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DisplayManagerService是Android Framework中管理显示屏幕相关的模块#xff0c;各种Display的连接、配置等#xff0c;都是通过DMS和来管理控制。 在DMS模块中#xff0c;对显示屏幕的描述分为物理显示屏(physical display)和逻辑显示屏(logical display)#xff0c…前言
DisplayManagerService是Android Framework中管理显示屏幕相关的模块各种Display的连接、配置等都是通过DMS和来管理控制。 在DMS模块中对显示屏幕的描述分为物理显示屏(physical display)和逻辑显示屏(logical display)物理屏主要从SurfaceFlinger中读取参数创建代表实实在在的物理屏描述其物理特性不同物理屏有不同的属性。逻辑屏则是相对于对物理屏侧重于同一个物理屏的不同逻辑设置受应用和WMS模块影响如显示区域、显示位置坐标、显示方向等。每一个物理屏幕都对应一个逻辑屏幕可以修改逻辑屏幕参数做到同一个物理屏的不同显示方式。 由于不同的物理显示屏有不同的属性和处理方式因此DMS中通过一系列的屏幕适配器(DisplayAdapter)来和分别各种物理显示屏进行连接。
一、DMS模块常见类
1.1 全局管理类
IDisplayManager IBinder接口负责DMS和其他组建的IPC工作DisplayManagerService继承于SystemService的系统服务负责整个系统display的控制和管理DisplayManagerService.LocalService: 继承于DisplayManagerInternal负责system_server内部其他模块和DMS的交互DisplayManagerService.BindService: 继承于IDisplayManager是IDisplayManager的具体实现类DisplayManagerService.CallbackRecord: DMS内部类内部持有IDisplayManagerCallback对象负责执行IDisplayManagerCallback的回调DisplayManager: 暴露给App层的接口内部持有DisplayManagerGlobal对象引用利用DisplayManagerGlobal和DMS进行交互IDisplayManagerCallback一个IBinder接口DMS中发生display相关动作后会通过该接口回调通知给DisplayManagerGlobalDisplayManagerGlobal:内部持有IDisplayManager对象引用App层通过该对象和DMS进行跨IPC交互DisplayManagerGlobal.DisplayManagerCallback: 继承于IDisplayManagerCallback接口负责接收来自DMS中display事件的回调
1.2 数据封装类
DisplayDevice: 屏幕设备对象。DisplayDeviceRepository屏幕设备管理者内部持有DisplayDevice集合负责管理屏幕设备对象。WifiDisplayDeviceDisplayDevice的子类代表通过Wifi连接显示的物理屏幕OverlayDisplayDeviceDisplayDevice的子类开发者选项-模拟辅助显示开启后创建的就是该类对象VirtualDisplayDeviceDisplayDevice的子类表示虚拟显示屏幕用于屏幕录制等LocalDisplayDeviceDisplayDevice的子类代表内置物理屏幕DMS启动后会通过SurfaceControl去读取内置屏幕数据并创建该类对象LogicalDisplay代表逻辑显示屏每一个physical display都会对应一个logical displayLogicalDisplayMapper逻辑屏幕设备管理者内部持有LogicalDisplay对象集合DisplayDeviceInfo DisplayDevice信息封装类在创建DisplayDevice时会进行创建与之对应的是Logical display 的DisplayInfoDisplayInfoLogicalDisplay信息的封装类基本数据由DisplayDeviceInfo中获得app可以通过WMS来修改自己的参数DisplayAdapter 各物理屏和DMS进行连接的适配器LocalDisplayAdapter: 继承于DisplayAdapter 用于LocalDisplayDevice和DMS的连接WifiDisplayAdapter: 继承于DisplayAdapter用于WifiDisplayDevice的和DMS的连接OverlayDisplayAdapter继承于DisplayAdapter用于OverlayDisplayDevice和DMS的连接VirtualDisplayAdapter继承于DisplayAdapter用于VirtualDisplayDevice和DMS的连接DisplayAdapter.Listener用于通知DisplayDevice发生变化的接口DMS中对其进行了实现会接收以下三个事件并根据事件作出全局反应a.添加了新的DisplayDevice ;b.DisplayDevice状态发生变化; c.移除DisplayDevice。DisplayViewport携带有physical display参数用于通知IMS display信息。
1.3 基本类结构的对应关系图 1.4 源码位置
包名目录描述例子android.hardware.displayframeworks/base/core/java/android/hardware/displayDMS模块管理DisplayManager, DisplayMangaerGlobal, …android.viewframeworks/base/core/java/android/view逻辑屏配置项相关DisplayInfo, DisplayViewport, …com.android.server.displayframeworks/base/services/core/java/com/android/server/displayDMS核心DMSDisplayDevice, …
二、DisplayManagerService的启动流程
系统启动后会启动JVM虚拟机SystemServer 是虚拟机的第一个进程由init 进程fork 产生主要用来启动frameworks层中的服务DMS服务也是在这里被启动的下面我们简单列出SystemServer中和DMS启动相关的源码。 frameworks/base/service/java/com/android/server/SystemServer.java public final class SystemServer {private DisplayManagerService mDisplayManagerService;public static void main(String[] args) {new SystemServer().run();}private void run() {...