Listen to brigtness updates to update brightness summary.

- add content observer for brightness relates changes, and update the
brightness preference summary when changes occur.
- also check for VR mode and auto brightness mode when reading the
current brightness value.

Change-Id: I611ec77174ab45315ccbee2952bdbc2c9a9cd954
Fix: 37227609
Test: make RunSettingsRoboTests

src/com/android/settings/display/BrightnessLevelPreferenceController.java

@@ -0,0 +1,166 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the
+ * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+package com.android.settings.display;
+
+import android.content.ContentResolver;
+import android.content.Context;
+import android.database.ContentObserver;
+import android.net.Uri;
+import android.os.Handler;
+import android.os.Looper;
+import android.os.PowerManager;
+import android.os.RemoteException;
+import android.os.ServiceManager;
+import android.provider.Settings;
+import android.provider.Settings.System;
+import android.service.vr.IVrManager;
+import android.support.annotation.VisibleForTesting;
+import android.support.v7.preference.Preference;
+import android.support.v7.preference.PreferenceScreen;
+import android.util.Log;
+
+import com.android.settings.core.PreferenceController;
+import com.android.settings.core.lifecycle.Lifecycle;
+import com.android.settings.core.lifecycle.LifecycleObserver;
+import com.android.settings.core.lifecycle.events.OnPause;
+import com.android.settings.core.lifecycle.events.OnResume;
+
+import java.text.NumberFormat;
+
+public class BrightnessLevelPreferenceController extends PreferenceController implements
+        LifecycleObserver, OnResume, OnPause {
+
+    private static final String TAG = "BrightnessPrefCtrl";
+    private static final String KEY_BRIGHTNESS = "brightness";
+    private static final Uri BRIGHTNESS_MODE_URI;
+    private static final Uri BRIGHTNESS_URI;
+    private static final Uri BRIGHTNESS_FOR_VR_URI;
+    private static final Uri BRIGHTNESS_ADJ_URI;
+
+    private final int mMinBrightness;
+    private final int mMaxBrightness;
+    private final int mMinVrBrightness;
+    private final int mMaxVrBrightness;
+    private final ContentResolver mContentResolver;
+
+    private Preference mPreference;
+
+    static {
+        BRIGHTNESS_MODE_URI = System.getUriFor(System.SCREEN_BRIGHTNESS_MODE);
+        BRIGHTNESS_URI = System.getUriFor(System.SCREEN_BRIGHTNESS);
+        BRIGHTNESS_FOR_VR_URI = System.getUriFor(System.SCREEN_BRIGHTNESS_FOR_VR);
+        BRIGHTNESS_ADJ_URI = System.getUriFor(System.SCREEN_AUTO_BRIGHTNESS_ADJ);
+    }
+
+    private ContentObserver mBrightnessObserver =
+        new ContentObserver(new Handler(Looper.getMainLooper())) {
+            @Override
+            public void onChange(boolean selfChange) {
+                updatedSummary(mPreference);
+            }
+        };
+
+    public BrightnessLevelPreferenceController(Context context, Lifecycle lifecycle) {
+        this(context, lifecycle, new PowerManagerWrapper(
+                (PowerManager) context.getSystemService(Context.POWER_SERVICE)));
+    }
+
+    @VisibleForTesting
+    public BrightnessLevelPreferenceController(Context context, Lifecycle lifecycle,
+            PowerManagerWrapper powerManagerWrapper) {
+        super(context);
+        if (lifecycle != null) {
+            lifecycle.addObserver(this);
+        }
+        mMinBrightness = powerManagerWrapper.getMinimumScreenBrightnessSetting();
+        mMaxBrightness = powerManagerWrapper.getMaximumScreenBrightnessSetting();
+        mMinVrBrightness = powerManagerWrapper.getMinimumScreenBrightnessForVrSetting();
+        mMaxVrBrightness = powerManagerWrapper.getMaximumScreenBrightnessForVrSetting();
+        mContentResolver = mContext.getContentResolver();
+    }
+
+    @Override
+    public boolean isAvailable() {
+        return true;
+    }
+
+    @Override
+    public String getPreferenceKey() {
+        return KEY_BRIGHTNESS;
+    }
+
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+        mPreference = screen.findPreference(KEY_BRIGHTNESS);
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        updatedSummary(preference);
+    }
+
+    @Override
+    public void onResume() {
+        mContentResolver.registerContentObserver(BRIGHTNESS_MODE_URI, false, mBrightnessObserver);
+        mContentResolver.registerContentObserver(BRIGHTNESS_URI, false, mBrightnessObserver);
+        mContentResolver.registerContentObserver(BRIGHTNESS_FOR_VR_URI, false, mBrightnessObserver);
+        mContentResolver.registerContentObserver(BRIGHTNESS_ADJ_URI, false, mBrightnessObserver);
+    }
+
+    @Override
+    public void onPause() {
+        mContentResolver.unregisterContentObserver(mBrightnessObserver);
+    }
+
+    private void updatedSummary(Preference preference) {
+        if (preference != null) {
+            preference.setSummary(NumberFormat.getPercentInstance().format(getCurrentBrightness()));
+        }
+    }
+
+    private double getCurrentBrightness() {
+        if (isInVrMode()) {
+            final double value = System.getInt(mContentResolver, System.SCREEN_BRIGHTNESS_FOR_VR,
+                    mMaxBrightness);
+            return getPercentage(value, mMinVrBrightness, mMaxVrBrightness);
+        }
+        final int brightnessMode = Settings.System.getInt(mContentResolver,
+                System.SCREEN_BRIGHTNESS_MODE, System.SCREEN_BRIGHTNESS_MODE_MANUAL);
+        if (brightnessMode == System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC) {
+            final float value = Settings.System.getFloat(mContentResolver,
+                    System.SCREEN_AUTO_BRIGHTNESS_ADJ, 0);
+            // auto brightness is between -1 and 1
+            return ((value + 1)) / 2;
+        }
+        final double value = Settings.System.getInt(mContentResolver, System.SCREEN_BRIGHTNESS,
+                mMinBrightness);
+        return getPercentage(value, mMinBrightness, mMaxBrightness);
+    }
+
+    private double getPercentage(double value, int min, int max) {
+        return (value - min) / (max - min);
+    }
+
+    @VisibleForTesting
+    boolean isInVrMode() {
+        try {
+            return IVrManager.Stub.asInterface(ServiceManager.getService(Context.VR_SERVICE))
+                    .getVrModeState();
+        } catch (RemoteException e) {
+            Log.e(TAG, "Failed to check vr mode!", e);
+        }
+        return false;
+    }
+}