Android 系统设置中显示设置之亮度调节篇
在上一篇博客中，我们学习了显示设置中休眠设置和屏保设置的基本内容。在这一篇中我们来学习设备亮度的调节，首先还是学习在DisplaySettings.xml增加了一个叫做BrightnessPreference的preference的选项用来控制亮度调节。
步骤1：当用户点击BrightnessPreference的时候，由BrightnessPreference做对应的处理（注：其实是发送了一个广播）
1 public class BrightnessPreference extends Preference { 2 3 public BrightnessPreference(Context context, AttributeSet attrs) { 4 super(context, attrs); 5 } 6 7 @Override 8 protected void onClick() { 9 //发送了一个显示亮度调节对话框的广播10 Intent intent = new Intent(Intent.ACTION_SHOW_BRIGHTNESS_DIALOG);11 getContext().sendBroadcastAsUser(intent, UserHandle.CURRENT_OR_SELF);12 }13 }
步骤2：对广播的注册并处理，有一个SettingsUI的类继承自SystemUI，该类负责监听上面的广播并进行处理，详见：
1 public class SettingsUI extends SystemUI { 2 private static final String TAG = "SettingsUI"; 3 private static final boolean DEBUG = false; 4 private final Handler mHandler = new Handler(); 5 private BrightnessDialog mBrightnessDialog; 6 private BroadcastReceiver mIntentReceiver = new BroadcastReceiver() { 7 @Override 8 public void onReceive(Context context, Intent intent) { 9 String action = intent.getAction();10 if (action.equals(Intent.ACTION_SHOW_BRIGHTNESS_DIALOG)) {11 if (DEBUG) Log.d(TAG, "showing brightness dialog");12 if (mBrightnessDialog == null) {13 mBrightnessDialog = new BrightnessDialog(mContext);14 mBrightnessDialog.setOnDismissListener(new DialogInterface.OnDismissListener() {15 @Override16 public void onDismiss(DialogInterface dialog) {17 mBrightnessDialog = null;}});18 }19 if (!mBrightnessDialog.isShowing()) {20 //显示亮度调节的dialog21 mBrightnessDialog.show(); }22 } else {23 Log.w(TAG, "unknown intent: " + intent);}}};24 25 public void start() {26 //监听ACTION_SHOW_BRIGHTNESS_DIALOG广播27 IntentFilter filter = new IntentFilter();28 filter.addAction(Intent.ACTION_SHOW_BRIGHTNESS_DIALOG);29 mContext.registerReceiverAsUser(mIntentReceiver, UserHandle.ALL, filter, null, mHandler);30 }
步骤3：上面是负责显示亮度调节的对话框，具体的设置需要查看BrightnessDialog，详见：
1 /** 2 * Create the brightness dialog and any resources that are used for the 3 * entire lifetime of the dialog. 4 */ 5 @Override 6 public void onCreate(Bundle savedInstanceState) { 7 super.onCreate(savedInstanceState); 8 9 Window window = getWindow();10 window.setType(WindowManager.LayoutParams.TYPE_VOLUME_OVERLAY);11 window.getAttributes().privateFlags |=12 WindowManager.LayoutParams.PRIVATE_FLAG_SHOW_FOR_ALL_USERS;13 window.clearFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);14 window.requestFeature(Window.FEATURE_NO_TITLE);15 //dialog显示的内容quick_settings_brightness_dialog.xml16 setContentView(R.layout.quick_settings_brightness_dialog);17 setCanceledOnTouchOutside(true);18 }19 20 21 @Override22 protected void onStart() {23 super.onStart();24 //对亮度的调节主要是使用了BrightnessController类25 mBrightnessController = new BrightnessController(getContext(),26 (ImageView) findViewById(R.id.brightness_icon),27 (ToggleSlider) findViewById(R.id.brightness_slider));28 dismissBrightnessDialog(mBrightnessDialogLongTimeout);29 mBrightnessController.addStateChangedCallback(this);30 }
