1 /* 2 * Copyright (C) 2012 ZXing authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.google.zxing.client.android; 18 19 import android.content.Context; 20 import android.content.SharedPreferences; 21 import android.hardware.Sensor; 22 import android.hardware.SensorEvent; 23 import android.hardware.SensorEventListener; 24 import android.hardware.SensorManager; 25 import android.preference.PreferenceManager; 26 import com.google.zxing.client.android.camera.CameraManager; 27 import com.google.zxing.client.android.camera.FrontLightMode; 28 29 /** 30 * Detects ambient light and switches on the front light when very dark, and off again when sufficiently light. 31 * 32 * @author Sean Owen 33 * @author Nikolaus Huber 34 */ 35 final class AmbientLightManager implements SensorEventListener { 36 37 private static final float TOO_DARK_LUX = 45.0f; 38 private static final float BRIGHT_ENOUGH_LUX = 450.0f; 39 40 private final Context context; 41 private CameraManager cameraManager; 42 private Sensor lightSensor; 43 AmbientLightManager(Context context)44 AmbientLightManager(Context context) { 45 this.context = context; 46 } 47 start(CameraManager cameraManager)48 void start(CameraManager cameraManager) { 49 this.cameraManager = cameraManager; 50 SharedPreferences sharedPrefs = PreferenceManager.getDefaultSharedPreferences(context); 51 if (FrontLightMode.readPref(sharedPrefs) == FrontLightMode.AUTO) { 52 SensorManager sensorManager = (SensorManager) context.getSystemService(Context.SENSOR_SERVICE); 53 lightSensor = sensorManager.getDefaultSensor(Sensor.TYPE_LIGHT); 54 if (lightSensor != null) { 55 sensorManager.registerListener(this, lightSensor, SensorManager.SENSOR_DELAY_NORMAL); 56 } 57 } 58 } 59 stop()60 void stop() { 61 if (lightSensor != null) { 62 SensorManager sensorManager = (SensorManager) context.getSystemService(Context.SENSOR_SERVICE); 63 sensorManager.unregisterListener(this); 64 cameraManager = null; 65 lightSensor = null; 66 } 67 } 68 69 @Override onSensorChanged(SensorEvent sensorEvent)70 public void onSensorChanged(SensorEvent sensorEvent) { 71 float ambientLightLux = sensorEvent.values[0]; 72 if (cameraManager != null) { 73 if (ambientLightLux <= TOO_DARK_LUX) { 74 cameraManager.setTorch(true); 75 } else if (ambientLightLux >= BRIGHT_ENOUGH_LUX) { 76 cameraManager.setTorch(false); 77 } 78 } 79 } 80 81 @Override onAccuracyChanged(Sensor sensor, int accuracy)82 public void onAccuracyChanged(Sensor sensor, int accuracy) { 83 // do nothing 84 } 85 86 } 87