Android framework配置默认屏幕亮度值源码分析

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        222115        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。

觉得本文对您有用，麻烦点赞、关注、收藏，您的肯定是我创作的无限动力，谢谢！！！