Android 소스 읽기, View 그리기 프로세스 분석

1. View의 그리기 프로세스는 어디에서 시작되었습니까?
준비 지식:Activity의 시작 프로세스View의 그리기 입구는ActivityThread의handle ResumeActivity에서 볼 수 있습니다.

final void handleResumeActivity(IBinder token,
        boolean clearHide, boolean isForward, boolean reallyResume, int seq, String reason) {
    ActivityClientRecord r = mActivities.get(token);

    //              onReStart onStart  onResume    
    r = performResumeActivity(token, clearHide, reason);

    if (r != null) {
        final Activity a = r.activity;
    
        if (r.window == null && !a.mFinished && willBeVisible) {
            r.window = r.activity.getWindow();
            View decor = r.window.getDecorView();
            decor.setVisibility(View.INVISIBLE);
            ViewManager wm = a.getWindowManager();
            WindowManager.LayoutParams l = r.window.getAttributes();
            a.mDecor = decor;
            l.type = WindowManager.LayoutParams.TYPE_BASE_APPLICATION;
            l.softInputMode |= forwardBit;
            // ....      
            if (a.mVisibleFromClient) {
                if (!a.mWindowAdded) {
                    a.mWindowAdded = true;
                    //    View    ViewManager--》WindowManager--》WindowManagerImpl（     ）
                    // View             
                    wm.addView(decor, l);
                } 
            } 
        }          
    } 
}

4

View의 드로잉 프로세스는 ViewManager에서 수행됩니다.addView(View view, View Group. Layout Params params)라는 방법으로 시작합니다

2. ViewManager 클래스는 어디에서 생성됩니까?

1. ViewManager wm = a.getWindowManager();      Activity   

public WindowManager getWindowManager() {
    return mWindowManager;
}

// mWindowManager   attch       
final void attach(Context context, ActivityThread aThread,
        Instrumentation instr, IBinder token, int ident,
        Application application, Intent intent, ActivityInfo info,
        CharSequence title, Activity parent, String id,
        NonConfigurationInstances lastNonConfigurationInstances,
        Configuration config, String referrer, IVoiceInteractor voiceInteractor,
        Window window, ActivityConfigCallback activityConfigCallback) {
    attachBaseContext(context);

    mFragments.attachHost(null /*parent*/);

    mWindow = new PhoneWindow(this, window, activityConfigCallback);
    mWindow.setWindowControllerCallback(this);
    mWindow.setCallback(this);
    mWindow.setOnWindowDismissedCallback(this);
    mWindow.getLayoutInflater().setPrivateFactory(this);
    //            
    mWindow.setWindowManager(
            (WindowManager)context.getSystemService(Context.WINDOW_SERVICE),
            mToken, mComponent.flattenToString(),
            (info.flags & ActivityInfo.FLAG_HARDWARE_ACCELERATED) != 0);
    if (mParent != null) {
        mWindow.setContainer(mParent.getWindow());
    }
    //       ，      WindowManagerImpl   
    mWindowManager = mWindow.getWindowManager();
    mCurrentConfig = config;

    mWindow.setColorMode(info.colorMode);
}

public void setWindowManager(WindowManager wm, IBinder appToken, String appName,
        boolean hardwareAccelerated) {
    mAppToken = appToken;
    mAppName = appName;
    mHardwareAccelerated = hardwareAccelerated
            || SystemProperties.getBoolean(PROPERTY_HARDWARE_UI, false);
    if (wm == null) {
      //  ViewManager        ，        ：WindowManager
        wm = (WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE);
    }
    // WindowManagerImpl    new   
    mWindowManager = ((WindowManagerImpl)wm).createLocalWindowManager(this);
}

public WindowManagerImpl createLocalWindowManager(Window parentWindow) {
    return new WindowManagerImpl(mContext, parentWindow);
}

클래스 관계: 클래스 윈도 관리자 Impl은 윈도 관리자 인터페이스를 실현하고 윈도 관리자 인터페이스는 ViewManager 인터페이스를 계승한다.
3. WindowManagerImpl 클래스,addView 코드 보기

public final class WindowManagerImpl implements WindowManager {
    private final WindowManagerGlobal mGlobal = WindowManagerGlobal.getInstance();
    private final Context mContext;
    private final Window mParentWindow;

    private IBinder mDefaultToken;


    private WindowManagerImpl(Context context, Window parentWindow) {
        mContext = context;
        mParentWindow = parentWindow;
    }
    public WindowManagerImpl createLocalWindowManager(Window parentWindow) {
        return new WindowManagerImpl(mContext, parentWindow);
    }

    
    @Override
    public void addView(@NonNull View view, @NonNull ViewGroup.LayoutParams params) {
        applyDefaultToken(params);
        //      WindowManagerGlobal.addView  
        mGlobal.addView(view, params, mContext.getDisplay(), mParentWindow);
    }

    @Override
    public void updateViewLayout(@NonNull View view, @NonNull ViewGroup.LayoutParams params) {
        applyDefaultToken(params);
        mGlobal.updateViewLayout(view, params);
    }

