android 初始化屏幕,Android Display的初始化

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;

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