ViewRootImpl源码解读

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字数统计: 971字 | 阅读时长 ≈ 6分钟

主要功能

消息传递

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前置消息生成
hardWare&nativeCode -> 

InputEventReceiver(dispatchInputEvent)->

ViewRootImpl$WindowInputEventReceiver(dispatchInputEvent)->

ViewRootImpl(enqueueInputEvent) －>	

if processImmediately
 ViewRootImpl(doProcessInputEvents)  
else
 ViewRootImpl(scheduleProcessInputEvents)

KeyEvent

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Target:to find the focus one self or child.

get from QueuedInputEvent .....->

ViewRootImpl$ViewPostImeInputStage(onProcess)->

ViewRootImpl$ViewPostImeInputStage(processKeyEvent)->

PhoneWindow$DecorView(dispatchKeyEvent)->

Activity implenments Windows.CallBack(dispathcKeyEvent) ->

PhoneWindow$DecorView(superDispatchKeyEvent) ->

ViewGroup(dispatchKeyEvent) ->

View(dispatchKeyEvent) ->

KeyEvent(dispatch)
ViewGroup:dispatchKeyEvent
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@Override
    public boolean dispatchKeyEvent(KeyEvent event) {
        if (mInputEventConsistencyVerifier != null) {
            mInputEventConsistencyVerifier.onKeyEvent(event, 1);
        }

      //##important:here decide parent first and then child
      //## to find the focus one 
        if ((mPrivateFlags & (PFLAG_FOCUSED | PFLAG_HAS_BOUNDS))
                == (PFLAG_FOCUSED | PFLAG_HAS_BOUNDS)) {
            if (super.dispatchKeyEvent(event)) {
                return true;
            }
        } else if (mFocused != null && (mFocused.mPrivateFlags & PFLAG_HAS_BOUNDS)
                == PFLAG_HAS_BOUNDS) {
            if (mFocused.dispatchKeyEvent(event)) {
                return true;
            }
        }

        if (mInputEventConsistencyVerifier != null) {
            mInputEventConsistencyVerifier.onUnhandledEvent(event, 1);
        }
        return false;
    }
View:dispatchKeyEvent
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/**
  * Dispatch a key event to the next view on the focus path. This path runs
  * from the top of the view tree down to the currently focused view. If this
  * view has focus, it will dispatch to itself. Otherwise it will dispatch
  * the next node down the focus path. This method also fires any key
  * listeners.
  *
  * @param event The key event to be dispatched.
  * @return True if the event was handled, false otherwise.
  */
 public boolean dispatchKeyEvent(KeyEvent event) {
     if (mInputEventConsistencyVerifier != null) {
         mInputEventConsistencyVerifier.onKeyEvent(event, 0);
     }

     // Give any attached key listener a first crack at the event.
     //noinspection SimplifiableIfStatement
   // setOnKeyListener 
     ListenerInfo li = mListenerInfo;
     if (li != null && li.mOnKeyListener != null && (mViewFlags & ENABLED_MASK) == ENABLED
             && li.mOnKeyListener.onKey(this, event.getKeyCode(), event)) {
         return true;
     }

     if (event.dispatch(this, mAttachInfo != null
             ? mAttachInfo.mKeyDispatchState : null, this)) {
         return true;
     }

     if (mInputEventConsistencyVerifier != null) {
         mInputEventConsistencyVerifier.onUnhandledEvent(event, 0);
     }
     return false;
 }
Activity:dispatchKeyEvent
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/**
 * Called to process key events.  You can override this to intercept all
 * key events before they are dispatched to the window.  Be sure to call
 * this implementation for key events that should be handled normally.
 *
 * @param event The key event.
 *
 * @return boolean Return true if this event was consumed.
 */
public boolean dispatchKeyEvent(KeyEvent event) {
    onUserInteraction();

    // Let action bars open menus in response to the menu key prioritized over
    // the window handling it
    if (event.getKeyCode() == KeyEvent.KEYCODE_MENU &&
            mActionBar != null && mActionBar.onMenuKeyEvent(event)) {
        return true;
    }

  //##important:here decide the sequece ViewGroup View Activity;
    Window win = getWindow();
    if (win.superDispatchKeyEvent(event)) {
        return true;
    }
    View decor = mDecor;
    if (decor == null) decor = win.getDecorView();
  // at last 
    return event.dispatch(this, decor != null
            ? decor.getKeyDispatcherState() : null, this);
}

TouchEvent

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Sequence:dispatchTouchEvent,onInterceptTouchEvent,onTouchEvent ,U型传递

get from  QueueInputEvent....->
ViewRootImpl$ViewPostImeInputStage(processPointerEvent)->
View(dispatchPointerEvent)->
PhoneWindow$DecorView(dispatchTouchEvent)->
Activity implements Windows.CallBack:(dispatchTouchEvent)->
PhoneWindow$DecorView(superDispatchTouchEvent)->
ViewGroup(dispatchTouchEvent)->
View(dispatchTouchEvent)-> 
.........
U型传递图

ViewRootImpl_U1

总结：

  1. touch事件先子View后父View,key事件先父View后子View,Activity作为兜底方案
  2. 不论是touch事件还是key事件都是自顶向下分发的
  3. …….

与windowsManagerService通信

IWindowSession

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new ViewRootImpl ->
WindowManagerGlobal(getWindowSession)->
WindowManagerService(openSession) ->
......
Session

This class represents an active client session. There is generally one Session object per process that is interacting with the window manager.

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//## from WindowManagerService openSession
   @Override
  public IWindowSession openSession(IWindowSessionCallback callback, IInputMethodClient client,
          IInputContext inputContext) {
      if (client == null) throw new IllegalArgumentException("null client");
      if (inputContext == null) throw new IllegalArgumentException("null inputContext");
      Session session = new Session(this, callback, client, inputContext);
      return session;
  }

SurfaceSession

How to Create
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ActivityThread(handleResumeActivity) ->

WindowManagerGlobal(addView)->

ViewRootImpl(setView) ->

Session(addToDisplay)->

WindowManagerService(addWindow) ->

WindowState(attach) ->

Session(windowAddedLocked)->

new SurfaceSession

触发视图的更新

Activity的onCreate

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ActivityThread(handleLaunchActivity) -> 

ActivityThread performLaunchActivity ->

Instrumentation(callActivityOnCreate) ->

Activity(onCreate)

DecorView的建立

via setContentView 

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Activity (setContentView)->

PhoneWindow(setContentView)->

PhoneWindow(installDecor)->

PhoneWindow(generateDecor)->

new DecorView -> LayoutInflater .......

DecorView的添加

via onResume

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//## Surface create in ViewRootImpl but is Empty
//## surface filled data in outSurface.copyFrom(surfaceControl)

ActivityThread (handleResumeActivity) ->

WindowManagerGlobal(addView)->

ViewRootImpl(setView)->

......

ViewRootImpl(performTraversals)->

ViewRootImpl(relayoutWindow)-> 

Session(relayout)->

WindowManagerService(relayoutWindow)-> 

WindowStateAnimator createSurfaceLocked  outSurface.copyFrom(surfaceControl)->.....

AttachToWindow

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ActivityThread(handleResumeActivity)->
  
WindowManagerGlobal(addView)->
  
ViewRootImpl(setView)->
  
ViewRootImpl(requestLayout) ......->
  
ViewRootImpl(performTraversals)
[here  host.dispatchAttachedToWindow ,host.dispatchWindowVisibilityChanged ......onMeasure ,onLayout,onDraw....]->
  
......

DettachToWindow

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ActivityThread(handleDestroyActivity)->
  
WindowManagerImpl(removeViewImmediate)->
  
WindowManagerGlobal(removeView)->
  
WindowManagerGlobal(removeViewLocked)-> 
  
ViewRootImpl(die)->
  
ViewRootImpl(doDie)->
  
ViewRootImpl(dispatchDetachedFromWindow)->
  
View(dispatchDetachedFromWindow)->
  
......

其他

数据生命周期

attachInfo

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//##ViewRootImpl
//Create 
new ViewRootImpl->

new View.AttachInfo(mWindowSession, mWindow, display, this, mHandler, this)
  
  
//dispatch to children
dispatchAttachedToWindow

//destory
dispatchDetachedFromWindow[attachinfo=null]

viewParent

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//##ViewRootImpl

//dispatch to children  on dispatchAttachToWindow
assignParent(this)

//detory on dispatchDetachFromWindow
assignParent(null)