View的繪製流程分析之二-Android對Window對象的管理機制分析

關於Window對象管理的相關類：

---

• ViewManager

• WindowManager

• WindowManagerImpl

• WindowManagerGlobal

• ViewParent

• ViewRootImpl

• ActvityThread

• WindowManagerService

---

Window是一個抽象類，具體實現類就是 PhoneWindow ！

一個Window是通過一個View來承載的，還對應一個ViewRootImpl！

訪問Window必須通過WindowManager來實現！

Window具體操作方法實現實在WindowManagerImpl類中，方法定義在ViewManager接口中！

public interface ViewManager
{    
    public void addView(View view, ViewGroup.LayoutParams params);
    public void updateViewLayout(View view, ViewGroup.LayoutParams params);
    public void removeView(View view);
}

• 1
• 2
• 3
• 4
• 5
• 6

ViewManager接口定義了三個函數，分別對應window的添加，更新和刪除！

---

addView

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

• 1
• 2
• 3
• 4
• 5

其實WindowManagerImpl也沒有做具體的操作，而是交給了 WindowManagerGlobal

在WindowManagerImpl類中進行了初始化

private final WindowManagerGlobal mGlobal = WindowManagerGlobal.getInstance();

• 1

WindowManagerGlobal.java

private WindowManagerGlobal() {
    }

    public static WindowManagerGlobal getInstance() {
        synchronized (WindowManagerGlobal.class) {
            if (sDefaultWindowManager == null) {
                sDefaultWindowManager = new WindowManagerGlobal();
            }
            return sDefaultWindowManager;
        }
    }

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11

很明顯看出這是個單例模式！

---

private final ArrayList<View> mViews = new ArrayList<View>();
private final ArrayList<ViewRootImpl> mRoots = new ArrayList<ViewRootImpl>();
private final ArrayList<WindowManager.LayoutParams> mParams =
            new ArrayList<WindowManager.LayoutParams>();
private final ArraySet<View> mDyingViews = new ArraySet<View>();

• 1
• 2
• 3
• 4
• 5
• 6

WindowManagerGlobal中有四個重要的集合！

• mViews集合存儲了所有window對應的View對象！

• mRoots集合存儲了所有window對應的ViewRootImpl對象

• mParams集合存儲了所有window對應的佈局參數

• mDyingViews集合存儲了所有正在被刪除的window對象

---

public void addView(View view, ViewGroup.LayoutParams params,
            Display display, Window parentWindow) {
        // 1. 驗證參數！
        if (view == null) {
            throw new IllegalArgumentException("view must not be null");
        }
        if (display == null) {
            throw new IllegalArgumentException("display must not be null");
        }
        if (!(params instanceof WindowManager.LayoutParams)) {
            throw new IllegalArgumentException("Params must be WindowManager.LayoutParams");
        }

        final WindowManager.LayoutParams wparams = (WindowManager.LayoutParams) params;
        if (parentWindow != null) {
            parentWindow.adjustLayoutParamsForSubWindow(wparams);
        } else {
            final Context context = view.getContext();
            if (context != null
                    && (context.getApplicationInfo().flags
                            & ApplicationInfo.FLAG_HARDWARE_ACCELERATED) != 0) {
                wparams.flags |= WindowManager.LayoutParams.FLAG_HARDWARE_ACCELERATED;
            }
        }

        ViewRootImpl root; // 一個ViewRootImpl對象
        View panelParentView = null; // 一個View對象

        synchronized (mLock) {
            // ...
            // 查找view對應的index
            int index = findViewLocked(view, false);
            if (index >= 0) {
                if (mDyingViews.contains(view)) {// 如果正在被刪除的集合包含該view，則執行ViewRootImpl.doDie()函數
                    mRoots.get(index).doDie();
                } else {
                    throw new IllegalStateException("View " + view
                            + " has already been added to the window manager.");
                }
           }

            // ... 

            // 創建ViewRootImpl對象
            root = new ViewRootImpl(view.getContext(), display);
            // 設置佈局參數
            view.setLayoutParams(wparams);

            // 添加view到集合中
            mViews.add(view);
            // 添加ViewRootImpl到集合中
            mRoots.add(root);
            // 添加wparams參數到集合中
            mParams.add(wparams);
        }

        try {
            // 將view設置到ViewRootImpl中！
            root.setView(view, wparams, panelParentView);
        } catch (RuntimeException e) {
            // 設置異常則移除view
            synchronized (mLock) {
                final int index = findViewLocked(view, false);
                if (index >= 0) {
                    removeViewLocked(index, true);
                }
            }
            throw e;
        }
    }

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11
• 12
• 13
• 14
• 15
• 16
• 17
• 18
• 19
• 20
• 21
• 22
• 23
• 24
• 25
• 26
• 27
• 28
• 29
• 30
• 31
• 32
• 33
• 34
• 35
• 36
• 37
• 38
• 39
• 40
• 41
• 42
• 43
• 44
• 45
• 46
• 47
• 48
• 49
• 50
• 51
• 52
• 53
• 54
• 55
• 56
• 57
• 58
• 59
• 60
• 61
• 62
• 63
• 64
• 65
• 66
• 67
• 68
• 69
• 70

