一、概述
这次开始到了WindowManagerService(WMS),你可以把它看做一个WindowManager,只不过呢,属于系统服务进程(system_server)中的一员,和应用不在同一进程,所以涉及了一些跨进程通信的内容,如果不清楚的可以去补一下Binder通信机制。这些不是重点,这次重点接着之前没讲完的addToDisplayAsUser。
二、WMS
关于WMS启动的过程,之后会和AMS(ATMS)文章中一起讲解。如果已经有了解Android特有的跨进程通信方式Binder的基础,不难知道WMS是一个Binder对象,这对之后的讲解有点帮助。
2.1 addToDisplay
上篇Window的文章不知道大家还有没有印象mWindowSession#addToDisplayAsUser,这里的Session是通过WindowManagerGlobal#getWindowSession提供的binder对象,帮助我们完成跨进程通信。
//WindowManagerGlobal.java@UnsupportedAppUsagepublic static IWindowManager getWindowManagerService() {synchronized (WindowManagerGlobal.class) {if (sWindowManagerService == null) {sWindowManagerService = IWindowManager.Stub.asInterface(ServiceManager.getService("window"));try {if (sWindowManagerService != null) {ValueAnimator.setDurationScale(sWindowManagerService.getCurrentAnimatorScale());sUseBLASTAdapter = sWindowManagerService.useBLAST();}} catch (RemoteException e) {throw e.rethrowFromSystemServer();}}return sWindowManagerService;}}@UnsupportedAppUsagepublic static IWindowSession getWindowSession() {synchronized (WindowManagerGlobal.class) {if (sWindowSession == null) {try {// Emulate the legacy behavior. The global instance of InputMethodManager// was instantiated here.// TODO(b/116157766): Remove this hack after cleaning up @UnsupportedAppUsageInputMethodManager.ensureDefaultInstanceForDefaultDisplayIfNecessary();IWindowManager windowManager = getWindowManagerService();sWindowSession = windowManager.openSession(new IWindowSessionCallback.Stub() {@Overridepublic void onAnimatorScaleChanged(float scale) {ValueAnimator.setDurationScale(scale);}});} catch (RemoteException e) {throw e.rethrowFromSystemServer();}}return sWindowSession;}}
这段代码很长,但是很简单,目的是请求服务端的WindowSession对象,即服务端的binder对象。我们看它是怎么做的。首先先通过IPC通信方式获取WMS,之前说过这也是一个binder对象。然后借助WMS的openSession拿到服务端的WindowSession对象。这样做的好处是什么呢?将两次binder通信简化成了一次binder通信,优化了跨进程通信的效率。
服务端的WindowSession对象是一个叫做Session的类。
既然已经进入Session这个类,我们直接来看一下addToDisplayAsUser做了什么。
//Session.java@Overridepublic int addToDisplay(IWindow window, WindowManager.LayoutParams attrs,int viewVisibility, int displayId, @InsetsType int requestedVisibleTypes,InputChannel outInputChannel, InsetsState outInsetsState,InsetsSourceControl.Array outActiveControls, Rect outAttachedFrame,float[] outSizeCompatScale) {return mService.addWindow(this, window, attrs, viewVisibility, displayId,UserHandle.getUserId(mUid), requestedVisibleTypes, outInputChannel, outInsetsState,outActiveControls, outAttachedFrame, outSizeCompatScale);}@Overridepublic int addToDisplayAsUser(IWindow window, WindowManager.LayoutParams attrs,int viewVisibility, int displayId, int userId, @InsetsType int requestedVisibleTypes,InputChannel outInputChannel, InsetsState outInsetsState,InsetsSourceControl.Array outActiveControls, Rect outAttachedFrame,float[] outSizeCompatScale) {return mService.addWindow(this, window, attrs, viewVisibility, displayId, userId,requestedVisibleTypes, outInputChannel, outInsetsState, outActiveControls,outAttachedFrame, outSizeCompatScale);}
它调用了内部的addToDisplay方法,一般我会把这种行为相同,但是命名有些许不同的方法叫做衍生方法。这里面的mService就是WMS,因为它们属于同一个进程,所以这里的调用已经不是跨进程通信了。并且调用了WMS#addWindow方法。
上面跟了一大段,我们发现现在才是真正进入了WMS,可见系统源码对于职责的封装不可谓是不严格啊,我们继续分析。
