本文从Android Java层讲解Android Display相关类的初始化。
整体流程如下：
Display Device Discover
1. DisplayAdapter获得DisplayDevice
DisplayManagerService中取得DisplayDevice
LocalDisplayAdapter从BUILT_IN_DISPLAY_IDS_TO_SCAN中获得DISPLAY ID往SurfaceFlinger中查询Display信息(tryConnectDisplayLocked)
private static final int[] BUILT_IN_DISPLAY_IDS_TO_SCAN = new int[] {
SurfaceControl.BUILT_IN_DISPLAY_ID_MAIN,
SurfaceControl.BUILT_IN_DISPLAY_ID_HDMI,
};
private void tryConnectDisplayLocked(int builtInDisplayId) {
//通过display id号去SurfaceFlinger里获得对应的Binder token号
IBinder displayToken = SurfaceControl.getBuiltInDisplay(builtInDisplayId);
if (displayToken != null) {
//通过token号再去SurfaceFlinger获得物理显示器的相关信息
SurfaceControl.PhysicalDisplayInfo[] configs =
SurfaceControl.getDisplayConfigs(displayToken);
int activeConfig = SurfaceControl.getActiveConfig(displayToken);
int activeColorMode = SurfaceControl.getActiveColorMode(displayToken);
int[] colorModes = SurfaceControl.getDisplayColorModes(displayToken);
LocalDisplayDevice device = mDevices.get(builtInDisplayId);
if (device == null) {
// Display was added.
device = new LocalDisplayDevice(displayToken, builtInDisplayId,
configs, activeConfig, colorModes, activeColorMode);
mDevices.put(builtInDisplayId, device);
sendDisplayDeviceEventLocked(device, DISPLAY_DEVICE_EVENT_ADDED);
} else {
...
}
} else {
...
}
}
系统启动时，LocalDisplayAdapter的mDevices并没有保存相关DisplayDevice的信息，所以tryConnectDisplayLocked会直接生成一个新的DisplayDevice,然后加入到LocalDisplayAdapter.mDevices中去, 如 图中标注1 所示, 最后发送一个DISPLAY_DEVICE_EVENT_ADDED信号通过Display已经加入了。
接下来看下LocalDisplayDevice的初始化函数
public LocalDisplayDevice(IBinder displayToken, int builtInDisplayId,
SurfaceControl.PhysicalDisplayInfo[] physicalDisplayInfos, int activeDisplayInfo,
int[] colorModes, int activeColorMode) {
//储存信息
super(LocalDisplayAdapter.this, displayToken, UNIQUE_ID_PREFIX + builtInDisplayId);
//当前LocalDisplayDevice的Display ID号是多少
mBuiltInDisplayId = builtInDisplayId;
updatePhysicalDisplayInfoLocked(physicalDisplayInfos, activeDisplayInfo,
colorModes, activeColorMode);
...
}
LocalDisplayDevice继承于DisplayDevice, 首先通过super函数将一些信息存储在DisplayDevice中，比如与SurfaceFlinger通信的Display Token, uniq ID等
然后又通过updatePhysicalDisplayInfoLocked去更新物理显示屏的信息到具体的类中, 如 图中标注2 所示。
public boolean updatePhysicalDisplayInfoLocked(
SurfaceControl.PhysicalDisplayInfo[] physicalDisplayInfos, int activeDisplayInfo,
int[] colorModes, int activeColorMode) {
//将从SurfaceFlinger获得的物理显示屏的信息全部保存在mDisplayInfos里
mDisplayInfos = Arrays.copyOf(physicalDisplayInfos, physicalDisplayInfos.length);
// mActivePhysIndex 指的是当前 Activity 的配置
mActivePhysIndex = activeDisplayInfo;
ArrayList<DisplayModeRecord> records = new ArrayList<DisplayModeRecord>();
boolean modesAdded = false;
for (int i = 0; i < physicalDisplayInfos.length; i++) {
//通过将物理显示屏的信息放入到 records 中
...
