                target.child, target.pointerIdBits)) {                            handled = true;                        }                        if (cancelChild) {                            if (predecessor == null) {                                mFirstTouchTarget = next;                            } else {                                predecessor.next = next;                            }                            target.recycle();                            target = next;                            continue;                        }                    }                    predecessor = target;                    target = next;                }            }        }        return handled;    }    private boolean dispatchTransformedTouchEvent(MotionEvent event, boolean cancel,            View child, int desiredPointerIdBits) {        // child == null意味着该parent已经调用完所有的child的dispatchTouchEvent        //所以从这里可以看出是child优先处理触摸事件的        if (child == null) {            handled = super.dispatchTouchEvent(transformedEvent);        } else {            handled = child.dispatchTouchEvent(transformedEvent);        }        return handled;    }    //这里的child如果仍就是一个ViewGroup，则和上面的逻辑一样。如果是一般的view，则    //直接调用view. dispatchTouchEvent    public boolean dispatchTouchEvent(MotionEvent event) {        if (onFilterTouchEventForSecurity(event)) {            //这个就是我们常使用view.setOnTouchListener调用保存下来的信息            ListenerInfo li = mListenerInfo;            if (li != null && li.mOnTouchListener != null && (mViewFlags & ENABLED_MASK) == ENABLED                    && li.mOnTouchListener.onTouch(this, event)) {                return true;            }            //view的默认处理，即调用onTouchEvent函数            if (onTouchEvent(event)) {                return true;            }        }        return false;   }    //TextView.java    @Override    public boolean onTouchEvent(MotionEvent event) {       //非TextView只会执行View. onTouchEvent,该函数是另一种将view和输入法绑定的调用       //而TextView会调用imm.showSoftInput会显示输入法        final boolean superResult = super.onTouchEvent(event);         if ((mMovement != null || onCheckIsTextEditor()) && isEnabled()                && mText instanceof Spannable && mLayout != null) {            if (touchIsFinished && (isTextEditable() || textIsSelectable)) {                // Show the IME, except when selecting in read-only text.                final InputMethodManager imm = InputMethodManager.peekInstance();                viewClicked(imm);                //这个是真正显示输入法的调用                if (!textIsSelectable && mEditor.mShowSoftInputOnFocus) {                    handled |= imm != null && imm.showSoftInput(this, 0);                }                handled = true;            }            if (handled) {                return true;            }        }        return superResult;   }   //View.java的onTouchEvent    public boolean onTouchEvent(MotionEvent event) {        final int viewFlags = mViewFlags;        if (((viewFlags & CLICKABLE) == CLICKABLE ||                (viewFlags & LONG_CLICKABLE) == LONG_CLICKABLE)) {            switch (event.getAction()) {                case MotionEvent.ACTION_UP:                    boolean prepressed = (mPrivateFlags & PFLAG_PREPRESSED) != 0;                    if ((mPrivateFlags & PFLAG_PRESSED) != 0 || prepressed) {                        // take focus if we don't have it already and we should in                        // touch mode.                        boolean focusTaken = false;                        //让view获得焦点                        if (isFocusable() && isFocusableInTouchMode() && !isFocused()) {                            focusTaken = requestFocus();                        }                    }                    break;            }            return true;        }        return false;    }    public boolean requestFocus(int direction, Rect previouslyFocusedRect) {        return requestFocusNoSearch(direction, previouslyFocusedRect);    }    private boolean requestFocusNoSearch(int direction, Rect previouslyFocusedRect) {        // 该view必须是可以获取焦点的        if ((mViewFlags & FOCUSABLE_MASK) != FOCUSABLE ||                (mViewFlags & VISIBILITY_MASK) != VISIBLE) {            return false;        }        // 这个检查得到对象大家可能经常用过，就是这个属性        //android:descendantFocusability=”blocksDescendants”，这个属性可以解决listView       //等容器类View没法获取点击事件问题,它的实现就在此，当父亲设置了这个属性        //子view就没法获取焦点了        if (hasAncestorThatBlocksDescendantFocus()) {            return false;        }        //获取焦点处理逻辑        handleFocusGainInternal(direction, previouslyFocusedRect);        return true;    }    void handleFocusGainInternal(int direction, Rect previouslyFocusedRect) {        if ((mPrivateFlags & PFLAG_FOCUSED) == 0) {            mPrivateFlags |= PFLAG_FOCUSED;            View oldFocus = (mAttachInfo != null) ? getRootView().findFocus() : null;            //由于当前焦点view没法知道旧的焦点view,没法告知旧的焦点view失去焦点            //所以必须叫父亲去做这个事情            if (mP arent != null) {                mParent.requestChildFocus(this, this);            }            //这个函数很重要，编辑类view(比如TextEditor)和普通view的差别就在此            //和输入法相关的处理也在此            onFocusChanged(true, direction, previouslyFocusedRect);            refreshDrawableState();        }   }   //基类View的处理：    protected void onFocusChanged(boolean gainFocus, int direction, Rect previouslyFocusedRect) {        InputMethodManager imm = InputMethodManager.peekInstance();        if (!gainFocus) {        } else if (imm != null && mAttachInfo != null                && mAttachInfo.mHasWindowFocus) {            //通知IMMS该view获得了焦点，到此，这后面的逻辑就和上面的window获            //得焦点导致view和输入法绑定的逻辑一样了            imm.focusIn(this);        }    }

