Window 和 WindowManager

作者: 接地气的二呆 | 来源:发表于2016-09-17 15:45 被阅读526次

    概述

    window

    • window 是一个抽象类,具体实现是PhoneWindow
    • window 也是一个抽象的概念,每个 window 内对应这一个 DecorView 和一个 ViewRootImplwindowDecorView 通过ViewRootImpl联系。

    WindowManager

    WindowManager 是 外界访问 Window 的入口

    WindowManagerService

    window 的具体实现位于WindowManagerService中,WindowManagerWindowManagerService的交互是一个 IPC 的过程,

    源码分析

    window 的添加、删除、更新 view 均是通过WindowManager来完成的,而WindowManager继承了 ViewManager的接口

    /** Interface to let you add and remove child views to an Activity. To get an instance
      * of this class, call {@link android.content.Context#getSystemService(java.lang.String) Context.getSystemService()}.
      */
    public interface ViewManager
    {
        /**
         * Assign the passed LayoutParams to the passed View and add the view to the window.
         * <p>Throws {@link android.view.WindowManager.BadTokenException} for certain programming
         * errors, such as adding a second view to a window without removing the first view.
         * <p>Throws {@link android.view.WindowManager.InvalidDisplayException} if the window is on a
         * secondary {@link Display} and the specified display can't be found
         * (see {@link android.app.Presentation}).
         * @param view The view to be added to this window.
         * @param params The LayoutParams to assign to view.
         */
        public void addView(View view, ViewGroup.LayoutParams params);
        public void updateViewLayout(View view, ViewGroup.LayoutParams params);
        public void removeView(View view);
    }
    
    

    对应的三个方法,继续看WindowManager对应的具体实现类,WindowManagerImple

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

    可以看到,具体的方法均交给WindowManagerGlobal来处理,而WindowManagerGlobal则以工程模式提供了自己的实例

    private final WindowManagerGlobal mGlobal = WindowManagerGlobal.getInstance();
    

    看看``中比较重要的几个成员变量

        private final ArrayList<View> mViews = new ArrayList<View>();//所有 window 对应的 DecorView
        private final ArrayList<ViewRootImpl> mRoots = new ArrayList<ViewRootImpl>();////所有 window 对应的 ViewRootImpl
        private final ArrayList<WindowManager.LayoutParams> mParams =
                new ArrayList<WindowManager.LayoutParams>(); //所有 window 对应的 WindowManager.LayoutParams
        private final ArraySet<View> mDyingViews = new ArraySet<View>();//所有 window 对应需要删除的 view
    

    添加过程

    具体分析WindowManagerGlobaladdview

     public void addView(View view, ViewGroup.LayoutParams params,
                Display display, Window parentWindow) {
            //首先检查了参数,并抛出对应的异常
            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 {
                // If there's no parent, then hardware acceleration for this view is
                // set from the application's hardware acceleration setting.
                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;
            View panelParentView = null;
    
            synchronized (mLock) {
                // Start watching for system property changes.
                if (mSystemPropertyUpdater == null) {
                    mSystemPropertyUpdater = new Runnable() {
                        @Override public void run() {
                            synchronized (mLock) {
                                for (int i = mRoots.size() - 1; i >= 0; --i) {
                                    mRoots.get(i).loadSystemProperties();
                                }
                            }
                        }
                    };
                    SystemProperties.addChangeCallback(mSystemPropertyUpdater);
                }
    
    //通过findViewLocked找到 view 对应的 index
                int index = findViewLocked(view, false);
                if (index >= 0) {
                //如果找到了,说明这个 view 已经被添加进来了
                    if (mDyingViews.contains(view)) {
                    //这个 view 是需要删除的话,那么不用管直接用doDie 删除
                        // Don't wait for MSG_DIE to make it's way through root's queue.
                        mRoots.get(index).doDie();
                    } else {
                    //说明这个 view 已经被添加进来了,抛出异常
                        throw new IllegalStateException("View " + view
                                + " has already been added to the window manager.");
                    }
                    // The previous removeView() had not completed executing. Now it has.
                }
    
                // If this is a panel window, then find the window it is being
                // attached to for future reference.
                if (wparams.type >= WindowManager.LayoutParams.FIRST_SUB_WINDOW &&
                        wparams.type <= WindowManager.LayoutParams.LAST_SUB_WINDOW) {
                    final int count = mViews.size();
                    for (int i = 0; i < count; i++) {
                    //找到对应的 window
                        if (mRoots.get(i).mWindow.asBinder() == wparams.token) {
                            panelParentView = mViews.get(i);
                        }
                    }
                }
    
                root = new ViewRootImpl(view.getContext(), display);
    
                view.setLayoutParams(wparams);
    //将得DecorView viewimpl params 都加入到 list 中
                mViews.add(view);
                mRoots.add(root);
                mParams.add(wparams);
            }
    
            // do this last because it fires off messages to start doing things
            try {
            //这个重要,通过 viewrootImpl 的 setview 方法来刷新 view
                root.setView(view, wparams, panelParentView);
            } catch (RuntimeException e) {
                // BadTokenException or InvalidDisplayException, clean up.
                synchronized (mLock) {
                    final int index = findViewLocked(view, false);
                    if (index >= 0) {
                        removeViewLocked(index, true);
                    }
                }
                throw e;
            }
        }
    

    setview 的方法比较长,看其中比较重要的几个方法
    requestLayout();

