我们都知道在android中所有的界面显示相关的,都是通过WindowManager.addView方法来将当前需要显示的View添加到window中。
Window与WindowManager之间的关系
WindowManager的实现类就是WindowManagerImpl:
@Override
public void addView(@NonNull View view, @NonNull ViewGroup.LayoutParams params) {
// 每一个window都又一个唯一标识的token,这里如果没有,则设置系统默认的
applyDefaultToken(params);
// mGlobal是WindowManagerGlobal类型
mGlobal.addView(view, params, mDisplay, mParentWindow);
}
然后通过,ViewRootImpl进一步实现当前需要显示的View的绘制,具体可以参考setContentView那些事
可以看到,在framework中Window和PhoneWindow构成了窗口的抽象部分,其中Window为抽象接口,PhoneWindow为具体实现,同样的WindowManager是实现部分的父类
WindowManagerImpl为具体实现逻辑,在WindowManagerImpl中使用WindowManagerGlobal通过IWindowManager接口与WindowManagerService进行交互,并由WMS完成具体的窗口管理工作
public final class WindowManagerGlobal {
private static IWindowManager sWindowManagerService;
public static IWindowManager getWindowManagerService() {
synchronized (WindowManagerGlobal.class) {
if (sWindowManagerService == null) {
sWindowManagerService = IWindowManager.Stub.asInterface(
ServiceManager.getService("window"));
try {
sWindowManagerService = getWindowManagerService();
ValueAnimator.setDurationScale(sWindowManagerService.getCurrentAnimatorScale());
} catch (RemoteException e) {
Log.e(TAG, "Failed to get WindowManagerService, cannot set animator scale", e);
}
}
return sWindowManagerService;
}
}
}
Window与WindowManager建立连接
在Window中维护了一个mWindowManager属性,可以通过 方法设置一个mWindowManager,来和WindowManager建立连接
public abstract class Window {
private WindowManager mWindowManager;
public void setWindowManager(WindowManager wm, IBinder appToken, String appName) {
setWindowManager(wm, appToken, appName, false);
}
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) {
wm = (WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE);
}
mWindowManager = ((WindowManagerImpl)wm).createLocalWindowManager(this);
}
....
}
关于WindowManagerService
WindowManagerService(WMS),和其他系统服务一样也是在SystemServer中启动的。
public final class SystemServer {
private void startOtherServices() {
....
// 通过WindowManagerService的静态main方法获取一个WindowManagerService实例
wm = WindowManagerService.main(context, inputManager,
mFactoryTestMode != FactoryTest.FACTORY_TEST_LOW_LEVEL,
!mFirstBoot, mOnlyCore);
// 将WMS添加到ServiceManager中
ServiceManager.addService(Context.WINDOW_SERVICE, wm);
ServiceManager.addService(Context.INPUT_SERVICE, inputManager);
mActivityManagerService.setWindowManager(wm);
}
}
在startOtherServices中,获取WindowManagerService实例,然后添加到ServiceManager中,之后我们就可以通过ServiceManager#getService获取WMS了.
WindowManagerService.main方法
通过WindowManagerService.main方法获取WMS实例,其实就是在main方法内部通过异步方法new了一个WindowManagerService实例。
public static WindowManagerService main(final Context context,
final InputManagerService im,
final boolean haveInputMethods, final boolean showBootMsgs,
final boolean onlyCore) {
final WindowManagerService[] holder = new WindowManagerService[1];
DisplayThread.getHandler().runWithScissors(new Runnable() {
@Override
public void run() {
// 通过异步方法创建一个WindowManagerService实例
holder[0] = new WindowManagerService(context, im,
haveInputMethods, showBootMsgs, onlyCore);
}
}, 0);
return holder[0];
}
WindowManagerService构造方法
private WindowManagerService(Context context, InputManagerService inputManager,
boolean haveInputMethods, boolean showBootMsgs, boolean onlyCore) {
// 完成一些初始化工作
mContext = context;
mHaveInputMethods = haveInputMethods;
mAllowBootMessages = showBootMsgs;
mOnlyCore = onlyCore;
// 省略代码
// 获取显示服务
mDisplayManager = (DisplayManager)context.getSystemService(Context.DISPLAY_SERVICE);
// 为每一个display分配一个content
mDisplays = mDisplayManager.getDisplays();
for (Display display : mDisplays) {
createDisplayContentLocked(display);
}
mKeyguardDisableHandler = new KeyguardDisableHandler(mContext, mPolicy);
// 获取PowerManager服务,并且注册LowPowerModeObserver
mPowerManager = (PowerManager)context.getSystemService(Context.POWER_SERVICE);
mPowerManagerInternal = LocalServices.getService(PowerManagerInternal.class);
mPowerManagerInternal.registerLowPowerModeObserver(
new PowerManagerInternal.LowPowerModeListener() {
@Override
public void onLowPowerModeChanged(boolean enabled) {
synchronized (mWindowMap) {
if (mAnimationsDisabled != enabled && !mAllowAnimationsInLowPowerMode) {
mAnimationsDisabled = enabled;
dispatchNewAnimatorScaleLocked(null);
}
}
}
});
// 省略代码
// 获取IActivityManager
mActivityManager = ActivityManagerNative.getDefault();
mBatteryStats = BatteryStatsService.getService();
mAppOps = (AppOpsManager)context.getSystemService(Context.APP_OPS_SERVICE);
AppOpsManager.OnOpChangedInternalListener opListener =
new AppOpsManager.OnOpChangedInternalListener() {
@Override public void onOpChanged(int op, String packageName) {
updateAppOpsState();
}
};
.....
// 构建窗口动画
mAnimator = new WindowAnimator(this);
// 初始化窗口管理策略
initPolicy();
// 开启绘制SurfaceView事务
SurfaceControl.openTransaction();
....
}
深入理解WindowManagerService
WMS主要用来管理当前窗口和对事件的管理和分发,在IWindowManager.aidl文件中定义了大部分WMS的功能方法,另外作为窗口的管理者,WMS里也定义了各种不同的窗口
public class WindowManagerService extends IWindowManager.Stub implements Watchdog.Monitor, WindowManagerPolicy.WindowManagerFuncs {
// 已经启动完成的应用
final ArrayList<AppWindowToken> mFinishedStarting = new ArrayList<>();
// 尺寸正在改变的窗口
final ArrayList<WindowState> mResizingWindows = new ArrayList<>();
// 动画结束的窗口
final ArrayList<WindowState> mPendingRemove = new ArrayList<>();
// 即将释放Surface的窗口
final ArrayList<WindowState> mDestroySurface = new ArrayList<>();
// 失去焦点的窗口
ArrayList<WindowState> mLosingFocus = new ArrayList<>();
// 为了释放内存,需要强制关闭的窗口
final ArrayList<WindowState> mForceRemoves = new ArrayList<>();
// 等待绘制的窗口
ArrayList<WindowState> mWaitingForDrawn = new ArrayList<>();
// 正在打开的应用
final ArraySet<AppWindowToken> mOpeningApps = new ArraySet<>();
// 正在关闭的应用
final ArraySet<AppWindowToken> mClosingApps = new ArraySet<>();
// 当前获得焦点的窗口
WindowState mCurrentFocus = null;
// 上一个获得焦点的窗口
WindowState mLastFocus = null;
// 输入发窗口下方的窗口
WindowState mInputMethodTarget = null;
// 输入法窗口
WindowState mInputMethodWindow = null;
// 得到焦点的应用
AppWindowToken mFocusedApp = null;
}
可以看到在WMS中维护的成员变量大都用到了线性表,不同窗口或者同一个窗口在不同阶段可能位于不同的线性表中,对于窗口,主要分为应用窗口和系统窗口
- 应用窗口
应用窗口中,我们常见的activity所处的窗口,应用对话窗口,应用弹出窗口都属于该类,与应用窗口相关的主要是Window和PhoneWindow类
PhoneWindow继承自Window,应用窗口的添加主要通过WindowManager.addView方法将一个DecorView添加到WindowManager中,具体可以参考setContentView那些事
- 系统窗口
我们平时常见的状态栏,导航栏等都是系统窗口,对于系统窗口,不像activity那样使用setContentView来设置布局,它没有专门的封装类,而是直接使用WindowManager.addView方法
将一个View添加到WindowManager中,下面看下PhoneStatusBar的显示过程。
PhoneStatusBar的显示
对于PhoneStatusBar,其主要的是在addStatusBarWindow中添加当前statusbar到WindowManager中的.
private void addStatusBarWindow() {
// 加载并创建StatusBarWindowView,StatusBarWindowView继承自FrameLayout
makeStatusBarView();
mStatusBarWindowManager = new StatusBarWindowManager(mContext);
// 将StatusBarWindowView添加到WindowManager中
mStatusBarWindowManager.add(mStatusBarWindow, getStatusBarHeight());
}
加载并创建StatusBarWindowView
protected PhoneStatusBarView makeStatusBarView() {
final Context context = mContext;
Resources res = context.getResources();
updateDisplaySize(); // populates mDisplayMetrics
updateResources();
// 加载布局文件,并初始化mStatusBarWindow对象
mStatusBarWindow = (StatusBarWindowView) View.inflate(context,
R.layout.super_status_bar, null);
....
return mStatusBarView;
}
将StatusBarWindowView添加到WindowManager
在StatusBarWindowManager中将StatusBarWindowView添加到WindowManager中的:
public void add(View statusBarView, int barHeight) {
mLp = new WindowManager.LayoutParams(
ViewGroup.LayoutParams.MATCH_PARENT,
barHeight,
WindowManager.LayoutParams.TYPE_STATUS_BAR,
WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
| WindowManager.LayoutParams.FLAG_TOUCHABLE_WHEN_WAKING
| WindowManager.LayoutParams.FLAG_SPLIT_TOUCH
| WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH
| WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS,
PixelFormat.TRANSLUCENT);
mLp.flags |= WindowManager.LayoutParams.FLAG_HARDWARE_ACCELERATED;
mLp.gravity = Gravity.TOP;
mLp.softInputMode = WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE;
mLp.setTitle("StatusBar");
mLp.packageName = mContext.getPackageName();
mStatusBarView = statusBarView;
mBarHeight = barHeight;
mWindowManager.addView(mStatusBarView, mLp);
mLpChanged = new WindowManager.LayoutParams();
mLpChanged.copyFrom(mLp);
}
WindowManager.addView流程分析
上述代码通过WindowManager.addView将当前View显示到屏幕,那么当前View具体是怎么被显示到屏幕的,下面就是我们要讨论的:
我们知道WindowManager是一个接口,其具体的实现类是WindowManagerImpl
public interface WindowManager extends ViewManager
看下WindowManagerImpl#addView方法:
public final class WindowManagerImpl implements WindowManager {
private final WindowManagerGlobal mGlobal = WindowManagerGlobal.getInstance();
@Override
public void addView(@NonNull View view, @NonNull ViewGroup.LayoutParams params) {
android.util.SeempLog.record_vg_layout(383,params);
applyDefaultToken(params);
// mGlobal是WindowManagerGlobal类的实例
mGlobal.addView(view, params, mDisplay, mParentWindow);
}
}
可以看到,上述最终实质上是通过WindowManagerGlobal#addView实现具体的逻辑
public void addView(View view, ViewGroup.LayoutParams params,
Display display, Window parentWindow) {
....
try {
// root是ViewRootImpl的实例
root.setView(view, wparams, panelParentView);
} catch (RuntimeException e) {
....
}
}
继续分析ViewRootImpl#setView的逻辑实现:
public void setView(View view, WindowManager.LayoutParams attrs, View panelParentView) {
synchronized (this) {
if (mView == null) {
mView = view;
....
int res; /* = WindowManagerImpl.ADD_OKAY; */
// 实现具体的绘制操作
requestLayout();
try {
mOrigWindowType = mWindowAttributes.type;
mAttachInfo.mRecomputeGlobalAttributes = true;
collectViewAttributes();
// 通过addToDisplay方法向WMS发起一个Session请求,这里最终会调用Session中对应的方法
res = mWindowSession.addToDisplay(mWindow, mSeq, mWindowAttributes,
getHostVisibility(), mDisplay.getDisplayId(),
mAttachInfo.mContentInsets, mAttachInfo.mStableInsets,
mAttachInfo.mOutsets, mInputChannel);
} catch (RemoteException e) {
....
throw new RuntimeException("Adding window failed", e);
} finally {
if (restore) {
attrs.restore();
}
}
}
}
}
上面的方法主要做了下面的操作:
1. requestLayout(); // 进行具体的绘制操作
2. 调用了Session.addToDisplay方法:
@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);
}
最终还是回到了WMS中与其建立连接,并且上述addToDisplay调用最终返回WMS中的addWindow的返回结果。
final WindowManagerPolicy mPolicy = new PhoneWindowManager();
public int addWindow(Session session, IWindow client, int seq,
WindowManager.LayoutParams attrs, int viewVisibility, int displayId,
Rect outContentInsets, Rect outStableInsets, Rect outOutsets,
InputChannel outInputChannel) {
int[] appOp = new int[1];
// mPolicy实际上是一个PhoneWindowManager类型,在checkAddPermission方法中,首先判断窗口类型是否是系统级别的,
// 如果不是系统级别的窗口,则返回一个ADD_OKAY,否则需要SYSTEM_ALERT_WINDOW或者INTERNAL_SYSTEM_WINDOW权限
int res = mPolicy.checkAddPermission(attrs, appOp);
if (res != WindowManagerGlobal.ADD_OKAY) {
return res;
}
....
synchronized(mWindowMap) {
....
boolean addToken = false;
WindowToken token = mTokenMap.get(attrs.token);
if (token == null) {
// 如果窗口是子窗口
if (type >= FIRST_APPLICATION_WINDOW && type <= LAST_APPLICATION_WINDOW) {
return WindowManagerGlobal.ADD_BAD_APP_TOKEN;
}
// 如果是输入法窗口
if (type == TYPE_INPUT_METHOD) {
return WindowManagerGlobal.ADD_BAD_APP_TOKEN;
}
// 如果是墙纸窗口
if (type == TYPE_WALLPAPER) {
return WindowManagerGlobal.ADD_BAD_APP_TOKEN;
}
// 如果是DayDream窗口,即互动屏保
if (type == TYPE_DREAM) {
return WindowManagerGlobal.ADD_BAD_APP_TOKEN;
}
// 构造WindowToken对象
token = new WindowToken(this, attrs.token, -1, false);
addToken = true;
} else if (type >= FIRST_APPLICATION_WINDOW && type <= LAST_APPLICATION_WINDOW) {
// 获取应用的AppWindowToken
AppWindowToken atoken = token.appWindowToken;
if (atoken == null) {
return WindowManagerGlobal.ADD_NOT_APP_TOKEN;
} else if (atoken.removed) {
return WindowManagerGlobal.ADD_APP_EXITING;
}
if (type == TYPE_APPLICATION_STARTING && atoken.firstWindowDrawn) {
// No need for this guy!
if (localLOGV) Slog.v(
TAG, "**** NO NEED TO START: " + attrs.getTitle());
return WindowManagerGlobal.ADD_STARTING_NOT_NEEDED;
}
} else if (type == TYPE_INPUT_METHOD) {
if (token.windowType != TYPE_INPUT_METHOD) {
// 如果是输入法窗口,token的windowType必须是ADD_BAD_APP_TOKEN类型
return WindowManagerGlobal.ADD_BAD_APP_TOKEN;
}
}
....
// 在窗口的有效性检查完成之后,为当前窗口创建一个WindowState对象,来维护窗口的状态以及根据适当的机制来调整窗口的状态
WindowState win = new WindowState(this, session, client, token,
attachedWindow, appOp[0], seq, attrs, viewVisibility, displayContent);
// 如果客户端已经被销毁
if (win.mDeathRecipient == null) {
return WindowManagerGlobal.ADD_APP_EXITING;
}
if (outInputChannel != null && (attrs.inputFeatures
& WindowManager.LayoutParams.INPUT_FEATURE_NO_INPUT_CHANNEL) == 0) {
// 如果输出Channel的读通道为空,则创建通道
String name = win.makeInputChannelName();
InputChannel[] inputChannels = InputChannel.openInputChannelPair(name);
win.setInputChannel(inputChannels[0]);
inputChannels[1].transferTo(outInputChannel);
// 向InputManager中注册通道,以便当前窗口可以接收到事件
mInputManager.registerInputChannel(win.mInputChannel, win.mInputWindowHandle);
}
.....
}
}
到现在为止,使用WindowManager.addView方法显示对应的View解析就完成了,重点总结一下:
1. WindowManager#addView—>WindowManagerGlobal#addView—>ViewRootImpl#setView
2. 在ViewRootImpl#setView中的requestLayout();实现具体的绘制操作
3. 在ViewRootImpl#setView中调用Session#addToDisplay
4. 在Session#addToDisplay中最终还是回到了WMS中与其建立连接,并且最终调用WMS的addWindow
5. 在WMS的addWindow方法中,主要做了下面几件事:
检查当前窗口的权限,如果不是系统级别的窗口,则返回一个ADD_OKAY,否则需要SYSTEM_ALERT_WINDOW或者INTERNAL_SYSTEM_WINDOW权限
根据当前窗口类型,返回对应的token值
当前窗口创建一个WindowState对象,来维护窗口的状态以及根据适当的机制来调整窗口的状态,并且通过registerInputChannel,以便当前窗口可以接收输入事件