函數最後通過ViewRootImpl.setView() 來完成window的添加過程！

在setView()內部調用了requestLayout()開啓了繪製流程！

View的繪製流程是由ViewRootImpl來完成的！

requestLayout(); 完成繪製流程之後，通過WindowSession來完成Window的添加過程！

public void setView(View view, WindowManager.LayoutParams attrs, View panelParentView) {
            // ...

            try {
                    mOrigWindowType = mWindowAttributes.type;
                    mAttachInfo.mRecomputeGlobalAttributes = true;
                    collectViewAttributes();
                    res = mWindowSession.addToDisplay(mWindow, mSeq, mWindowAttributes,
                            getHostVisibility(), mDisplay.getDisplayId(),
                            mAttachInfo.mContentInsets, mAttachInfo.mStableInsets,
                            mAttachInfo.mOutsets, mInputChannel);
                } catch (RemoteException e) {
                    mAdded = false;
                    mView = null;
                    mAttachInfo.mRootView = null;
                    mInputChannel = null;
                    mFallbackEventHandler.setView(null);
                    unscheduleTraversals();
                    setAccessibilityFocus(null, null);
                    throw new RuntimeException("Adding window failed", e);
                } finally {
                    if (restore) {
                        attrs.restore();
                    }
                }

            // ...
}

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11
• 12
• 13
• 14
• 15
• 16
• 17
• 18
• 19
• 20
• 21
• 22
• 23
• 24
• 25
• 26
• 27
• 28

mWindowSession是IWindowSession類型變量，它是一個Binder對象！

真正的實現者是 Session！

@Override
    public int addToDisplay(IWindow window, int seq, WindowManager.LayoutParams attrs,
            int viewVisibility, int displayId, Rect outContentInsets, Rect outStableInsets,
            Rect outOutsets, InputChannel outInputChannel) {
        return mService.addWindow(this, window, seq, attrs, viewVisibility, displayId,
                outContentInsets, outStableInsets, outOutsets, outInputChannel);
    }

• 1
• 2
• 3
• 4
• 5
• 6
• 7

這裏又通過WindowManagerService來實現window的添加，這樣window的添加事務就交給了WMS進行處理！

---

updateViewLayout

WindowMangerImpl.java

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

• 1
• 2
• 3
• 4
• 5

public void updateViewLayout(View view, ViewGroup.LayoutParams params) {
        // ...
        final WindowManager.LayoutParams wparams = (WindowManager.LayoutParams)params;
        // 設置新的佈局參數
        view.setLayoutParams(wparams); 

        synchronized (mLock) {
            int index = findViewLocked(view, true);
            ViewRootImpl root = mRoots.get(index);
            mParams.remove(index);
            mParams.add(index, wparams); // 更新mParams集合對應的值
            root.setLayoutParams(wparams, false); // 更新ViewRootImpl中的參數, false表示不是一個新的view
        }
    }

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11
• 12
• 13
• 14

ViewRooImpl.java

void setLayoutParams(WindowManager.LayoutParams attrs, boolean newView) {
        synchronized (this) {
            // ...

            if (newView) {
                mSoftInputMode = attrs.softInputMode;
                requestLayout();
            }

            //...

            mWindowAttributesChanged = true;
            scheduleTraversals();
        }
    }

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11
• 12
• 13
• 14
• 15

在這個函數裏面又調用了scheduleTraversals() 來重新進行測量，佈局，繪製流程！

---

removeView

在ViewManager接口中只有一種刪除函數：

public void removeView(View view);

• 1

但是在WindowManager接口中又增加了一種刪除view的方式：

public void removeViewImmediate(View view); // 立即刪除

• 1

這兩種方式，一種表示同步刪除，一種表示異步刪除！

但是兩者都會去調用 WindowManagerGlobal中的 removeView() 函數！

WindowManagerImpl.java

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

• 1
• 2
• 3
• 4

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

• 1
• 2
• 3
• 4

WindowManagerGlobal.java

public void removeView(View view, boolean immediate) {
        if (view == null) {
            throw new IllegalArgumentException("view must not be null");
        }

        synchronized (mLock) {
            // 查找要被刪除view的索引
            int index = findViewLocked(view, true);
            // 從mRoots這個集合中得到view對象
            View curView = mRoots.get(index).getView();
            // 執行刪除操作
            removeViewLocked(index, immediate);
            if (curView == view) {
                return;
            }

            throw new IllegalStateException("Calling with view " + view
                    + " but the ViewAncestor is attached to " + curView);
        }
    }

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11
• 12
• 13
• 14
• 15
• 16
• 17
• 18
• 19
• 20

removeView() 第二個參數表示是否立刻刪除~

private void removeViewLocked(int index, boolean immediate) {
        // 獲取view對應的ViewRootImpl對象
        ViewRootImpl root = mRoots.get(index);
        View view = root.getView();