步骤4： BrightnessController详解：
我们这里主要还是学习下一些基本的内容，具体包括获取设备最大的亮度和最低的亮度值、如果设置屏幕的亮度、当前的亮度值和亮度调节模式保存和获取的位置。
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- 获取设备的最大和最低亮度值
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1 //获取PowerManager对象2 PowerManager pm = (PowerManager)context.getSystemService(Context.POWER_SERVICE);3 //鑾峰彇璁惧鐨勬渶澶т寒搴?4 mMinimumBacklight = pm.getMinimumScreenBrightnessSetting();5 //鑾峰彇璁惧鐨勬渶浣庝寒搴?6 mMaximumBacklight = pm.getMaximumScreenBrightnessSetting();
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- 设置屏幕亮度
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//首先获取IPowerManager对象 mPower = IPowerManager.Stub.asInterface(ServiceManager.getService("power")); private void setBrightness(int brightness) { try { mPower.setTemporaryScreenBrightnessSettingOverride(brightness); } catch (RemoteException ex) { } }
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- 亮度值和亮度模式的读取和存储
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1 //设置亮度的设置模式，mode=0表示为手动，mode=1表示自动调节2 private void setMode(int mode) {3 //存储位置为Settings.system中4 Settings.System.putIntForUser(mContext.getContentResolver(),5 Settings.System.SCREEN_BRIGHTNESS_MODE, mode,6 mUserTracker.getCurrentUserId());7 } //以下的代码是负责取出设置模式的 int automatic;
try { automatic = Settings.System.getIntForUser(mContext.getContentResolver(), Settings.System.SCREEN_BRIGHTNESS_MODE, UserHandle.USER_CURRENT); } catch (SettingNotFoundException snfe) { automatic = 0; }
//以下的代码是将亮度值保存到Settings.system中 if (!tracking) { AsyncTask.execute(new Runnable() { public void run() { Settings.System.putIntForUser(mContext.getContentResolver(), Settings.System.SCREEN_BRIGHTNESS, val, UserHandle.USER_CURRENT); } }); }
/** Fetch the brightness from the system settings and update the slider */ private void updateSlider() { int value; try { //从Settings.System中获取亮度值 value = Settings.System.getIntForUser(mContext.getContentResolver(), Settings.System.SCREEN_BRIGHTNESS, UserHandle.USER_CURRENT); } catch (SettingNotFoundException ex) { value = mMaximumBacklight; } mControl.setMax(mMaximumBacklight - mMinimumBacklight); mControl.setValue(value - mMinimumBacklight); }
杂谈：
我们在BrightnessController中找到了一个内部类叫做BrightnessController，它继承自ContentObserver。该过程使用了观察者设计模式，主要是用来负责对ContentProvider中指定的URI进行监听，如果该URI对应的数据发生了变化就可以及时得到监听并处理。它的使用请参考：。
BrightnessController主要是监听了
private final Uri BRIGHTNESS_MODE_URI = Settings.System.getUriFor(Settings.System.SCREEN_BRIGHTNESS_MODE);//亮度调节模式 private final Uri BRIGHTNESS_URI = Settings.System.getUriFor(Settings.System.SCREEN_BRIGHTNESS);//亮度值
1 //当监听的uri发生变化时，回调onChange函数 2 @Override 3 public void onChange(boolean selfChange, Uri uri) { 4 if (selfChange) return; 5 if (BRIGHTNESS_MODE_URI.equals(uri)) { 6 updateMode();//更新模式 7 } else if (BRIGHTNESS_URI.equals(uri)) { 8 updateSlider();//更新拖动条 9 } else {10 updateMode();11 updateSlider();12 }13 for (BrightnessStateChangeCallback cb : mChangeCallbacks) {14 cb.onBrightnessLevelChanged();15 }16 }
以上就是对亮度调节的基本内容，希望大家能够喜欢，您的支持是我不懈的动力，当然不喜勿喷，有错请指正！