//WindowManagerService.javapublic int addWindow(Session session, IWindow client, LayoutParams attrs, int viewVisibility,int displayId, int requestUserId, @InsetsType int requestedVisibleTypes,InputChannel outInputChannel, InsetsState outInsetsState,InsetsSourceControl.Array outActiveControls, Rect outAttachedFrame,float[] outSizeCompatScale) {...//获取屏幕内容对象,根据屏幕id(一屏多显可能也会有多个id)final DisplayContent displayContent = getDisplayContentOrCreate(displayId, attrs.token);...//一个window集合,保存的key是ViewRootImpl$w的binder对象(也可以理解为是window的binder对象)if (mWindowMap.containsKey(client.asBinder())) {ProtoLog.w(WM_ERROR, "Window %s is already added", client);return WindowManagerGlobal.ADD_DUPLICATE_ADD;}...//创建WindowState,服务端管理的window,记录了window全部信息
final WindowState win = new WindowState(this, session, client, token, parentWindow,appOp[0], attrs, viewVisibility, session.mUid, userId,session.mCanAddInternalSystemWindow);...win.attach();//添加到map集合中,key是客户端w的binder对象,value是WindwoStatemWindowMap.put(client.asBinder(), win);win.initAppOpsState();...//WindowState拿到token添加当前的WindowState进去,双向绑定win.mToken.addWindow(win);
由于WMS#addWindow篇幅很多,省略了很多细节之后看上去就清楚多了。重要的事情注解都有说明:
- 通过DisplayContent获取token
- 根据客户端window创建WindowState对象,保存Window有关的所有信息
- 把WindowState缓存到WindowMap集合中,key是客户端的w的binder对象
- 将WindowState和token双向绑定
关于ViewRootImpl#setView中的关于WMS#addToDisplayAsUser的逻辑我们就分析完了。这样一趟分析下来,发现其实也没有做多少事,但是有一点好奇的不知道大家有没有注意到,方法是setView,而addToDisplayAsUser只是在WMS层创建了一个WindowState对象进行管控,并没有对window或者view的操作和绘制。
2.2 relayoutWindow
在上一篇文章中Android基础知识之Window(二)我们有提到过performTraversals这个方法,是准备遍历开始绘制view的,在执行perfromMeasure之前,也就是最早的测量阶段前,还会调用一个方法relayoutWindow,我们在来看一下。
//ViewRootImpl.javaprivate int relayoutWindow(WindowManager.LayoutParams params, int viewVisibility,boolean insetsPending) throws RemoteException {...relayoutResult = mWindowSession.relayout(mWindow, params,requestedWidth, requestedHeight, viewVisibility,insetsPending ? WindowManagerGlobal.RELAYOUT_INSETS_PENDING : 0, mRelayoutSeq,mLastSyncSeqId, mTmpFrames, mPendingMergedConfiguration, mSurfaceControl,mTempInsets, mTempControls, mRelayoutBundle);...
其实这个有一个relayout和relayoutAsync的方法,两个在Session中都会调用到同一个方法,这里就不过多展示代码了。像之前讲的一样,Session也是借助WMS#relayoutWindow来处理的。
//WMS
public int relayoutWindow(Session session, IWindow client, LayoutParams attrs,int requestedWidth, int requestedHeight, int viewVisibility, int flags, int seq,int lastSyncSeqId, ClientWindowFrames outFrames,MergedConfiguration outMergedConfiguration, SurfaceControl outSurfaceControl,InsetsState outInsetsState, InsetsSourceControl.Array outActiveControls,Bundle outSyncIdBundle) {if (outActiveControls != null) {outActiveControls.set(null);}...//根据之前管理的WindowMap取出对应的WindowStatefinal WindowState win = windowForClientLocked(session, client, false);...//这个值是ViewRootImpl传下来的,根据内部mView是可见,设置请求的大小if (viewVisibility != View.GONE) {win.setRequestedSize(requestedWidth, requestedHeight);}...flagChanges = win.mAttrs.flags ^ attrs.flags;privateFlagChanges = win.mAttrs.privateFlags ^ attrs.privateFlags;//更新窗口的LayoutParamsattrChanges = win.mAttrs.copyFrom(attrs);...//给WMS管理的WindowState设置是否可见状态win.setViewVisibility(viewVisibility)...