As stated in the previous Android R DisplayManagerService module (1) startup, the onStart() method starts registering the default Display adapter, and this article analyzes and summarizes the process.
1. Create a screen adapter object
The onStart () method, will be in the android. The display thread that executes registerDefaultDisplayAdapters default DisplayAdapter () method to register:
// frameworks/base/services/core/java/com/android/server/display/DisplayManagerService.java
private void registerDefaultDisplayAdapters(a) {
// Register default display adapters.
synchronized (mSyncRoot) {
// main display adapter
registerDisplayAdapterLocked(newLocalDisplayAdapter( mSyncRoot, mContext, mHandler, mDisplayAdapterListener)); . }}Copy the codeCreated here LocalDisplayAdapter object and the object as a parameter, perform registerDisplayAdapterLocked () method:
// frameworks/base/services/core/java/com/android/server/display/DisplayManagerService.java
private void registerDisplayAdapterLocked(DisplayAdapter adapter) {
mDisplayAdapters.add(adapter);
adapter.registerLocked();
}
Copy the codeFirst, add the LocalDisplayAdapter object to the mDisplayAdapters. MDisplayAdapters is a list of displayAdapters used to store all displayAdapters in THE DMS. There is no extra processing in the LocalDisplayAdapter constructor. The assignment of basic attributes is in its parent DisplayAdapter class:
// frameworks/base/services/core/java/com/android/server/display/DisplayAdapter.java
public DisplayAdapter(DisplayManagerService.SyncRoot syncRoot, Context context, Handler handler, Listener listener, String name) {
// DMS module global synchronization lock
mSyncRoot = syncRoot;
mContext = context;
// Android. display Handler
mHandler = handler;
// Dislayapater.Listener object, used to call back DMS
mListener = listener;
mName = name;
}
Copy the code2. Create physical screen objects
Create good adapter object, will perform registerLocked () method, into the DisplayAdapter, connect and physical screen, LocalDisplayAdapter. RegisterLocked () as follows:
@Override
// frameworks/base/services/core/java/com/android/server/display/LocalDisplayAdapter.java
public void registerLocked(a) {
super.registerLocked();
// Get the physical DisplayId from the SurfaceControl
for (long physicalDisplayId : SurfaceControl.getPhysicalDisplayIds()) {
// Connect Physical DisplaytryConnectDisplayLocked(physicalDisplayId); }}Copy the codeTryConnectDisplayLocked () to create a physical display based on the ID and connect to the DMS:
// frameworks/base/services/core/java/com/android/server/display/LocalDisplayAdapter.java
private void tryConnectDisplayLocked(long physicalDisplayId) {
// Obtain the Display token based on the ID
final IBinder displayToken = SurfaceControl.getPhysicalDisplayToken(physicalDisplayId);
if(displayToken ! =null) {
// Obtain all physical display configuration items based on the token
SurfaceControl.PhysicalDisplayInfo[] configs =
SurfaceControl.getDisplayConfigs(displayToken);
// Obtain the physical display configuration item in use based on the token
intactiveConfig = SurfaceControl.getActiveConfig(displayToken); .// Get the corresponding LocalDisplayDevice from the mDevices array based on the id
LocalDisplayDevice device = mDevices.get(physicalDisplayId);
if (device == null) {
/ / create LocalDisplayDevice
final boolean isInternal = mDevices.size() == 0;
device = new LocalDisplayDevice(displayToken, physicalDisplayId, info,
configs, activeConfig, configSpecs, colorModes, activeColorMode,
hdrCapabilities, isDefaultDisplay);
// Add to mDevices
mDevices.put(physicalDisplayId, device);
// Notify DMS to add the DisplayDevice event
sendDisplayDeviceEventLocked(device, DISPLAY_DEVICE_EVENT_ADDED);
} else if (device.updatePhysicalDisplayInfoLocked(configs, activeConfig,
allowedConfigs, colorModes, activeColorMode)) { / / update the DisplayDevice
// Notify DMS to update the DisplayDevice eventsendDisplayDeviceEventLocked(device, DISPLAY_DEVICE_EVENT_CHANGED); }}else{}}Copy the codeMultiple physical display-related configuration properties are retrieved from the SurfaceControler. The PhysicalDisplayInfo command encapsulates all physical display attribute configurations. You can run the following command to view the configuration information:
adb shell dumpsys display | grep mDisplayInfos
Next, the obtained ID will be used to check whether the corresponding DisplayDevice object exists in the mDevices array. If not, the DisplayDevice object will be created and the DMS will be informed to create the corresponding logical screen after the creation is complete.