代码省略...try {t.traceBegin(StartServices);startBootstrapServices(t);//引导服务startCoreServices(t);//核心服务startOtherServices(t);//其他服务} catch (Throwable ex) {Slog.e(System, ******************************************);Slog.e(System, ************ Failure starting system services, ex);throw ex;} finally {t.traceEnd(); // StartServices}...代码省略...}private void startBootstrapServices(NonNull TimingsTraceAndSlog t) {...代码省略...// Display manager is needed to provide display metrics before package manager// starts up.t.traceBegin(StartDisplayManager);mDisplayManagerService mSystemServiceManager.startService(DisplayManagerService.class);//通过反射构建对象实例t.traceEnd();// We need the default display before we can initialize the package manager.t.traceBegin(WaitForDisplay);mSystemServiceManager.startBootPhase(t, SystemService.PHASE_WAIT_FOR_DEFAULT_DISPLAY);//调用DMS的onBootPhase方法t.traceEnd();...代码省略...// DisplayManagerService needs to setup android.display scheduling related policies// since setSystemProcess() would have overridden policies due to setProcessGroupmDisplayManagerService.setupSchedulerPolicies();//调用DMS的setupSchedulerPolicies方法...代码省略...}private void startOtherServices(NonNull TimingsTraceAndSlog t) {...代码省略...t.traceBegin(DisplayManagerWindowManagerAndInputReady);mDisplayManagerService.windowManagerAndInputReady();//调用DMS的windowManagerAndInputReady方法t.traceEnd();...代码省略...t.traceBegin(MakeDisplayManagerServiceReady);try {mDisplayManagerService.systemReady(safeMode, mOnlyCore);//调用DMS的systemReady方法} catch (Throwable e) {reportWtf(making Display Manager Service ready, e);}t.traceEnd();}
}2.1 构造方法
DisplayManagerService实例对象是通过SystemServiceManager的startService方法获得的该方法内部先是通过反射构建DisplayManagerService对象实例的然后还会调用该对象的onStart方法先来看下构造方法。 frameworks/base/services/core/java/com/android/server/display/DisplayManagerService.java public final class DisplayManagerService extends SystemService {private final Context mContext;//android.display线程的Handlerprivate final DisplayManagerHandler mHandler;//android.ui线程Handlerprivate final Handler mUiHandler;//主要负责管理和协调设备的显示模式包括分辨率、刷新率等。//它优化了系统的显示设置以平衡性能和电池使用并确保在多显示器配置下的显示效果一致。private final DisplayModeDirector mDisplayModeDirector;//屏幕设备管理者 此类内容维护了一个 DisplayDevice 对象的集合这些对象代表了系统中所有的显示设备。//可以通过这个类跟踪各个显示设备的状态、属性和配置。private final DisplayDeviceRepository mDisplayDeviceRepo;//主要负责逻辑显示设备的映射和管理确保物理显示设备的状态和配置能够正确映射到逻辑显示设备上。//这个类对于支持多显示器和虚拟显示设备的系统功能至关重要。private final LogicalDisplayMapper mLogicalDisplayMapper;private final Injector mInjector;//负责同步和管理屏幕亮度设置以确保多个显示设备或显示区域的亮度一致同时优化用户体验和系统协调。private final BrightnessSynchronizer mBrightnessSynchronizer;public DisplayManagerService(Context context) {this(context, new Injector());}VisibleForTestingDisplayManagerService(Context context, Injector injector) {super(context);mInjector injector;mContext context;//android.display线程handlermHandler new DisplayManagerHandler(DisplayThread.get().getLooper());//android.ui线程HandlermUiHandler UiThread.getHandler();//管理所有的屏幕设备mDisplayDeviceRepo new DisplayDeviceRepository(mSyncRoot, mPersistentDataStore);//负责逻辑显示设备的映射和管理mLogicalDisplayMapper new LogicalDisplayMapper(mContext, mDisplayDeviceRepo,new LogicalDisplayListener(), mSyncRoot, mHandler);//负责管理和协调设备的显示模式mDisplayModeDirector new DisplayModeDirector(context, mHandler);//负责同步和管理屏幕亮度设置mBrightnessSynchronizer new BrightnessSynchronizer(mContext);Resources resources mContext.getResources();mDefaultDisplayDefaultColorMode mContext.getResources().getInteger(com.android.internal.R.integer.config_defaultDisplayDefaultColorMode);mDefaultDisplayTopInset