// Create surfaceControl before surface placement otherwise layout will be skipped// (because WS.isGoneForLayout() is true when there is no surface.if (shouldRelayout && outSurfaceControl != null) {try {//根据ViewRootImpl的SurfaceControl创建WMS的SurfaceControlresult = createSurfaceControl(outSurfaceControl, result, win, winAnimator);} catch (Exception e) {displayContent.getInputMonitor().updateInputWindowsLw(true /*force*/);ProtoLog.w(WM_ERROR,"Exception thrown when creating surface for client %s (%s). %s",client, win.mAttrs.getTitle(), e);Binder.restoreCallingIdentity(origId);return 0;}}...//刷新界面和更新焦点// We may be deferring layout passes at the moment, but since the client is interested// in the new out values right now we need to force a layout.mWindowPlacerLocked.performSurfacePlacement(true /* force */);...if (focusMayChange) {if (updateFocusedWindowLocked(UPDATE_FOCUS_NORMAL, true /*updateInputWindows*/)) {imMayMove = false;}}}
有负责取出之前创建WindowState、DisplayContent等对象;有设置可见状态;有更新窗口参数,请求窗口大小;然后创建WindowSurfaceControl对象。
createSurfaceControl
//WMSprivate int createSurfaceControl(SurfaceControl outSurfaceControl, int result,WindowState win, WindowStateAnimator winAnimator) {if (!win.mHasSurface) {result |= RELAYOUT_RES_SURFACE_CHANGED;}WindowSurfaceController surfaceController;try {Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER, "createSurfaceControl");surfaceController = winAnimator.createSurfaceLocked();} finally {Trace.traceEnd(TRACE_TAG_WINDOW_MANAGER);}if (surfaceController != null) {surfaceController.getSurfaceControl(outSurfaceControl);ProtoLog.i(WM_SHOW_TRANSACTIONS, "OUT SURFACE %s: copied", outSurfaceControl);} else {// For some reason there isn't a surface. Clear the// caller's object so they see the same state.ProtoLog.w(WM_ERROR, "Failed to create surface control for %s", win);outSurfaceControl.release();}return result;}
可以看到,应用上层传下来的是自己创建的outSurfaceControl,但是在WMS中,会创建一个SurfaceController,叫做WindowSurfaceController,内部也会创建一个SurfaceControl,然后把SurfaceControl的一些状态拷贝给outSurfaceControl。
//WindowStateAnimator.javaWindowSurfaceController createSurfaceLocked() {final WindowState w = mWin;if (mSurfaceController != null) {return mSurfaceController;}//设置是否有surface的标志为falsew.setHasSurface(false);ProtoLog.i(WM_DEBUG_ANIM, "createSurface %s: mDrawState=DRAW_PENDING", this);//重置绘制状态resetDrawState();...//创建WindowSurfaceControllermSurfaceController = new WindowSurfaceController(attrs.getTitle().toString(), format,flags, this, attrs.type);mSurfaceController.setColorSpaceAgnostic(w.getPendingTransaction(),(attrs.privateFlags & LayoutParams.PRIVATE_FLAG_COLOR_SPACE_AGNOSTIC) != 0);//SurfaceController创建好了,设置是否有surface的标志为truew.setHasSurface(true);...
这里我们先忽略一下WindowStateAnimator的创建过程,只需要知道,在创建上一篇文章中讲到的创建WindowState的过程中,会判断是否有Animator,没有则直接创建一个WindowStateAnimator对象,并让WindowState持有。而这段代码中,重点是当创建SurfaceController之后,才会把hasSurface设置为true。
我们再来看看WindowPlacerLocked#performSurfacePlacement方法,执行surface位置摆放,即Window显示位置和大小。
//WindowSurfacePlacer.java
private void performSurfacePlacementLoop() {...try {mService.mRoot.performSurfacePlacement();mInLayout = false;if (mService.mRoot.isLayoutNeeded()) {if (++mLayoutRepeatCount < 6) {requestTraversal();} else {Slog.e(TAG, "Performed 6 layouts in a row. Skipping");mLayoutRepeatCount = 0;}} else {mLayoutRepeatCount = 0;}if (mService.mWindowsChanged && !mService.mWindowChangeListeners.isEmpty()) {mService.mH.removeMessages(REPORT_WINDOWS_CHANGE);mService.mH.sendEmptyMessage(REPORT_WINDOWS_CHANGE);}} catch (RuntimeException e) {mInLayout = false;Slog.wtf(TAG, "Unhandled exception while laying out windows", e);}...