        @Override
        public void requestLayout() {
            if (!mHandlingLayoutInLayoutRequest) {
                checkThread();
                mLayoutRequested = true;
                scheduleTraversals();
            }
        }
    
    

    scheduleTraversals 是 view 开始绘制的入口

    继续往下看 window 的添加过程

    mOrigWindowType = mWindowAttributes.type;
                        mAttachInfo.mRecomputeGlobalAttributes = true;
                        collectViewAttributes();
                        res = mWindowSession.addToDisplay(mWindow, mSeq, mWindowAttributes,
                                getHostVisibility(), mDisplay.getDisplayId(),
                                mAttachInfo.mContentInsets, mAttachInfo.mStableInsets,
                                mAttachInfo.mOutsets, mInputChannel);
    

    IWindowSession是一个 binder 对象。最终会调用到windowManagerService中的方法

    删除过程

    具体分析WindowManagerGlobalremoveview

     public void removeView(View view, boolean immediate) {
            if (view == null) {
                throw new IllegalArgumentException("view must not be null");
            }
    
            synchronized (mLock) {
           //找到对应的 index ,再removeViewLocked
                int index = findViewLocked(view, true);
                View curView = mRoots.get(index).getView();
                removeViewLocked(index, immediate);
                if (curView == view) {
                    return;
                }
    
                throw new IllegalStateException("Calling with view " + view
                        + " but the ViewAncestor is attached to " + curView);
            }
        }
        
        
           private void removeViewLocked(int index, boolean immediate) {
            ViewRootImpl root = mRoots.get(index);
            View view = root.getView();
    
            if (view != null) {
                InputMethodManager imm = InputMethodManager.getInstance();
                if (imm != null) {
                    imm.windowDismissed(mViews.get(index).getWindowToken());
                }
            }
    //        ViewRootImpl 的 die 方法
            boolean deferred = root.die(immediate);
            if (view != null) {
                view.assignParent(null);
                if (deferred) {
                    mDyingViews.add(view);
                }
            }
        }
        
        //die 方法比较简单,就是发送了一个 message,最后在处理 message 的时候调用了doDie
            boolean die(boolean immediate) {
            // Make sure we do execute immediately if we are in the middle of a traversal or the damage
            // done by dispatchDetachedFromWindow will cause havoc on return.
            if (immediate && !mIsInTraversal) {
                doDie();
                return false;
            }
    
            if (!mIsDrawing) {
                destroyHardwareRenderer();
            } else {
                Log.e(TAG, "Attempting to destroy the window while drawing!\n" +
                        "  window=" + this + ", title=" + mWindowAttributes.getTitle());
            }
            mHandler.sendEmptyMessage(MSG_DIE);
            return true;
        }
        
        
         void doDie() {
            checkThread();
            if (LOCAL_LOGV) Log.v(TAG, "DIE in " + this + " of " + mSurface);
            synchronized (this) {
                if (mRemoved) {
                    return;
                }
                mRemoved = true;
                if (mAdded) {
                //这里做了一些资源的回抽,停动画等
                    dispatchDetachedFromWindow();
                }
    
                if (mAdded && !mFirst) {
                    destroyHardwareRenderer();
    
                    if (mView != null) {
                        int viewVisibility = mView.getVisibility();
                        boolean viewVisibilityChanged = mViewVisibility != viewVisibility;
                        if (mWindowAttributesChanged || viewVisibilityChanged) {
                            // If layout params have been changed, first give them
                            // to the window manager to make sure it has the correct
                            // animation info.
                            try {
                                if ((relayoutWindow(mWindowAttributes, viewVisibility, false)
                                        & WindowManagerGlobal.RELAYOUT_RES_FIRST_TIME) != 0) {
                                    mWindowSession.finishDrawing(mWindow);
                                }
                            } catch (RemoteException e) {
                            }
                        }
    
                        mSurface.release();
                    }
                }
    
                mAdded = false;
            }
            //在其中清理 那些成员 list 变量
            WindowManagerGlobal.getInstance().doRemoveView(this);
        }
        
        
    

    更新过程

     public void updateViewLayout(View view, ViewGroup.LayoutParams params) {
            if (view == null) {
                throw new IllegalArgumentException("view must not be null");
            }
            if (!(params instanceof WindowManager.LayoutParams)) {
                throw new IllegalArgumentException("Params must be WindowManager.LayoutParams");
            }
    
            final WindowManager.LayoutParams wparams = (WindowManager.LayoutParams)params;
    
            view.setLayoutParams(wparams);
    
            synchronized (mLock) {
            //删除旧的 param 更新成新的 param
                int index = findViewLocked(view, true);
                ViewRootImpl root = mRoots.get(index);
                mParams.remove(index);
                mParams.add(index, wparams);
                //通过 viewrootImpl 来刷新 view
                root.setLayoutParams(wparams, false);
            }
        }
    

    拓展阅读 window、Activity、DecorView、ViewRoot关系

    参考

    http://gold.xitu.io/entry/571338c7c4c9710054cea455
    http://www.jianshu.com/p/687010ccad66

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