LocalDisplayDevice () as follows:
// frameworks/base/services/core/java/com/android/server/display/LocalDisplayAdapter.java
LocalDisplayDevice(IBinder displayToken, long physicalDisplayId,
SurfaceControl.DisplayInfo info, SurfaceControl.DisplayConfig[] configs,
int activeConfigId, SurfaceControl.DesiredDisplayConfigSpecs configSpecs,
int[] colorModes, int activeColorMode, Display.HdrCapabilities hdrCapabilities,
boolean isDefaultDisplay) {
// Set the mDisplayAdapter, mDisplayToken and mUniqueId attributes
super(LocalDisplayAdapter.this, displayToken, UNIQUE_ID_PREFIX + physicalDisplayId);
// Physical screen ID
mPhysicalDisplayId = physicalDisplayId;
// Is the default screen
mIsDefaultDisplay = isDefaultDisplay;
mDisplayInfo = info;
// Update the physical screen configuration
updateDisplayProperties(configs, activeConfigId, configSpecs, colorModes,
activeColorMode, hdrCapabilities);
mSidekickInternal = LocalServices.getService(SidekickInternal.class);
// Get the LightsManager object
if (mIsDefaultDisplay) {
LightsManager lights = LocalServices.getService(LightsManager.class);
mBacklight = lights.getLight(LightsManager.LIGHT_ID_BACKLIGHT);
} else {
mBacklight = null; }...// Create a luminance mapping curve
BackgroundThread.getHandler().sendMessage(PooledLambda.obtainMessage(
LocalDisplayDevice::loadDisplayConfigurationBrightnessMapping, this));
}
Copy the codeHere will be initialized to properties of LocalDisplayDevice, executed after updatePhysicalDisplayInfoLocked () method to update the physical screen configuration, finally get set of backlight mBacklight object, it can be seen that the native mechanism, Even though there are multiple physical screens, there is only one mBacklight.
In the updateDisplayProperties() method, the physical screen configuration, color mode, and HDR mode are updated, respectively.
Create complete LocalDisplayDevice object, after the next execution sendDisplayDeviceEventLocked () method, notice the DMS newly added DisplayDevice events.
3. Notify the DMS that the physical screen is created
The DMS is notified in the DisplayAdapter by way of a callback. The callback interface class is displayAdapter.Listener, which is implemented in the DMS and passed in as a parameter when LocalDisplayAdapter is instantiated.