}
核心代码就是这一段,mService.mRoot是WMS中的RootWindowContainer,调用它的performSurfacePlacement执行表面放置操作。
void performSurfacePlacementNoTrace() {...//获取WindowSurfacePlacer,是一个单例final WindowSurfacePlacer surfacePlacer = mWmService.mWindowPlacerLocked;if (SHOW_LIGHT_TRANSACTIONS) {Slog.i(TAG,">>> OPEN TRANSACTION performLayoutAndPlaceSurfaces");}Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER, "applySurfaceChanges");//开启surface处理mWmService.openSurfaceTransaction();try {//开始处理surface变化的处理applySurfaceChangesTransaction();} catch (RuntimeException e) {Slog.wtf(TAG, "Unhandled exception in Window Manager", e);} finally {//关闭surface处理mWmService.closeSurfaceTransaction("performLayoutAndPlaceSurfaces");Trace.traceEnd(TRACE_TAG_WINDOW_MANAGER);if (SHOW_LIGHT_TRANSACTIONS) {Slog.i(TAG,"<<< CLOSE TRANSACTION performLayoutAndPlaceSurfaces");}}...
}
我们继续看看applySurfaceChangesTransaction,对surface变化处理做了什么。
//RootWindowContainer.javaprivate void applySurfaceChangesTransaction() {// TODO(multi-display): Support these features on secondary screens.final DisplayContent defaultDc = mDefaultDisplay;final DisplayInfo defaultInfo = defaultDc.getDisplayInfo();...// 也就是这个WindowContainer的一系列子windowContainer的集合final int count = mChildren.size();for (int j = 0; j < count; ++j) {//获取到这个WindowContainer对应的DisplayContentfinal DisplayContent dc = mChildren.get(j);//displaycontent执行surface变化的处理dc.applySurfaceChangesTransaction();}// Give the display manager a chance to adjust properties like display rotation if it needs to.mWmService.mDisplayManagerInternal.performTraversal(t);if (t != defaultDc.mSyncTransaction) {SurfaceControl.mergeToGlobalTransaction(t);}}
通过遍历WindowContainer来获取DisplayContent,对每个DisplayContent执行surface变化的任务。之前有说过,DisplayContent这个对象创建是通过Display模块提供的DisplayId,而这个id一般情况是一个屏幕对应一个,除非有创建虚拟屏幕。
//DisplayContent.java
// TODO: Super unexpected long method that should be broken down...
void applySurfaceChangesTransaction() {...// Perform a layout, if needed.performLayout(true /* initial */, false /* updateInputWindows */);pendingLayoutChanges = 0;Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER, "applyPostLayoutPolicy");try {mDisplayPolicy.beginPostLayoutPolicyLw();forAllWindows(mApplyPostLayoutPolicy, true /* traverseTopToBottom */);mDisplayPolicy.finishPostLayoutPolicyLw();} finally {Trace.traceEnd(TRACE_TAG_WINDOW_MANAGER);}mInsetsStateController.onPostLayout();mTmpApplySurfaceChangesTransactionState.reset();Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER, "applyWindowSurfaceChanges");try {forAllWindows(mApplySurfaceChangesTransaction, true /* traverseTopToBottom */);} finally {Trace.traceEnd(TRACE_TAG_WINDOW_MANAGER);}prepareSurfaces();...
