Add hysteresis to orientation rounding.

This prevents fast flickering between two orientation states, which
can result in ugly UI issues, especially with the preview thumbnail.

Bug: 5477483
Change-Id: I9513547207ae1918066c1a19947c974eaad72e24

4 files changed, 21 insertions, 14 deletions

diff --git a/src/com/android/camera/Camera.java b/src/com/android/camera/Camera.java
index 685319f..589a5c8 100644
--- a/src/com/android/camera/Camera.java
+++ b/src/com/android/camera/Camera.java
@@ -1184,10 +1184,6 @@ public class Camera extends ActivityBase implements FocusManager.Listener,
         if (mThumbnailView != null) mThumbnailView.setEnabled(enable);
     }
 
-    public static int roundOrientation(int orientation) {
-        return ((orientation + 45) / 90 * 90) % 360;
-    }
-
     private class MyOrientationEventListener
             extends OrientationEventListener {
         public MyOrientationEventListener(Context context) {
@@ -1200,7 +1196,7 @@ public class Camera extends ActivityBase implements FocusManager.Listener,
             // the camera then point the camera to floor or sky, we still have
             // the correct orientation.
             if (orientation == ORIENTATION_UNKNOWN) return;
-            mOrientation = roundOrientation(orientation);
+            mOrientation = Util.roundOrientation(orientation, mOrientation);
             // When the screen is unlocked, display rotation may change. Always
             // calculate the up-to-date orientationCompensation.
             int orientationCompensation = mOrientation
diff --git a/src/com/android/camera/Util.java b/src/com/android/camera/Util.java
index 768bf27..31a54d5 100644
--- a/src/com/android/camera/Util.java
+++ b/src/com/android/camera/Util.java
@@ -71,6 +71,9 @@ public class Util {
     // Use the same setting among the Camera, VideoCamera and Panorama modes.
     private static final float DEFAULT_CAMERA_BRIGHTNESS = 0.7f;
 
+    // Orientation hysteresis amount used in rounding, in degrees
+    public static final int ORIENTATION_HYSTERESIS = 5;
+
     public static final String REVIEW_ACTION = "com.android.camera.action.REVIEW";
 
     // Private intent extras. Test only.
@@ -345,6 +348,21 @@ public class Util {
         return result;
     }
 
+    public static int roundOrientation(int orientation, int orientationHistory) {
+        boolean changeOrientation = false;
+        if (orientationHistory == OrientationEventListener.ORIENTATION_UNKNOWN) {
+            changeOrientation = true;
+        } else {
+            int dist = Math.abs(orientation - orientationHistory);
+            dist = Math.min( dist, 360 - dist );
+            changeOrientation = ( dist >= 45 + ORIENTATION_HYSTERESIS );
+        }
+        if (changeOrientation) {
+            return ((orientation + 45) / 90 * 90) % 360;
+        }
+        return orientationHistory;
+    }
+
     public static Size getOptimalPreviewSize(Activity currentActivity,
             List<Size> sizes, double targetRatio) {
         // Use a very small tolerance because we want an exact match.
diff --git a/src/com/android/camera/VideoCamera.java b/src/com/android/camera/VideoCamera.java
index df8adb9..6b1ed1d 100755
--- a/src/com/android/camera/VideoCamera.java
+++ b/src/com/android/camera/VideoCamera.java
@@ -500,9 +500,6 @@ public class VideoCamera extends ActivityBase
         }
     }
 
-    public static int roundOrientation(int orientation) {
-        return ((orientation + 45) / 90 * 90) % 360;
-    }
 
     private class MyOrientationEventListener
             extends OrientationEventListener {
@@ -516,7 +513,7 @@ public class VideoCamera extends ActivityBase
             // the camera then point the camera to floor or sky, we still have
             // the correct orientation.
             if (orientation == ORIENTATION_UNKNOWN) return;
-            mOrientation = roundOrientation(orientation);
+            mOrientation = Util.roundOrientation(orientation, mOrientation);
             // When the screen is unlocked, display rotation may change. Always
             // calculate the up-to-date orientationCompensation.
             int orientationCompensation = mOrientation
diff --git a/src/com/android/camera/panorama/PanoramaActivity.java b/src/com/android/camera/panorama/PanoramaActivity.java
index 25c565f..c28cc2e 100755
--- a/src/com/android/camera/panorama/PanoramaActivity.java
+++ b/src/com/android/camera/panorama/PanoramaActivity.java
@@ -190,10 +190,6 @@ public class PanoramaActivity extends ActivityBase implements
         public final boolean isValid;
     }
 
-    public static int roundOrientation(int orientation) {
-        return ((orientation + 45) / 90 * 90) % 360;
-    }
-
     private class PanoOrientationEventListener extends OrientationEventListener {
         public PanoOrientationEventListener(Context context) {
             super(context);
@@ -205,7 +201,7 @@ public class PanoramaActivity extends ActivityBase implements
             // the camera then point the camera to floor or sky, we still have
             // the correct orientation.
             if (orientation == ORIENTATION_UNKNOWN) return;
-            mDeviceOrientation = roundOrientation(orientation);
+            mDeviceOrientation = Util.roundOrientation(orientation, mDeviceOrientation);
             // When the screen is unlocked, display rotation may change. Always
             // calculate the up-to-date orientationCompensation.
             int orientationCompensation = mDeviceOrientation