SystemProperties.getInt(PROP_DEFAULT_DISPLAY_TOP_INSET, -1);float[] lux getFloatArray(resources.obtainTypedArray(com.android.internal.R.array.config_minimumBrightnessCurveLux));float[] nits getFloatArray(resources.obtainTypedArray(com.android.internal.R.array.config_minimumBrightnessCurveNits));mMinimumBrightnessCurve new Curve(lux, nits);mMinimumBrightnessSpline Spline.createSpline(lux, nits);mCurrentUserId UserHandle.USER_SYSTEM;ColorSpace[] colorSpaces SurfaceControl.getCompositionColorSpaces();mWideColorSpace colorSpaces[1];mAllowNonNativeRefreshRateOverride mInjector.getAllowNonNativeRefreshRateOverride();mSystemReady false;}
}2.2 执行onStart方法
public final class DisplayManagerService extends SystemService {private final PersistentDataStore mPersistentDataStore new PersistentDataStore();Overridepublic void onStart() {// 加载数据synchronized (mSyncRoot) {mPersistentDataStore.loadIfNeeded();//加载display中的固定数据loadStableDisplayValuesLocked();}// 在android.display线程中创建默认DisplayAdapter并进行注册mHandler.sendEmptyMessage(MSG_REGISTER_DEFAULT_DISPLAY_ADAPTERS);// If there was a runtime restart then we may have stale caches left around, so we need to// make sure to invalidate them upon every start.DisplayManagerGlobal.invalidateLocalDisplayInfoCaches();//向ServiceManager注册BinderService以便其他模块可以跨进程调用publishBinderService(Context.DISPLAY_SERVICE, new BinderService(),true /*allowIsolated*/);//注册Local ServicepublishLocalService(DisplayManagerInternal.class, new LocalService());}}2.2.1 加载display中的固定数据 frameworks/base/services/core/java/com/android/server/display/PersistentDataStore.java final class PersistentDataStore {private Injector mInjector;public PersistentDataStore() {this(new Injector());}VisibleForTestingPersistentDataStore(Injector injector) {mInjector injector;}public void loadIfNeeded() {if (!mLoaded) {load();mLoaded true;}}private void load() {clearState();final InputStream is;try {is mInjector.openRead();} catch (FileNotFoundException ex) {return;}TypedXmlPullParser parser;try {parser Xml.resolvePullParser(is);loadFromXml(parser);} catch (IOException ex) {Slog.w(TAG, Failed to load display manager persistent store data., ex);clearState();} catch (XmlPullParserException ex) {Slog.w(TAG, Failed to load display manager persistent store data., ex);clearState();} finally {IoUtils.closeQuietly(is);}}static class Injector {private final AtomicFile mAtomicFile;public Injector() {//display配置的文件路径mAtomicFile new AtomicFile(new File(/data/system/display-manager-state.xml), display-state);}public InputStream openRead() throws FileNotFoundException {return mAtomicFile.openRead();}public OutputStream startWrite() throws IOException {return mAtomicFile.startWrite();}public void finishWrite(OutputStream os, boolean success) {if (!(os instanceof FileOutputStream)) {throw new IllegalArgumentException(Unexpected OutputStream as argument: os);}FileOutputStream fos (FileOutputStream) os;if (success) {mAtomicFile.finishWrite(fos);} else {mAtomicFile.failWrite(fos);}}}
}利用PersistentDataStore加载display中的固定数据这些数据都是以xml文件的形式保存在/data/system/display-manager-state.xml中
2.2.2 注册屏幕适配器