    
    @Override
    public void removeView(View view) {
        mGlobal.removeView(view, false);
    }

    @Override
    public void removeViewImmediate(View view) {
        mGlobal.removeView(view, true);
    }

    @Override
    public void requestAppKeyboardShortcuts(
            final KeyboardShortcutsReceiver receiver, int deviceId) {
        IResultReceiver resultReceiver = new IResultReceiver.Stub() {
            @Override
            public void send(int resultCode, Bundle resultData) throws RemoteException {
                List result =
                        resultData.getParcelableArrayList(PARCEL_KEY_SHORTCUTS_ARRAY);
                receiver.onKeyboardShortcutsReceived(result);
            }
        };
        try {
            WindowManagerGlobal.getWindowManagerService()
                .requestAppKeyboardShortcuts(resultReceiver, deviceId);
        } catch (RemoteException e) {
        }
    }

    @Override
    public Display getDefaultDisplay() {
        return mContext.getDisplay();
    }
}

넷째, 윈도우 관리자 글로벌 클래스,addView 코드 보기

public void addView(View view, ViewGroup.LayoutParams params,
        Display display, Window parentWindow) {
    // ViewRootImpl    ViewParent     
    ViewRootImpl root;
    View panelParentView = null;

    synchronized (mLock) {
       
        //   ViewRootImpl
        root = new ViewRootImpl(view.getContext(), display);

        view.setLayoutParams(wparams);
        //        
        mViews.add(view);
        mRoots.add(root);
        mParams.add(wparams);

        // do this last because it fires off messages to start doing things
        try {
            // View         
            root.setView(view, wparams, panelParentView);
        } catch (RuntimeException e) {
            // BadTokenException or InvalidDisplayException, clean up.
            if (index >= 0) {
                removeViewLocked(index, true);
            }
            throw e;
        }
    }
}

5. ViewRootImpl 클래스, setView 코드 보기

public void setView(View view, WindowManager.LayoutParams attrs, View panelParentView) {
    synchronized (this) {
        if (mView == null) {
            mView = view;

            //    N   

            //     ，    
            requestLayout();
            
            //    N   
            
        }
    }
}

@Override
public void requestLayout() {
    if (!mHandlingLayoutInLayoutRequest) {
        //   UI  ，       View     。
        checkThread();
        mLayoutRequested = true;
        //        
        scheduleTraversals();
    }
}

void scheduleTraversals() {
    if (!mTraversalScheduled) {
        mTraversalScheduled = true;
        mTraversalBarrier = mHandler.getLooper().getQueue().postSyncBarrier();
        //     Handler      mTraversalRunnable  。
        //        mTraversalRunnable   Runnable   run()  
        mChoreographer.postCallback(
                Choreographer.CALLBACK_TRAVERSAL, mTraversalRunnable, null);
        if (!mUnbufferedInputDispatch) {
            scheduleConsumeBatchedInput();
        }
        notifyRendererOfFramePending();
        pokeDrawLockIfNeeded();
    }
}

6. TraversalRunnable 클래스,run () 코드 보기

final TraversalRunnable mTraversalRunnable = new TraversalRunnable();
final class TraversalRunnable implements Runnable {
    @Override
    public void run() {
        //     ViewRootImpl  doTraversal()
        doTraversal();
    }
}
 // ViewRootImpl      
void doTraversal() {
    if (mTraversalScheduled) {
        mTraversalScheduled = false;
        mHandler.getLooper().getQueue().removeSyncBarrier(mTraversalBarrier);

        if (mProfile) {
            Debug.startMethodTracing("ViewAncestor");
        }
        // View   、  、       
        performTraversals();

        if (mProfile) {
            Debug.stopMethodTracing();
            mProfile = false;
        }
    }
}
  // ViewRootImpl      
private void performTraversals() {
   
    // ...  N   

    //   View
    performMeasure(childWidthMeasureSpec, childHeightMeasureSpec);
    //   View
    performLayout(lp, mWidth, mHeight);
    //   View
    performDraw();
    
    // ...  N   
}

7.perform Measure,perform Layout,perform Draw 세 가지 방법을 총괄
1. perform Measure(child Width Measure Spec,child Height Measure Spec) --> mView.measure(childWidthMeasureSpec, childHeightMeasureSpec) --> onMeasure(widthMeasureSpec, heightMeasureSpec);

1. performMeasure                  。
2.   ViewGrop，       View   ，     View               。
3.   View，       View             。

2. perform Layout(lp, mWidth, mHeight) -->> host.layout(0, 0, host.getMeasuredWidth(), host.getMeasuredHeight()); -->> onLayout(changed, l, t, r, b);

1.        。
2.   ViewGrop，   View，     View  child.layout(l,t,r,b)     View。
3.   View    。

3. performDraw()-->drawSoftware()-->mView.draw(canvas); --> drawBackground(canvas);-->onDraw(canvas);--> dispatchDraw(canvas);--> onDrawForeground(canvas);

1.         View
2.           ，   View  ViewGrop         。
3.   ViewGrop，   dispatchDraw  ，          View draw()  ，    View。
4.   View，    onDraw(canvas)     。