1、概述
在Android中，config.xml文件用于配置各种系统设置和资源。对于屏幕亮度的配置，config.xml并不是直接用于设置屏幕亮度的地方，但它可以包含默认的系统设置和一些相关的参数。以下是如何在config.xml中配置一些与屏幕亮度相关的设置的详细步骤。
2、找到或创建config.xml
在Android系统源码中，config.xml通常位于以下路径：
frameworks/base/core/res/res/values/config.xml
如果项目中没有config.xml文件，可以在相应的路径下创建一个。
3、配置屏幕亮度相关参数
在config.xml中，可以定义与屏幕亮度相关的参数，例如默认亮度值、自动亮度调节参数等。以下是一个示例配置：
true true true true - "wifi,1,1,1,-1,true"
- "mobile,0,0,0,-1,true"
- "mobile_mms,2,0,2,60000,true"
- "mobile_supl,3,0,2,60000,true"
- "mobile_hipri,5,0,3,60000,true"
- "mobile_fota,10,0,2,60000,true"
- "mobile_ims,11,0,2,60000,true"
- "mobile_cbs,12,0,2,60000,true"
- "wifi_p2p,13,1,0,-1,true"
- "eth,9,9,4,60000,true"
- "1,1"
- "0,1"
- "9,1"
10 222 115 1 false true - com.google.android.location
- com.android.location.fused
1 true 5000 200
4、部分参数解读
config_screenBrightnessSettingDefault：设置屏幕亮度的默认值。这个值会在系统初始化时使用，范围是0到255。
config_screenBrightnessSettingMinimum：设置屏幕亮度的最低值。这个值确保屏幕亮度不会低于这个值，范围是0到255。
config_screenBrightnessSettingMaximum：设置屏幕亮度的最高值。这个值确保屏幕亮度不会高于这个值，范围是0到255。
5、使用配置
这些配置会被系统服务（如PowerManagerService、DisplayManagerService）读取并应用，具体实现可以参考前面提到的服务类。
例如，在PowerManagerService中，可以读取配置并应用默认亮度值：
public void systemReady(TwilightService twilight, DreamManagerService dreamManager) {
synchronized (mLock) {
mSystemReady = true;
mDreamManager = dreamManager;
PowerManager pm = (PowerManager)mContext.getSystemService(Context.POWER_SERVICE);
mScreenBrightnessSettingMinimum = pm.getMinimumScreenBrightnessSetting();
mScreenBrightnessSettingMaximum = pm.getMaximumScreenBrightnessSetting();
mScreenBrightnessSettingDefault = pm.getDefaultScreenBrightnessSetting();
SensorManager sensorManager = new SystemSensorManager(mHandler.getLooper());
// The notifier runs on the system server's main looper so as not to interfere
// with the animations and other critical functions of the power manager.
mNotifier = new Notifier(Looper.getMainLooper(), mContext, mBatteryStats,
createSuspendBlockerLocked("PowerManagerService.Broadcasts"),
mScreenOnBlocker, mPolicy);
// The display power controller runs on the power manager service's
// own handler thread to ensure timely operation.
mDisplayPowerController = new DisplayPowerController(mHandler.getLooper(),
mContext, mNotifier, mLightsService, twilight, sensorManager,
mDisplayManagerService, mDisplayBlanker,
mDisplayPowerControllerCallbacks, mHandler);
mWirelessChargerDetector = new WirelessChargerDetector(sensorManager,
createSuspendBlockerLocked("PowerManagerService.WirelessChargerDetector"));
mSettingsObserver = new SettingsObserver(mHandler);
mAttentionLight = mLightsService.getLight(LightsService.LIGHT_ID_ATTENTION);
// Register for broadcasts from other components of the system.