public final class DisplayManagerService extends SystemService {private static final int MSG_REGISTER_DEFAULT_DISPLAY_ADAPTERS 1;private static final int MSG_REGISTER_ADDITIONAL_DISPLAY_ADAPTERS 2;Overridepublic void onStart() {...代码省略...// android.display线程中创建默认DisplayAdapter并进行注册mHandler.sendEmptyMessage(MSG_REGISTER_DEFAULT_DISPLAY_ADAPTERS);...代码省略...}private final class DisplayManagerHandler extends Handler {Overridepublic void handleMessage(Message msg) {switch (msg.what) {case MSG_REGISTER_DEFAULT_DISPLAY_ADAPTERS://注册默认的屏幕适配器registerDefaultDisplayAdapters();break;case MSG_REGISTER_ADDITIONAL_DISPLAY_ADAPTERS://注册额外的屏幕设备适配器registerAdditionalDisplayAdapters();break;...代码省略... }}}private void registerDefaultDisplayAdapters() {synchronized (mSyncRoot) {//注册默认的屏幕适配器registerDisplayAdapterLocked(new LocalDisplayAdapter(mSyncRoot, mContext, mHandler, mDisplayDeviceRepo));//注册虚拟的屏幕适配器mVirtualDisplayAdapter mInjector.getVirtualDisplayAdapter(mSyncRoot, mContext,mHandler, mDisplayDeviceRepo);if (mVirtualDisplayAdapter ! null) {registerDisplayAdapterLocked(mVirtualDisplayAdapter);}}}
}2.3 执行onBootPhase方法
DisplayManagerService的onStart()方法被执行完毕后onBootPhase()方法将会被执行。
public final class DisplayManagerService extends SystemService {Overridepublic void onBootPhase(int phase) {if (phase PHASE_WAIT_FOR_DEFAULT_DISPLAY) {synchronized (mSyncRoot) {//Injector的getDefaultDisplayDelayTimeout默认返回10秒long timeout SystemClock.uptimeMillis() mInjector.getDefaultDisplayDelayTimeout();// 超过timeout之后如果默认屏幕的逻辑显示屏为空则抛出异常while (mLogicalDisplayMapper.getDisplayLocked(Display.DEFAULT_DISPLAY) null|| mVirtualDisplayAdapter null) {long delay timeout - SystemClock.uptimeMillis();if (delay 0) {throw new RuntimeException(Timeout waiting for default display to be initialized. DefaultDisplay mLogicalDisplayMapper.getDisplayLocked(Display.DEFAULT_DISPLAY) , mVirtualDisplayAdapter mVirtualDisplayAdapter);}if (DEBUG) {Slog.d(TAG, waitForDefaultDisplay: waiting, timeout delay);}try {mSyncRoot.wait(delay);} catch (InterruptedException ex) {}}}} else if (phase PHASE_BOOT_COMPLETED) {mDisplayModeDirector.onBootCompleted();}}
}PHASE_WAIT_FOR_DEFAULT_DISPLAY阶段是最早的一个启动阶段当一些引导服务启动完毕后启动后续服务时检查DMS是否已经创建默认逻辑屏如果在10s内没有完成默认LogicalDisplay的创建则抛出异常。
2.4 执行setupSchedulerPolicies方法
public final class DisplayManagerService extends SystemService {public void setupSchedulerPolicies() {// 给android.display、android.anim、android.anim.lf三个线程设置组和CPU集Process.setThreadGroupAndCpuset(DisplayThread.get().getThreadId(),Process.THREAD_GROUP_TOP_APP);Process.setThreadGroupAndCpuset(AnimationThread.get().getThreadId(),Process.THREAD_GROUP_TOP_APP);Process.setThreadGroupAndCpuset(SurfaceAnimationThread.get().getThreadId(),Process.THREAD_GROUP_TOP_APP);}}给以上三个线程设置线程组和调度集将线程组设为Process.THREAD_GROUP_TOP_APP以确保更加高效的执行。
2.5 执行windowManagerAndInputReady方法
当SystemServer中启动WindowManagerService和InputManagerService后将调用此方法通知DMS。
public final class DisplayManagerService extends SystemService {private static final int MSG_REQUEST_TRAVERSAL 4;//WMS和输入法启动完毕public void windowManagerAndInputReady() {synchronized (mSyncRoot) {mWindowManagerInternal LocalServices.getService(WindowManagerInternal.class);mInputManagerInternal LocalServices.getService(InputManagerInternal.class);//获取设备状态服务并设置回调对象DeviceStateManager deviceStateManager mContext.getSystemService(DeviceStateManager.class);deviceStateManager.registerCallback(new HandlerExecutor(mHandler), new DeviceStateListener());//通知WMS进行窗口更新流程scheduleTraversalLocked(false);}}private void scheduleTraversalLocked(boolean inTraversal) {if (!mPendingTraversal mWindowManagerInternal ! null) {mPendingTraversal true;if (!inTraversal) {mHandler.sendEmptyMessage(MSG_REQUEST_TRAVERSAL);}}}private final class DisplayManagerHandler extends Handler {Overridepublic void handleMessage(Message msg) {switch (msg.what) {...