}
// Get the currently active mode
// 获得当前 Activity DisplayModeRecord
DisplayModeRecord activeRecord = null;
for (int i = 0; i < records.size(); i++) {
DisplayModeRecord record = records.get(i);
if (record.hasMatchingMode(physicalDisplayInfos[activeDisplayInfo])){
activeRecord = record;
break;
}
}
// Check whether surface flinger spontaneously changed modes out from under us. Schedule
// traversals to ensure that the correct state is reapplied if necessary.
if (mActiveModeId != 0
&& mActiveModeId != activeRecord.mMode.getModeId()) {
mActiveModeInvalid = true;
sendTraversalRequestLocked();
}
boolean recordsChanged = records.size() != mSupportedModes.size() || modesAdded;
// If the records haven't changed then we're done here.
if (!recordsChanged && !forceUpdate) {
return false;
}
// Update the index of modes.
mHavePendingChanges = true;
mSupportedModes.clear();
// 将records加入到mSupportedModes中
for (DisplayModeRecord record : records) {
mSupportedModes.put(record.mMode.getModeId(), record);
}
...
return true;
}
那这些物理显示屏的信息具体有哪些呢？看下PhysicalDisplayInfo类中的定义便可知
public int width; //显示屏宽度 单位是px
public int height; //显示屏高度 单位是px
public float refreshRate; //显示屏刷新率 59HZ 60HZ ...
public float density; //屏幕密度, 表示每粗寸上有多少个点 120/160/...
public float xDpi;
public float yDpi;
public boolean secure;
public long appVsyncOffsetNanos;
public long presentationDeadlineNanos;
density可以参考Pixel Density
LocalDisplayAdapter将从SF获得的显示屏信息DisplayDevice通知DisplayManagerService Device Added了。
private void handleDisplayDeviceAddedLocked(DisplayDevice device) {
//getDisplayDeviceInfoLocked函数会将物理显示屏的active的信息保存到mInfo也就是DisplayDeviceInfo里
DisplayDeviceInfo info = device.getDisplayDeviceInfoLocked();
if (mDisplayDevices.contains(device)) {
return;
}
// mDebugLastLoggedDeviceInfo 表示的是上一次的DisplayDeviceInfo的信息
device.mDebugLastLoggedDeviceInfo = info;
//将DisplayDevice加入到DMS的mDisplayDevices中去
//如图中标注3所示
mDisplayDevices.add(device);
//为物理显示屏生成一个 LogicalDisplay
LogicalDisplay display = addLogicalDisplayLocked(device);
//updateDisplayStateLocked会触发 DISPLAY_DEVICE_EVENT_CHANGED，
Runnable work = updateDisplayStateLocked(device);
if (work != null) {
work.run();
}
if (display != null && display.getPrimaryDisplayDeviceLocked() == device) {
int colorMode = mPersistentDataStore.getColorMode(device);
if (colorMode == Display.COLOR_MODE_INVALID) {
if ((device.getDisplayDeviceInfoLocked().flags
& DisplayDeviceInfo.FLAG_DEFAULT_DISPLAY) != 0) {
colorMode = mDefaultDisplayDefaultColorMode;
} else {
colorMode = Display.COLOR_MODE_DEFAULT;
}
}
display.setRequestedColorModeLocked(colorMode);
}
scheduleTraversalLocked(false);
}
handleDisplayDeviceAddedLocked函数会为DisplayDevice生成一个对应的LogicalDevice, 同时会将LogicalDevice加入到DisplayManagerService中mLogicalDevices中，同时也将DisplayDevice加入到DisplayManagerService的mDisplayDevices中如 图中标注3 和 图中标注4 所示
为DisplayDevice生成一个LogicalDisplay
private LogicalDisplay addLogicalDisplayLocked(DisplayDevice device) {
DisplayDeviceInfo deviceInfo = device.getDisplayDeviceInfoLocked();
boolean isDefault = (deviceInfo.flags
& DisplayDeviceInfo.FLAG_DEFAULT_DISPLAY) != 0;
// isDefault 表示的是否是默认的Display
if (isDefault && mLogicalDisplays.get(Display.DEFAULT_DISPLAY) != null) {
isDefault = false;
}
//如果不是默认的，而且系统只支持单显示屏模式，那就直接退出了
if (!isDefault && mSingleDisplayDemoMode) {
return null;
}
final int displayId = assignDisplayIdLocked(isDefault);
final int layerStack = assignLayerStackLocked(displayId);
LogicalDisplay display = new LogicalDisplay(displayId, layerStack, device);
//用DisplayDevice中的DisplayDeviceInfo更新LogicalDisplay中的mBaseInfoDisplayInfo
//如 图中标注5 所示
display.updateLocked(mDisplayDevices);
if (!display.isValidLocked()) {
return null;
}
// 如图标注3所示
mLogicalDisplays.put(displayId, display);
// Wake up waitForDefaultDisplay.