}
这里两个重要的方法一个performLayout,这个之后进入分析,还有一个forAllWindows,传入的是一个mApplyPostLayoutPolicy的回调方法,它是遍历所有window,并对每个window应用Surface变化的事务。
//DisplayContent.javavoid performLayout(boolean initial, boolean updateInputWindows) {Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER, "performLayout");try {performLayoutNoTrace(initial, updateInputWindows);} finally {Trace.traceEnd(TRACE_TAG_WINDOW_MANAGER);}}private void performLayoutNoTrace(boolean initial, boolean updateInputWindows) {if (!isLayoutNeeded()) {return;}clearLayoutNeeded();if (DEBUG_LAYOUT) {Slog.v(TAG, "-------------------------------------");Slog.v(TAG, "performLayout: dw=" + mDisplayInfo.logicalWidth+ " dh=" + mDisplayInfo.logicalHeight);}int seq = mLayoutSeq + 1;if (seq < 0) seq = 0;mLayoutSeq = seq;mTmpInitial = initial;// First perform layout of any root windows (not attached to another window).forAllWindows(mPerformLayout, true /* traverseTopToBottom */);// Now perform layout of attached windows, which usually depend on the position of the// window they are attached to. XXX does not deal with windows that are attached to windows// that are themselves attached.forAllWindows(mPerformLayoutAttached, true /* traverseTopToBottom */);// Window frames may have changed. Tell the input dispatcher about it.mInputMonitor.setUpdateInputWindowsNeededLw();if (updateInputWindows) {mInputMonitor.updateInputWindowsLw(false /*force*/);}}
这里的两个forAllWindow,同样是遍历了所有的window,只不过它们的回调方法不同,一个处理遍历所有window,让它们应用Layout的事务,一个遍历所有window,让它们应用LayoutAttach的事务。这几个回调方法,我们就不继续跟了,想要了解的可以自行查看一下源码。
总结就是先遍历所有窗口,对每个窗口应用表面变化,接着对每个根窗口执行布局操作,再接着对每个附加窗口(依赖其他窗口位置的窗口)执行布局操作。最后根据updateInputWindows的状态,更新input window(输入窗口)。
updateFocusedWindowLocked
我们继续看WMS#relayoutWindow中的另一个方法updateFocusedWindowLocked,通过RootWindowContainer遍历所有的DisplayContent,执行它们的updateFocusedWindowLocked方法。
//RootWindowContainer.java
boolean updateFocusedWindowLocked(int mode, boolean updateInputWindows) {mTopFocusedAppByProcess.clear();boolean changed = false;int topFocusedDisplayId = INVALID_DISPLAY;// Go through the children in z-order starting at the top-mostfor (int i = mChildren.size() - 1; i >= 0; --i) {final DisplayContent dc = mChildren.get(i);changed |= dc.updateFocusedWindowLocked(mode, updateInputWindows, topFocusedDisplayId);
...
}//DisplayContent.java
boolean updateFocusedWindowLocked(int mode, boolean updateInputWindows,int topFocusedDisplayId) {
...
//计算新焦点窗口是哪个WindowState newFocus = findFocusedWindowIfNeeded(topFocusedDisplayId);if (mCurrentFocus == newFocus) {return false;}
...
//为输入法更新输入窗口adjustForImeIfNeeded();
...
}
所以直接看DisplayContent#updateFocusedWindowLocked,就是计算新焦点窗口,并且为输入法更新之后需要输入的窗口。
补充
1、经过分析我们知道ViewRootImpl会创建SurfaceControl传递给WMS,WMS在创建WindowSurfaceController之后,会调用surfaceController.getSurfaceControl(outSurfaceControl)把上层的outSurfaceControl作为参数传递进去
2、WindowSurfaceController也会自己创建一个SurfaceControl,把它的状态信息拷贝给outSurfaceControl
2、创建WindowSurfaceController的过程中,SurfaceControl会和SurfaceFlinger(SF)进行IPC通信请求一个表面(surface),SF会创建一个Layer对象来表示这个表面
3、创建Layer对象后,会返回一个Handler(句柄)给SurfaceControl,这个句柄包含了新建Layer的相关信息
4、WindowSurfaceController持有这个SurfaceControl来管理窗口表面的属性和生命周期
三、总结
1、ViewRootImpl#setView通过WindwoSession来管理window
2、借助WMS的binder对象调用openSession来获取WindowSession对象,服务端叫Session
3、WMS#addWindow根据客户端window创建了对应的WindowState对象
4、用一个WindowMap集合缓存,key是客户端ViewRootImpl$W的binder对象
5、WindowState和WindowToken双向绑定
6、relayoutWindow对窗口设置了是否可见状态、窗口大小位置、WindowSurfaceController
7、WindowSurfaceController对ViewRootImpl#SurfaceControl状态进行了重新赋值
8、WindowSurfacePlacer对Surface(window)大小位置以及焦点更新
文章讲了这么多,有对Window在WMS层管理进行了创建WindowState,和对window的重新布局,比如刷新大小位置以及焦点的更新。那么View又是怎么处理的呢?我们下一篇文章中继续探索Window的真相。