输入法传递输入文本信息给view

输入法如何获得输入文本信息通信接口

从上面的输入法绑定的分析中可以知道，输入法其startInput接口被调用的时候获得了文本信息通信接口，这个通信接口是IInputContext的封装InputConnection，获取点如下：

    //InputMethodService.java    void doStartInput(InputConnection ic, EditorInfo attribute, boolean restarting) {        if (!restarting) {            doFinishInput();        }        mInputStarted = true;        //这个就是通信接口        mStartedInputConnection = ic;    }    public InputConnection getCurrentInputConnection() {        InputConnection ic = mStartedInputConnection;        if (ic != null) {            return ic;        }        return mInputConnection;    }

输入法如何传递文本信息给view

从上可见，输入法要传递文本信息时，肯定是先调用getCurrentInputConnection拿到接口，然后再传递信息，我们以pinyin输入法的实现来解释这个过程。

Pinyin输入法传递输入信息最后都会调用到sendKeyChar函数

    public void sendKeyChar(char charCode) {        switch (charCode) {            case '\n': // Apps may be listening to an enter key to perform an action                if (!sendDefaultEditorAction(true)) {                    sendDownUpKeyEvents(KeyEvent.KEYCODE_ENTER);                }                break;            default:                // Make sure that digits go through any text watcher on the client side.                if (charCode >= '0' && charCode <= '9') {                    sendDownUpKeyEvents(charCode - '0' + KeyEvent.KEYCODE_0);                } else {                    InputConnection ic = getCurrentInputConnection();                    if (ic != null) {                        //这个是真正传递信息到view的跨进程接口                        ic.commitText(String.valueOf((char) charCode), 1);                    }                }                break;        }    }

View接收输入文本信息

从上面可知，输入法端最后会通过InputConnection逻辑来传递文本信息，那程序view端的InputConnection是如何创建的呢？

    //InputMethodManager.java    boolean startInputInner(IBinder windowGainingFocus, int controlFlags, int softInputMode,        EditorInfo tba = new EditorInfo();        tba.packageName = view.getContext().getPackageName();        tba.fieldId = view.getId();        //由具体的view创建        InputConnection ic = view.onCreateInputConnection(tba);        return true;    }    //我们先看下textView会创建怎样的InputConnection？    //TextView.java    @Override    public InputConnection onCreateInputConnection(EditorInfo outAttrs) {      {            outAttrs.hintText = mHint;            if (mText instanceof Editable) {                //露面了，是 EditableInputConnection, textView作为参数传入                InputConnection ic = new EditableInputConnection(this);                return ic;            }        }        return null;    }

接下来肯定是EditableInputConnection 接收文本消息了

public class EditableInputConnection extends BaseInputConnection {    //该函数很重要，super.commitText会将字符添加到Editable里    @Override    public Editable getEditable() {        TextView tv = mTextView;        if (tv != null) {            return tv.getEditableText();        }        return null;    }    @Override    public boolean commitText(CharSequence text, int newCursorPosition) {        mTextView.resetErrorChangedFlag();        //调用父类的方法        boolean success = super.commitText(text, newCursorPosition);        mTextView.hideErrorIfUnchanged();        return success;    }}public class BaseInputConnection implements InputConnection {    public boolean commitText(CharSequence text, int newCursorPosition) {        replaceText(text, newCursorPosition, false);        sendCurrentText();        return true;    }    private void replaceText(CharSequence text, int newCursorPosition,boolean composing) {                //获取eidtorfinal Editable content = getEditable();if (content == null) {return;}beginBatchEdit();………………..                 //修改editorcontent.replace(a, b, text);        endBatchEdit();    }        private void sendCurrentText() {                Editable content = getEditable();        if (content != null) {            final int N = content.length();                        // 将输入文本模拟为为一个key事件，这样view就会更新内容了            KeyEvent event = new KeyEvent(SystemClock.uptimeMillis(),                    content.toString(), KeyCharacterMap.VIRTUAL_KEYBOARD, 0);            sendKeyEvent(event);            content.clear();        }     }     public boolean sendKeyEvent(KeyEvent event) {       //同ViewRootImpl有按键事件，到此为止就像是外接键盘的按键事件似的        synchronized (mIMM.mH) {            ViewRootImpl viewRootImpl = mTargetView != null ? mTargetView.getViewRootImpl() : null;            if (viewRootImpl == null) {                if (mIMM.mServedView != null) {                    viewRootImpl = mIMM.mServedView.getViewRootImpl();                }            }            if (viewRootImpl != null) {                //发送信息                viewRootImpl.dispatchKeyFromIme(event);            }        }

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Android输入法框架系统(下)