// 通知 SystemServer 线程继续执行下面的初始化 具体是在 DisplayManagerService的onBootPhase阶段
// 这样systemserver继续初始化 pkms, wms 等等
if (isDefault) {
mSyncRoot.notifyAll();
}
// 通过 DISPLAY add
sendDisplayEventLocked(displayId, DisplayManagerGlobal.EVENT_DISPLAY_ADDED);
return display;
}
handleDisplayDeviceChanged由updateDisplayStateLocked触发, 它的本意是 DisplayDevice(最底层的显示屏信息已经改变了)那么，就要通知改变它所对应的LogicalDisplay中的相关的信息，
DisplayManagerService
private void handleDisplayDeviceChanged(DisplayDevice device) {
synchronized (mSyncRoot) {
DisplayDeviceInfo info = device.getDisplayDeviceInfoLocked();
if (!mDisplayDevices.contains(device)) {
return;
}
//mDebugLastLoggedDeviceInfo记录的是上一次的DisplayInfo
int diff = device.mDebugLastLoggedDeviceInfo.diff(info);
if (diff == DisplayDeviceInfo.DIFF_STATE) {
Slog.i(TAG, "Display device changed state: \"" + info.name
+ "\", " + Display.stateToString(info.state));
} else if (diff != 0) {
Slog.i(TAG, "Display device changed: " + info);
}
if ((diff & DisplayDeviceInfo.DIFF_COLOR_MODE) != 0) {
try {
mPersistentDataStore.setColorMode(device, info.colorMode);
} finally {
mPersistentDataStore.saveIfNeeded();
}
}
//更新 Last DeviceInfo
device.mDebugLastLoggedDeviceInfo = info;
device.applyPendingDisplayDeviceInfoChangesLocked();
if (updateLogicalDisplaysLocked()) { //更新LogicalDisplay中的相关的信息
scheduleTraversalLocked(false);
}
}
}
2. WMS中关于Display类相关的初始化
WindowManagerService中Display相关类初始化
private WindowManagerService(Context context, InputManagerService inputManager,
boolean haveInputMethods, boolean showBootMsgs, boolean onlyCore,
WindowManagerPolicy policy) {
mRoot = new RootWindowContainer(this);
mDisplayManagerInternal = LocalServices.getService(DisplayManagerInternal.class);
mWindowPlacerLocked = new WindowSurfacePlacer(this);
...
//获得 DisplayManager
mDisplayManager = (DisplayManager)context.getSystemService(Context.DISPLAY_SERVICE);
//通过DisplayManager去获得Displays
mDisplays = mDisplayManager.getDisplays();
for (Display display : mDisplays) {
createDisplayContentLocked(display);
}
}
WMS通过DisplayManager的getDisplays()去获得所有的Display信息，这个可以参考第3小节，
接下来看下 createDisplayContentLocked
private void createDisplayContentLocked(final Display display) {
mRoot.getDisplayContentOrCreate(display.getDisplayId());
}
DisplayContent getDisplayContentOrCreate(int displayId) {
//检查displayId的DisplayContent是否已经创建过了
DisplayContent dc = getDisplayContent(displayId);
if (dc == null) {
final Display display = mService.mDisplayManager.getDisplay(displayId);
if (display != null) {
final long callingIdentity = Binder.clearCallingIdentity();
try {
dc = createDisplayContent(display);
} finally {
Binder.restoreCallingIdentity(callingIdentity);
}
}
}
return dc;
}
private DisplayContent createDisplayContent(final Display display) {
//生成一个新的DisplayContent
final DisplayContent dc = new DisplayContent(display, mService, mLayersController,
mWallpaperController);
final int displayId = display.getDisplayId();
final DisplayInfo displayInfo = dc.getDisplayInfo();
final Rect rect = new Rect();
//获得Overscan的区域, 这个是配置的 /data/system/display_settings.xml
mService.mDisplaySettings.getOverscanLocked(displayInfo.name, displayInfo.uniqueId, rect);
displayInfo.overscanLeft = rect.left;
displayInfo.overscanTop = rect.top;
displayInfo.overscanRight = rect.right;
displayInfo.overscanBottom = rect.bottom;
if (mService.mDisplayManagerInternal != null) {
//这里可能会设置 mOverrideDisplayInfo
mService.mDisplayManagerInternal.setDisplayInfoOverrideFromWindowManager(
displayId, displayInfo);
mService.configureDisplayPolicyLocked(dc);
// TODO(multi-display): Create an input channel for each display with touch capability.
