DeskClock: Use accelerometer instead of orientation sensor

Orientation sensor is deprecated, and usually it requires
devices to have magnetic sensor for orientation sensor
to be available. For flip action, we can just use accelerometer
instead. Solve the problem that flip to action is not available
for device without a magnetic sensor.

FEIJ-539

Change-Id: I716bf5d43a4042bc4da5d8e68126f52974fb1e7d

1 files changed, 46 insertions, 33 deletions

diff --git a/src/com/android/deskclock/alarms/AlarmService.java b/src/com/android/deskclock/alarms/AlarmService.java
index 67ae139be..83c2f57a7 100644
--- a/src/com/android/deskclock/alarms/AlarmService.java
+++ b/src/com/android/deskclock/alarms/AlarmService.java
@@ -288,15 +288,18 @@ public class AlarmService extends Service {
         }
     }
 
-    private final SensorEventListener mFlipListener = new SensorEventListener() {
-        private static final int FACE_UP_LOWER_LIMIT = -45;
-        private static final int FACE_UP_UPPER_LIMIT = 45;
-        private static final int FACE_DOWN_UPPER_LIMIT = 135;
-        private static final int FACE_DOWN_LOWER_LIMIT = -135;
-        private static final int TILT_UPPER_LIMIT = 45;
-        private static final int TILT_LOWER_LIMIT = -45;
+    private interface ResettableSensorEventListener extends SensorEventListener {
+        public void reset();
+    }
+
+    private final ResettableSensorEventListener mFlipListener =
+        new ResettableSensorEventListener() {
+        // Accelerometers are not quite accurate.
+        private static final float GRAVITY_UPPER_THRESHOLD = 1.3f * SensorManager.STANDARD_GRAVITY;
+        private static final float GRAVITY_LOWER_THRESHOLD = 0.7f * SensorManager.STANDARD_GRAVITY;
         private static final int SENSOR_SAMPLES = 3;
 
+        private boolean mStopped;
         private boolean mWasFaceUp;
         private boolean[] mSamples = new boolean[SENSOR_SAMPLES];
         private int mSampleIndex;
@@ -306,44 +309,53 @@ public class AlarmService extends Service {
         }
 
         @Override
+        public void reset() {
+            mWasFaceUp = false;
+            mStopped = false;
+            for (int i = 0; i < SENSOR_SAMPLES; i++) {
+                mSamples[i] = false;
+            }
+        }
+
+        private boolean filterSamples() {
+            boolean allPass = true;
+            for (boolean sample : mSamples) {
+                allPass = allPass && sample;
+            }
+            return allPass;
+        }
+
+        @Override
         public void onSensorChanged(SensorEvent event) {
             // Add a sample overwriting the oldest one. Several samples
-            // are used
-            // to avoid the erroneous values the sensor sometimes
+            // are used to avoid the erroneous values the sensor sometimes
             // returns.
-            float y = event.values[1];
             float z = event.values[2];
 
+            if (mStopped) {
+                return;
+            }
+
             if (!mWasFaceUp) {
                 // Check if its face up enough.
-                mSamples[mSampleIndex] = y > FACE_UP_LOWER_LIMIT
-                        && y < FACE_UP_UPPER_LIMIT
-                        && z > TILT_LOWER_LIMIT && z < TILT_UPPER_LIMIT;
-
-                // The device first needs to be face up.
-                boolean faceUp = true;
-                for (boolean sample : mSamples) {
-                    faceUp = faceUp && sample;
-                }
-                if (faceUp) {
+                mSamples[mSampleIndex] = (z > GRAVITY_LOWER_THRESHOLD) &&
+                    (z < GRAVITY_UPPER_THRESHOLD);
+
+                // face up
+                if (filterSamples()) {
                     mWasFaceUp = true;
                     for (int i = 0; i < SENSOR_SAMPLES; i++) {
                         mSamples[i] = false;
                     }
                 }
             } else {
-                // Check if its face down enough. Note that wanted
-                // values go from FACE_DOWN_UPPER_LIMIT to 180
-                // and from -180 to FACE_DOWN_LOWER_LIMIT
-                mSamples[mSampleIndex] = (y > FACE_DOWN_UPPER_LIMIT || y < FACE_DOWN_LOWER_LIMIT)
-                        && z > TILT_LOWER_LIMIT
-                        && z < TILT_UPPER_LIMIT;
-
-                boolean faceDown = true;
-                for (boolean sample : mSamples) {
-                    faceDown = faceDown && sample;
-                }
-                if (faceDown) {
+                // Check if its face down enough.
+                mSamples[mSampleIndex] = (z < -GRAVITY_LOWER_THRESHOLD) &&
+                    (z > -GRAVITY_UPPER_THRESHOLD);
+
+                // face down
+                if (filterSamples()) {
+                    mStopped = true;
                     handleAction(mFlipAction);
                 }
             }
@@ -389,8 +401,9 @@ public class AlarmService extends Service {
 
     private void attachListeners() {
         if (mFlipAction != ALARM_NO_ACTION) {
+            mFlipListener.reset();
             mSensorManager.registerListener(mFlipListener,
-                    mSensorManager.getDefaultSensor(Sensor.TYPE_ORIENTATION),
+                    mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER),
                     SensorManager.SENSOR_DELAY_NORMAL,
                     300 * 1000); //batch every 300 milliseconds
         }