Android输入法框架系统(下)

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 &
AG_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 '
': // 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eidtor
        final Editable content = getEditable();
        if (content == null) {
            return;
        }

        beginBatchEdit();
        ………………..
                 //修改editor
        content.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);
            }
        }