if (displayId == DEFAULT_DISPLAY && mService.canDispatchPointerEvents()) {
dc.mTapDetector = new TaskTapPointerEventListener(
mService, dc);
mService.registerPointerEventListener(dc.mTapDetector);
mService.registerPointerEventListener(mService.mMousePositionTracker);
}
}
return dc;
}
3. DisplayManager中相关初始化
DisplayManager类初始化
public Display[] getDisplays(String category) {
final int[] displayIds = mGlobal.getDisplayIds(); //通过DisplayManagerGlobal去获得DisplayIds
synchronized (mLock) {
try {
if (category == null) { //进入该分支
addAllDisplaysLocked(mTempDisplays, displayIds);
} else if (category.equals(DISPLAY_CATEGORY_PRESENTATION)) {
...
}
return mTempDisplays.toArray(new Display[mTempDisplays.size()]);
} finally {
mTempDisplays.clear();
}
}
}
public int[] getDisplayIds() {
try {
synchronized (mLock) {
if (USE_CACHE) {
if (mDisplayIdCache != null) {
return mDisplayIdCache;
}
}
int[] displayIds = mDm.getDisplayIds(); //通过DisplayManagerService获得当前的显示屏对应的 ID 值
if (USE_CACHE) { //是否使用缓存
mDisplayIdCache = displayIds;
}
//注册DisplayManagerCallback回调函数接收onDisplayEvent事件
//比如 DISPLAY CHANGED/REMOVED/ADDED ... 这时DisplayManager就会更新APP注册过来的回调函数.
registerCallbackIfNeededLocked();
return displayIds;
}
} catch (RemoteException ex) {
throw ex.rethrowFromSystemServer();
}
}
private void addAllDisplaysLocked(ArrayList<Display> displays, int[] displayIds) {
for (int i = 0; i < displayIds.length; i++) {
//getOrCreateDisplayLocked主要是getDisplayInfo接口去请求DMS的DisplayInfo,然后生成Display类
Display display = getOrCreateDisplayLocked(displayIds[i], true /*assumeValid*/);
if (display != null) {
displays.add(display);
}
}
}
可以看出来getDisplayInfoInternal主要是从LogicalDisplay中获得mInfo, 如图中标注6所示.
而mInfo的信息大部分是从mBaseDisplayInfo中获得
private DisplayInfo getDisplayInfoInternal(int displayId, int callingUid) {
synchronized (mSyncRoot) {
LogicalDisplay display = mLogicalDisplays.get(displayId);
if (display != null) {
DisplayInfo info = display.getDisplayInfoLocked();
if (info.hasAccess(callingUid)
|| isUidPresentOnDisplayInternal(callingUid, displayId)) {
return info;
}
}
return null;
}
}
4. ActivityStackSupervior中与Display的关系
ASS与Display的关系
void setWindowManager(WindowManagerService wm) {
synchronized (mService) {
mDisplayManager =
(DisplayManager)mService.mContext.getSystemService(Context.DISPLAY_SERVICE);
//ActivityStackSupervior注册DisplayListener到DisplayManager中去接收Display改变的事件
mDisplayManager.registerDisplayListener(this, null);
mDisplayManagerInternal = LocalServices.getService(DisplayManagerInternal.class);
//获得所有的Display信息
Display[] displays = mDisplayManager.getDisplays();
for (int displayNdx = displays.length - 1; displayNdx >= 0; --displayNdx) {
final int displayId = displays[displayNdx].getDisplayId();
//为display生成对应的 ActivityDisplay信息
ActivityDisplay activityDisplay = new ActivityDisplay(displayId);
mActivityDisplays.put(displayId, activityDisplay);
calculateDefaultMinimalSizeOfResizeableTasks(activityDisplay);
}
...
}
}
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