IntentFilter filter = new IntentFilter();
filter.addAction(Intent.ACTION_BATTERY_CHANGED);
mContext.registerReceiver(new BatteryReceiver(), filter, null, mHandler);
filter = new IntentFilter();
filter.addAction(Intent.ACTION_BOOT_COMPLETED);
mContext.registerReceiver(new BootCompletedReceiver(), filter, null, mHandler);
filter = new IntentFilter();
filter.addAction(Intent.ACTION_DREAMING_STARTED);
filter.addAction(Intent.ACTION_DREAMING_STOPPED);
mContext.registerReceiver(new DreamReceiver(), filter, null, mHandler);
filter = new IntentFilter();
filter.addAction(Intent.ACTION_USER_SWITCHED);
mContext.registerReceiver(new UserSwitchedReceiver(), filter, null, mHandler);
filter = new IntentFilter();
filter.addAction(Intent.ACTION_DOCK_EVENT);
mContext.registerReceiver(new DockReceiver(), filter, null, mHandler);
// Register for settings changes.
final ContentResolver resolver = mContext.getContentResolver();
resolver.registerContentObserver(Settings.Secure.getUriFor(
Settings.Secure.SCREENSAVER_ENABLED),
false, mSettingsObserver, UserHandle.USER_ALL);
resolver.registerContentObserver(Settings.Secure.getUriFor(
Settings.Secure.SCREENSAVER_ACTIVATE_ON_SLEEP),
false, mSettingsObserver, UserHandle.USER_ALL);
resolver.registerContentObserver(Settings.Secure.getUriFor(
Settings.Secure.SCREENSAVER_ACTIVATE_ON_DOCK),
false, mSettingsObserver, UserHandle.USER_ALL);
resolver.registerContentObserver(Settings.System.getUriFor(
Settings.System.SCREEN_OFF_TIMEOUT),
false, mSettingsObserver, UserHandle.USER_ALL);
resolver.registerContentObserver(Settings.Global.getUriFor(
Settings.Global.STAY_ON_WHILE_PLUGGED_IN),
false, mSettingsObserver, UserHandle.USER_ALL);
resolver.registerContentObserver(Settings.System.getUriFor(
Settings.System.SCREEN_BRIGHTNESS),
false, mSettingsObserver, UserHandle.USER_ALL);
resolver.registerContentObserver(Settings.System.getUriFor(
Settings.System.SCREEN_BRIGHTNESS_MODE),
false, mSettingsObserver, UserHandle.USER_ALL);
//--------------for hdmi timeout add by dzy
resolver.registerContentObserver(Settings.System.getUriFor(
Settings.System.HDMI_LCD_TIMEOUT),
false, mSettingsObserver, UserHandle.USER_ALL);
//-----------------end------------------
// Go.
readConfigurationLocked();
updateSettingsLocked();
mDirty |= DIRTY_BATTERY_STATE;
updatePowerStateLocked();
new Thread() {
public void run() {
boolean waitSuspendOK;
while(true) {
waitSuspendOK = false;
try {
Slog.d(TAG, "--- nativeWaitSuspendTimeout");
nativeWaitSuspendTimeout();
waitSuspendOK = true;
} catch (IOException e) {
Slog.e(TAG, "--- nativeWaitSuspendTimeout: " + e);
}
if (waitSuspendOK) {
int status = -1;
try {
status = nativeGetChargingStatus();
Slog.d(TAG, "--- charging status=" + status);
} catch (IOException e) {
Slog.e(TAG, "--- nativeGetChargingStatus: " + e);
}
if (status != 1) {
PowerManager pm = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE);
PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "suspend timeout to shutdownNormal");
wl.acquire(5000);
Slog.d(TAG, "--- shutdown now");
shutdownNormal();
}
} else {
try {
Thread.sleep(500);
} catch (InterruptedException e) {
}
}
}
}
}.start();
}
}
6、总结
通过在config.xml中配置屏幕亮度相关的参数，可以为Android系统提供默认的亮度设置和自动亮度调节的参数。这些配置会在系统服务中被读取并应用，从而影响系统的亮度控制行为。通过这种方式，开发者可以灵活地配置和管理屏幕亮度，确保提供良好的用户体验。
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