代码省略... case MSG_REQUEST_TRAVERSAL://通知WMS进行窗口更新流程mWindowManagerInternal.requestTraversalFromDisplayManager();break;...代码省略... }}}} 先是获得WMS和IMS各自的LocalService对象然后将发起显示内容更新流程请求WMS模块进行窗口更新。DMS和WMS联系非常紧密通常当DMS中相关属性发生变化后会通知WMS进行窗口更新WMS在更新过程中也会通知DMS应用来自窗口的Display相关属性。
2.6 执行systemReady方法
此方法DMS在SystemServer中被调用的最后一个方法通知DMS启动完成
public final class DisplayManagerService extends SystemService {private static final String PROP_DEFAULT_DISPLAY_TOP_INSET persist.sys.displayinset.top;private static final int MSG_REGISTER_DEFAULT_DISPLAY_ADAPTERS 1;//注册物理屏幕适配器、虚拟屏幕适配器private static final int MSG_REGISTER_ADDITIONAL_DISPLAY_ADAPTERS 2;//注册其他屏幕适配器public void systemReady(boolean safeMode, boolean onlyCore) {synchronized (mSyncRoot) {mSafeMode safeMode;mOnlyCore onlyCore;mSystemReady true;//启动完成//将默认Display的top inset存储到persist.sys.displayinset.top中recordTopInsetLocked(mLogicalDisplayMapper.getDisplayLocked(Display.DEFAULT_DISPLAY));updateSettingsLocked();updateUserDisabledHdrTypesFromSettingsLocked();}mDisplayModeDirector.setDesiredDisplayModeSpecsListener(new DesiredDisplayModeSpecsObserver());mDisplayModeDirector.start(mSensorManager);//注册除了物理屏幕适配器、虚拟屏幕适配器以外的其他屏幕适配器mHandler.sendEmptyMessage(MSG_REGISTER_ADDITIONAL_DISPLAY_ADAPTERS);mSettingsObserver new SettingsObserver();mBrightnessSynchronizer.startSynchronizing();}private void recordTopInsetLocked(Nullable LogicalDisplay d) {if (!mSystemReady || d null) {return;}int topInset d.getInsets().top;if (topInset mDefaultDisplayTopInset) {return;}mDefaultDisplayTopInset topInset;//将默认Display的top inset存储到persist.sys.displayinset.top中SystemProperties.set(PROP_DEFAULT_DISPLAY_TOP_INSET, Integer.toString(topInset));} private final class DisplayManagerHandler extends Handler {Overridepublic void handleMessage(Message msg) {switch (msg.what) {case MSG_REGISTER_DEFAULT_DISPLAY_ADAPTERS://注册默认的屏幕适配器registerDefaultDisplayAdapters();break;case MSG_REGISTER_ADDITIONAL_DISPLAY_ADAPTERS://注册额外的屏幕设备适配器registerAdditionalDisplayAdapters();break;...代码省略... }}}//注册额外的屏幕适配器对象private void registerAdditionalDisplayAdapters() {synchronized (mSyncRoot) {if (shouldRegisterNonEssentialDisplayAdaptersLocked()) {registerOverlayDisplayAdapterLocked();//注册模拟辅助设备屏幕适配器registerWifiDisplayAdapterLocked();//注册WIFI屏幕适配器}}}private void registerOverlayDisplayAdapterLocked() {registerDisplayAdapterLocked(new OverlayDisplayAdapter(mSyncRoot, mContext, mHandler, mDisplayDeviceRepo, mUiHandler));}private void registerWifiDisplayAdapterLocked() {if (mContext.getResources().getBoolean(com.android.internal.R.bool.config_enableWifiDisplay)|| SystemProperties.getInt(FORCE_WIFI_DISPLAY_ENABLE, -1) 1) {mWifiDisplayAdapter new WifiDisplayAdapter(mSyncRoot, mContext, mHandler, mDisplayDeviceRepo,mPersistentDataStore);registerDisplayAdapterLocked(mWifiDisplayAdapter);}}private void registerDisplayAdapterLocked(DisplayAdapter adapter) {//将适配器对面添加到适配器集合中mDisplayAdapters.add(adapter);adapter.registerLocked();}
} 此方法该会通过mHandler发起注册其他DeviceAdapter的操作最终完成四种DisplayAdapter的注册。
三 总结