Next, then see sendDisplayDeviceEventLocked () method:
// frameworks/base/services/core/java/com/android/server/display/DisplayAdapter.java
protected final void sendDisplayDeviceEventLocked(
final DisplayDevice device, final int event) {
// Execute the displayAdapter.listener# onDisplayDeviceEvent() method
mHandler.post(() -> mListener.onDisplayDeviceEvent(device, event));
}
Copy the codeThis mListener object, it is DMS DisplayAdapterListener class objects:
// frameworks/base/services/core/java/com/android/server/display/DisplayManagerService.java
private final class DisplayAdapterListener implements DisplayAdapter.Listener {
@Override
public void onDisplayDeviceEvent(DisplayDevice device, int event) {
switch (event) {
case DisplayAdapter.DISPLAY_DEVICE_EVENT_ADDED:
handleDisplayDeviceAdded(device);
break;
case DisplayAdapter.DISPLAY_DEVICE_EVENT_CHANGED:
handleDisplayDeviceChanged(device);
break;
case DisplayAdapter.DISPLAY_DEVICE_EVENT_REMOVED:
handleDisplayDeviceRemoved(device);
break; }}@Override
public void onTraversalRequested(a) {
synchronized (mSyncRoot) {
scheduleTraversalLocked(false); }}}Copy the codeLocalDisplayAdapter launched after the callback, therefore, to perform handleDisplayDeviceAdded () method, the direct call handleDisplayDeviceAddedLocked () method:
// frameworks/base/services/core/java/com/android/server/display/DisplayManagerService.java
private void handleDisplayDeviceAddedLocked(DisplayDevice device) {
// Get the DisplayDeviceInfo objectDisplayDeviceInfo info = device.getDisplayDeviceInfoLocked(); .// Add to the mDisplayDevices list
mDisplayDevices.add(device);
// Create a logical screen object
LogicalDisplay display = addLogicalDisplayLocked(device);
// Update the display status
Runnable work = updateDisplayStateLocked(device);
if(work ! =null) {
work.run();
}
// Initiate window updates to WMS
scheduleTraversalLocked(false);
}
Copy the codeIn this method, a DisplayDeviceInfo object is first created, then the corresponding logical screen object is created, and finally the status information of Display is updated and a window update request is made to WMS.
5. Create logical screen objects
In the DMS module, use addLogicalDisplayLocked() to create the corresponding logical screen object for the physical screen:
// frameworks/base/services/core/java/com/android/server/display/DisplayManagerService.java
private LogicalDisplay addLogicalDisplayLocked(DisplayDevice device) {
DisplayDeviceInfo deviceInfo = device.getDisplayDeviceInfoLocked();
// Is the default Display
booleanisDefault = (deviceInfo.flags & DisplayDeviceInfo.FLAG_DEFAULT_DISPLAY) ! =0; .// Assign a logical screen ID
final int displayId = assignDisplayIdLocked(isDefault, deviceInfo.address);
// Assign the Layer Stack ID
final int layerStack = assignLayerStackLocked(displayId);
// Create LogicalDisplay object
LogicalDisplay display = new LogicalDisplay(displayId, layerStack, device);
// Update the DisplayDeviceInfo corresponding to physical Display and LogicalDisplaydisplay.updateLocked(mDisplayDevices); . configureColorModeLocked(display, device);// Add to the mLogicalDisplays list
mLogicalDisplays.put(displayId, display);
sendDisplayEventLocked(displayId, DisplayManagerGlobal.EVENT_DISPLAY_ADDED);
return display;
}
Copy the codeIn this method:
- First, before creating a logical display object, an ID and a Layer Stack ID are assigned to the logical screen to be created.
- Then, start creating the LogicalDisplay object;
- Next, execute the LogicalDisplay#updateLocked() method, which updates the DisplayInfo object representing the logical screen information;
- Finally, execute the sendDisplayEventLocked() method to notify components outside the DMS module of adding events to the logical screen.
6. Update the Display status
Back to handleDisplayDeviceAddedLocked (), LogicalDisplay related process execution created for start update DisplayDevice status:
private Runnable updateDisplayStateLocked(DisplayDevice device) {
/ / get DisplayDeviceInfo
DisplayDeviceInfo info = device.getDisplayDeviceInfoLocked();
// Without the FLAG_NEVER_BLANK flag, updates to the DisplayDevice status and brightness are requested
if ((info.flags & DisplayDeviceInfo.FLAG_NEVER_BLANK) == 0) {
return device.requestDisplayStateLocked(mGlobalDisplayState, mGlobalDisplayBrightness);
}
return null;
}
Copy the codeThis method is the key method for updating Display state and brightness in DMS and will be analyzed in the next article.
The sequence diagram of the whole process is as follows:
