系统环境：
Platform: RK3399
OS: Android 7.1
Kernel: v4.4.83
使用场景
最近在研究AndroidL Settings的代码，写了一个简单的控件来操控屏幕亮度。
其实，调节屏幕亮度的场景应用很广，例如很多视频应用都响应touch事件来进行亮度调节。
[屏幕亮度调节模式]
首先，需要明确屏幕亮度有两种调节模式：
Settings.System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC：值为1，自动调节亮度。
Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL：值为0，手动模式。
如果需要实现亮度调节，首先需要设置屏幕亮度调节模式为手动模式。
BrightnessDialog及其控制
# BrightnessDialog
frameworks\base\packages\SystemUI\src\com\android\systemui\settings\BrightnessDialog.java
public class BrightnessDialog extends Activity {
private BrightnessController mBrightnessController;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
final Window window = getWindow();
window.setGravity(Gravity.TOP);
window.clearFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);
window.requestFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.quick_settings_brightness_dialog);
final ImageView icon = (ImageView) findViewById(R.id.brightness_icon);
final ToggleSlider slider = (ToggleSlider) findViewById(R.id.brightness_slider);
mBrightnessController = new BrightnessController(this, icon, slider);
}
@Override
protected void onStart() {
super.onStart();
mBrightnessController.registerCallbacks();
MetricsLogger.visible(this, MetricsEvent.BRIGHTNESS_DIALOG);
}
@Override
protected void onStop() {
super.onStop();
MetricsLogger.hidden(this, MetricsEvent.BRIGHTNESS_DIALOG);
mBrightnessController.unregisterCallbacks();
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_VOLUME_DOWN
|| keyCode == KeyEvent.KEYCODE_VOLUME_UP
|| keyCode == KeyEvent.KEYCODE_VOLUME_MUTE) {
finish();
}
return super.onKeyDown(keyCode, event);
}
}
BrightnessDialog控制
# BrightnessDialog控制
frameworks\base\packages\SystemUI\src\com\android\systemui\settings\BrightnessController.java
public class BrightnessController implements ToggleSlider.Listener {
private static final String TAG = "StatusBar.BrightnessController";
private static final boolean SHOW_AUTOMATIC_ICON = false;
/**
* {@link android.provider.Settings.System#SCREEN_AUTO_BRIGHTNESS_ADJ} uses the range [-1, 1].
* Using this factor, it is converted to [0, BRIGHTNESS_ADJ_RESOLUTION] for the SeekBar.
*/
private static final float BRIGHTNESS_ADJ_RESOLUTION = 2048;
private static final int MSG_UPDATE_ICON = 0;
private static final int MSG_UPDATE_SLIDER = 1;
private static final int MSG_SET_CHECKED = 2;
private static final int MSG_ATTACH_LISTENER = 3;
private static final int MSG_DETACH_LISTENER = 4;
private static final int MSG_VR_MODE_CHANGED = 5;
private final int mMinimumBacklight;
private final int mMaximumBacklight;
private final int mMinimumBacklightForVr;
private final int mMaximumBacklightForVr;
private final Context mContext;
private final ImageView mIcon;
private final ToggleSlider mControl;
private final boolean mAutomaticAvailable;
private final IPowerManager mPower;
private final CurrentUserTracker mUserTracker;
private final IVrManager mVrManager;
private Handler mBackgroundHandler;
private final BrightnessObserver mBrightnessObserver;
private ArrayList<BrightnessStateChangeCallback> mChangeCallbacks =
new ArrayList<BrightnessStateChangeCallback>();
private volatile boolean mAutomatic; // Brightness adjusted automatically using ambient light.
private volatile boolean mIsVrModeEnabled;
private boolean mListening;
private boolean mExternalChange;
public interface BrightnessStateChangeCallback {
public void onBrightnessLevelChanged();
}
/** ContentObserver to watch brightness **/
private class BrightnessObserver extends ContentObserver {
private final Uri BRIGHTNESS_MODE_URI =
Settings.System.getUriFor(Settings.System.SCREEN_BRIGHTNESS_MODE);
private final Uri BRIGHTNESS_URI =
Settings.System.getUriFor(Settings.System.SCREEN_BRIGHTNESS);
private final Uri BRIGHTNESS_FOR_VR_URI =
Settings.System.getUriFor(Settings.System.SCREEN_BRIGHTNESS_FOR_VR);
private final Uri BRIGHTNESS_ADJ_URI =
Settings.System.getUriFor(Settings.System.SCREEN_AUTO_BRIGHTNESS_ADJ);
public BrightnessObserver(Handler handler) {
super(handler);
}
@Override
public void onChange(boolean selfChange) {
onChange(selfChange, null);
}
@Override
public void onChange(boolean selfChange, Uri uri) {
if (selfChange) return;
if (BRIGHTNESS_MODE_URI.equals(uri)) {
mBackgroundHandler.post(mUpdateModeRunnable);
mBackgroundHandler.post(mUpdateSliderRunnable);
} else if (BRIGHTNESS_URI.equals(uri) && !mAutomatic) {
mBackgroundHandler.post(mUpdateSliderRunnable);
} else if (BRIGHTNESS_FOR_VR_URI.equals(uri)) {
mBackgroundHandler.post(mUpdateSliderRunnable);
} else if (BRIGHTNESS_ADJ_URI.equals(uri) && mAutomatic) {
mBackgroundHandler.post(mUpdateSliderRunnable);
} else {
mBackgroundHandler.post(mUpdateModeRunnable);
mBackgroundHandler.post(mUpdateSliderRunnable);
}
for (BrightnessStateChangeCallback cb : mChangeCallbacks) {
cb.onBrightnessLevelChanged();
}
}
public void startObserving() {
final ContentResolver cr = mContext.getContentResolver();
cr.unregisterContentObserver(this);
cr.registerContentObserver(
BRIGHTNESS_MODE_URI,
false, this, UserHandle.USER_ALL);
cr.registerContentObserver(
BRIGHTNESS_URI,
false, this, UserHandle.USER_ALL);
cr.registerContentObserver(
BRIGHTNESS_FOR_VR_URI,
false, this, UserHandle.USER_ALL);
cr.registerContentObserver(
BRIGHTNESS_ADJ_URI,
false, this, UserHandle.USER_ALL);
}
public void stopObserving() {
final ContentResolver cr = mContext.getContentResolver();
cr.unregisterContentObserver(this);
}
}
private final Runnable mStartListeningRunnable = new Runnable() {
@Override
public void run() {
mBrightnessObserver.startObserving();
mUserTracker.startTracking();
// Update the slider and mode before attaching the listener so we don't
// receive the onChanged notifications for the initial values.
mUpdateModeRunnable.run();
mUpdateSliderRunnable.run();
mHandler.sendEmptyMessage(MSG_ATTACH_LISTENER);
}
};
private final Runnable mStopListeningRunnable = new Runnable() {
@Override
public void run() {
mBrightnessObserver.stopObserving();
mUserTracker.stopTracking();
mHandler.sendEmptyMessage(MSG_DETACH_LISTENER);
}
};
/**
* Fetch the brightness mode from the system settings and update the icon. Should be called from
* background thread.
*/
private final Runnable mUpdateModeRunnable = new Runnable() {
@Override
public void run() {
if (mAutomaticAvailable) {
int automatic;
automatic = Settings.System.getIntForUser(mContext.getContentResolver(),
Settings.System.SCREEN_BRIGHTNESS_MODE,
Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL,
UserHandle.USER_CURRENT);
mAutomatic = automatic != Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL;
mHandler.obtainMessage(MSG_UPDATE_ICON, mAutomatic ? 1 : 0).sendToTarget();
} else {
mHandler.obtainMessage(MSG_SET_CHECKED, 0).sendToTarget();
mHandler.obtainMessage(MSG_UPDATE_ICON, 0 /* automatic */).sendToTarget();
}
}
};
/**
* Fetch the brightness from the system settings and update the slider. Should be called from
* background thread.
*/
private final Runnable mUpdateSliderRunnable = new Runnable() {
@Override
public void run() {
if (mIsVrModeEnabled) {
int value = Settings.System.getIntForUser(mContext.getContentResolver(),
Settings.System.SCREEN_BRIGHTNESS_FOR_VR, mMaximumBacklight,
UserHandle.USER_CURRENT);
mHandler.obtainMessage(MSG_UPDATE_SLIDER,
mMaximumBacklightForVr - mMinimumBacklightForVr,
value - mMinimumBacklightForVr).sendToTarget();
} else if (mAutomatic) {
float value = Settings.System.getFloatForUser(mContext.getContentResolver(),
Settings.System.SCREEN_AUTO_BRIGHTNESS_ADJ, 0,
UserHandle.USER_CURRENT);
mHandler.obtainMessage(MSG_UPDATE_SLIDER, (int) BRIGHTNESS_ADJ_RESOLUTION,
(int) ((value + 1) * BRIGHTNESS_ADJ_RESOLUTION / 2f)).sendToTarget();
} else {
int value;
value = Settings.System.getIntForUser(mContext.getContentResolver(),
Settings.System.SCREEN_BRIGHTNESS, mMaximumBacklight,
UserHandle.USER_CURRENT);
mHandler.obtainMessage(MSG_UPDATE_SLIDER, mMaximumBacklight - mMinimumBacklight,
value - mMinimumBacklight).sendToTarget();
}
}
};
private final IVrStateCallbacks mVrStateCallbacks = new IVrStateCallbacks.Stub() {
@Override
public void onVrStateChanged(boolean enabled) {
mHandler.obtainMessage(MSG_VR_MODE_CHANGED, enabled ? 1 : 0, 0)
.sendToTarget();
}
};
private final Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
mExternalChange = true;
try {
switch (msg.what) {
case MSG_UPDATE_ICON:
updateIcon(msg.arg1 != 0);
break;
case MSG_UPDATE_SLIDER:
mControl.setMax(msg.arg1);
mControl.setValue(msg.arg2);
break;
case MSG_SET_CHECKED:
mControl.setChecked(msg.arg1 != 0);
break;
case MSG_ATTACH_LISTENER:
mControl.setOnChangedListener(BrightnessController.this);
break;
case MSG_DETACH_LISTENER:
mControl.setOnChangedListener(null);
break;
case MSG_VR_MODE_CHANGED:
updateVrMode(msg.arg1 != 0);
break;
default:
super.handleMessage(msg);
}
} finally {
mExternalChange = false;
}
}
};
public BrightnessController(Context context, ImageView icon, ToggleSlider control) {
mContext = context;
mIcon = icon;
mControl = control;
mBackgroundHandler = new Handler(Looper.getMainLooper());
mUserTracker = new CurrentUserTracker(mContext) {
@Override
public void onUserSwitched(int newUserId) {
mBackgroundHandler.post(mUpdateModeRunnable);
mBackgroundHandler.post(mUpdateSliderRunnable);
}
};
mBrightnessObserver = new BrightnessObserver(mHandler);
PowerManager pm = (PowerManager)context.getSystemService(Context.POWER_SERVICE);
mMinimumBacklight = pm.getMinimumScreenBrightnessSetting();
mMaximumBacklight = pm.getMaximumScreenBrightnessSetting();
mMinimumBacklightForVr = pm.getMinimumScreenBrightnessForVrSetting();
mMaximumBacklightForVr = pm.getMaximumScreenBrightnessForVrSetting();
mAutomaticAvailable = context.getResources().getBoolean(
com.android.internal.R.bool.config_automatic_brightness_available);
mPower = IPowerManager.Stub.asInterface(ServiceManager.getService("power"));
mVrManager = IVrManager.Stub.asInterface(ServiceManager.getService("vrmanager"));
}
public void setBackgroundLooper(Looper backgroundLooper) {
mBackgroundHandler = new Handler(backgroundLooper);
}
public void addStateChangedCallback(BrightnessStateChangeCallback cb) {
mChangeCallbacks.add(cb);
}
public boolean removeStateChangedCallback(BrightnessStateChangeCallback cb) {
return mChangeCallbacks.remove(cb);
}
@Override
public void onInit(ToggleSlider control) {
// Do nothing
}
public void registerCallbacks() {
if (mListening) {
return;
}
if (mVrManager != null) {
try {
mVrManager.registerListener(mVrStateCallbacks);
mIsVrModeEnabled = mVrManager.getVrModeState();
} catch (RemoteException e) {
Log.e(TAG, "Failed to register VR mode state listener: ", e);
}
}
mBackgroundHandler.post(mStartListeningRunnable);
mListening = true;
}
/** Unregister all call backs, both to and from the controller */
public void unregisterCallbacks() {
if (!mListening) {
return;
}
if (mVrManager != null) {
try {
mVrManager.unregisterListener(mVrStateCallbacks);
} catch (RemoteException e) {
Log.e(TAG, "Failed to unregister VR mode state listener: ", e);
}
}
mBackgroundHandler.post(mStopListeningRunnable);
mListening = false;
}
@Override
public void onChanged(ToggleSlider view, boolean tracking, boolean automatic, int value,
boolean stopTracking) {
updateIcon(mAutomatic);
Log.e("fjasmin","：onChanged Backlight ："+ value);
if (mExternalChange) return;
if (mIsVrModeEnabled) {
Log.e("fjasmin","------------ACTION_BRIGHTNESS_FOR_VR------------------");
final int val = value + mMinimumBacklightForVr;
if (stopTracking) {
MetricsLogger.action(mContext, MetricsEvent.ACTION_BRIGHTNESS_FOR_VR, val);
}
setBrightness(val);
if (!tracking) {
AsyncTask.execute(new Runnable() {
public void run() {
Settings.System.putIntForUser(mContext.getContentResolver(),
Settings.System.SCREEN_BRIGHTNESS_FOR_VR, val,
UserHandle.USER_CURRENT);
}
});
}
} else if (!mAutomatic) {
Log.e("fjasmin","------------ACTION_BRIGHTNESS------------------");
final int val = value + mMinimumBacklight;
if (stopTracking) {
MetricsLogger.action(mContext, MetricsEvent.ACTION_BRIGHTNESS, val);
}
setBrightness(val);
if (!tracking) {
AsyncTask.execute(new Runnable() {
public void run() {
Settings.System.putIntForUser(mContext.getContentResolver(),
Settings.System.SCREEN_BRIGHTNESS, val,
UserHandle.USER_CURRENT);
}
});
}
} else {
Log.e("fjasmin","------------ACTION_BRIGHTNESS_AUTO------------------");
final float adj = value / (BRIGHTNESS_ADJ_RESOLUTION / 2f) - 1;
if (stopTracking) {
MetricsLogger.action(mContext, MetricsEvent.ACTION_BRIGHTNESS_AUTO, value);
}
setBrightnessAdj(adj);
if (!tracking) {
AsyncTask.execute(new Runnable() {
public void run() {
Settings.System.putFloatForUser(mContext.getContentResolver(),
Settings.System.SCREEN_AUTO_BRIGHTNESS_ADJ, adj,
UserHandle.USER_CURRENT);
}
});
}
}
for (BrightnessStateChangeCallback cb : mChangeCallbacks) {
cb.onBrightnessLevelChanged();
}
}
private void setMode(int mode) {
Settings.System.putIntForUser(mContext.getContentResolver(),
Settings.System.SCREEN_BRIGHTNESS_MODE, mode,
mUserTracker.getCurrentUserId());
}
private void setBrightness(int brightness) {
try {
mPower.setTemporaryScreenBrightnessSettingOverride(brightness);
} catch (RemoteException ex) {
}
}
private void setBrightnessAdj(float adj) {
try {
mPower.setTemporaryScreenAutoBrightnessAdjustmentSettingOverride(adj);
} catch (RemoteException ex) {
}
}
private void updateIcon(boolean automatic) {
if (mIcon != null) {
mIcon.setImageResource(automatic && SHOW_AUTOMATIC_ICON ?
com.android.systemui.R.drawable.ic_qs_brightness_auto_on :
com.android.systemui.R.drawable.ic_qs_brightness_auto_off);
}
}
private void updateVrMode(boolean isEnabled) {
if (mIsVrModeEnabled != isEnabled) {
mIsVrModeEnabled = isEnabled;
mBackgroundHandler.post(mUpdateSliderRunnable);
}
}
}
private void updateSlider(int val, boolean inVrMode) {
final int min;
final int max;
if (inVrMode) {
min = mMinimumBacklightForVr;
max = mMaximumBacklightForVr;
} else {
min = mMinimumBacklight;
max = mMaximumBacklight;
}
if (val == convertGammaToLinear(mControl.getValue(), min, max)) {
// If we have more resolution on the slider than we do in the actual setting, then
// multiple slider positions will map to the same setting value. Thus, if we see a
// setting value here that maps to the current slider position, we don't bother to
// calculate the new slider position since it may differ and look like a brightness
// change to the user even though it isn't one.
return;
}
final int sliderVal = convertLinearToGamma(val, min, max);
animateSliderTo(sliderVal);
}
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