        // ...
        // 調用View中的die()函數
        boolean deferred = root.die(immediate);
        if (view != null) {
            view.assignParent(null);
            if (deferred) { // 添加到正在被刪除的集合中
                mDyingViews.add(view);
            }
        }
    }

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11
• 12
• 13
• 14
• 15

ViewRootImpl.java

boolean die(boolean immediate) {
        // 立刻刪除時，直接執行doDie()函數完成真正的刪除操作！然後返回false
        if (immediate && !mIsInTraversal) {
            doDie();
            return false;
        }

        // ...
        // 異步刪除時，發送一個請求刪除的消息，然後直接返回true
        mHandler.sendEmptyMessage(MSG_DIE);
        return true;
    }

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11
• 12

其實在異步刪除時，handler處理的時候也是調用的doDie()函數來完成刪除！

case MSG_DIE:
   doDie();
   break;

• 1
• 2
• 3

ViewRootImpl.java

void doDie() {
        checkThread(); // 檢查線程, 很多地方都會調用這個函數！

        synchronized (this) {
            if (mRemoved) { // mRemoved默認是false，doDie()函數執行時變爲true
                return;
            }
            mRemoved = true;
            if (mAdded) { // 如果當前window對象應被添加到屏幕上！則需要回調detach函數
                dispatchDetachedFromWindow();
            }

            if (mAdded && !mFirst) {
                destroyHardwareRenderer(); // 停止硬件渲染

                if (mView != null) {
                    int viewVisibility = mView.getVisibility();
                    boolean viewVisibilityChanged = mViewVisibility != viewVisibility;
                    if (mWindowAttributesChanged || viewVisibilityChanged) { // 如果window屬性更改或者顯示方式改變

                        try {
                            if ((relayoutWindow(mWindowAttributes, viewVisibility, false)
                                    & WindowManagerGlobal.RELAYOUT_RES_FIRST_TIME) != 0) {
                                mWindowSession.finishDrawing(mWindow);
                            }
                        } catch (RemoteException e) {
                        }
                    }

                    mSurface.release(); // 釋放資源
                }
            }

            mAdded = false; // 狀態還原
        }
        WindowManagerGlobal.getInstance().doRemoveView(this);
    }

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11
• 12
• 13
• 14
• 15
• 16
• 17
• 18
• 19
• 20
• 21
• 22
• 23
• 24
• 25
• 26
• 27
• 28
• 29
• 30
• 31
• 32
• 33
• 34
• 35
• 36
• 37

WindowManagerGlobal.java

void doRemoveView(ViewRootImpl root) {
        synchronized (mLock) {
            final int index = mRoots.indexOf(root); 
            if (index >= 0) {
                mRoots.remove(index);// 從ViewRootImpl集合中刪除
                mParams.remove(index); //  刪除對應的參數
                final View view = mViews.remove(index); // 刪除對應的view
                mDyingViews.remove(view);// 從正在被刪除的集合中刪除view
            }
        }
        if (ThreadedRenderer.sTrimForeground && ThreadedRenderer.isAvailable()) {
            doTrimForeground();
        }
    }

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11
• 12
• 13
• 14

再來看看dispatchDetachedFromWindow()函數

void dispatchDetachedFromWindow() {
        if (mView != null && mView.mAttachInfo != null) {
            mAttachInfo.mTreeObserver.dispatchOnWindowAttachedChange(false);
            mView.dispatchDetachedFromWindow(); // 回調view的detach函數！方法內部會調用onDetachedFromWidow()函數 和 onDetachedFromWindowInternal()函數
        }

        // ...

        destroyHardwareRenderer();

        // ...

        mSurface.release();

        // ...
        try {
            mWindowSession.remove(mWindow);
        } catch (RemoteException e) {
        }

        // ...

        mDisplayManager.unregisterDisplayListener(mDisplayListener);

        unscheduleTraversals();
    }

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11
• 12
• 13
• 14
• 15
• 16
• 17
• 18
• 19
• 20
• 21
• 22
• 23
• 24
• 25
• 26

再次通過IPC方式調用remove()函數！

Session.java

public void remove(IWindow window) {
        mService.removeWindow(this, window);
    }

• 1
• 2
• 3

WMS.java

public void removeWindow(Session session, IWindow client) {
        synchronized(mWindowMap) {
            WindowState win = windowForClientLocked(session, client, false);
            if (win == null) {
                return;
            }
            removeWindowLocked(win);
        }
    }

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9

void removeWindowLocked(WindowState win) {
        removeWindowLocked(win, false);
    }

• 1
• 2
• 3

void removeWindowLocked(WindowState win, boolean keepVisibleDeadWindow) {
        win.mWindowRemovalAllowed = true;
        // ...

        boolean wasVisible = false;
        // ...

        removeWindowInnerLocked(win);
        // ...
    }

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10

removeWindowInnerLocked(win); 方法內部分析先暫停！！！

http://blog.csdn.net/crazy1235/article/details/72633389