[android] improve rotation inertia, adjust velocity ratios for screen density

3 files changed, 53 insertions, 32 deletions

diff --git a/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/constants/MapboxConstants.java b/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/constants/MapboxConstants.java
index d5c5c4d999..015260322c 100644
--- a/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/constants/MapboxConstants.java
+++ b/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/constants/MapboxConstants.java
@@ -74,11 +74,6 @@ public class MapboxConstants {
   public static final long VELOCITY_THRESHOLD_IGNORE_FLING = 1000;
 
   /**
-   * Value by which the default rotation threshold will be increased when scaling
-   */
-  public static final float ROTATION_THRESHOLD_INCREASE_WHEN_SCALING = 25f;
-
-  /**
    * Maximum absolute zoom change for multi-pointer scale velocity animation
    */
   public static final double MAX_ABSOLUTE_SCALE_VELOCITY_CHANGE = 2.5;
@@ -89,19 +84,24 @@ public class MapboxConstants {
   public static final double SCALE_VELOCITY_ANIMATION_DURATION_MULTIPLIER = 150;
 
   /**
-   * Time within which user needs to lift fingers for velocity animation to start.
+   * Last scale span delta to XY velocity ratio required to execute scale velocity animation.
    */
-  public static final long SCHEDULED_ANIMATION_TIMEOUT = 150L;
+  public static final double SCALE_VELOCITY_RATIO_THRESHOLD = 4 * 1e-3;
 
   /**
-   * Minimum angular velocity for rotation animation
+   * Last rotation delta to XY velocity ratio required to execute rotation velocity animation.
    */
-  public static final float MINIMUM_ANGULAR_VELOCITY = 1.5f;
+  public static final double ROTATE_VELOCITY_RATIO_THRESHOLD = 2.2 * 1e-4;
+
+  /**
+   * Time within which user needs to lift fingers for velocity animation to start.
+   */
+  public static final long SCHEDULED_ANIMATION_TIMEOUT = 150L;
 
   /**
    * Maximum angular velocity for rotation animation
    */
-  public static final float MAXIMUM_ANGULAR_VELOCITY = 20f;
+  public static final float MAXIMUM_ANGULAR_VELOCITY = 30f;
 
   /**
    * Factor to calculate tilt change based on pixel change during shove gesture.
diff --git a/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/maps/MapGestureDetector.java b/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/maps/MapGestureDetector.java
index 6b61f01b8a..80b1e32413 100644
--- a/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/maps/MapGestureDetector.java
+++ b/platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/maps/MapGestureDetector.java
@@ -29,8 +29,11 @@ import java.util.List;
 import java.util.Set;
 import java.util.concurrent.CopyOnWriteArrayList;
 
+import static com.mapbox.mapboxsdk.constants.MapboxConstants.MAXIMUM_ANGULAR_VELOCITY;
 import static com.mapbox.mapboxsdk.constants.MapboxConstants.MAX_ABSOLUTE_SCALE_VELOCITY_CHANGE;
+import static com.mapbox.mapboxsdk.constants.MapboxConstants.ROTATE_VELOCITY_RATIO_THRESHOLD;
 import static com.mapbox.mapboxsdk.constants.MapboxConstants.SCALE_VELOCITY_ANIMATION_DURATION_MULTIPLIER;
+import static com.mapbox.mapboxsdk.constants.MapboxConstants.SCALE_VELOCITY_RATIO_THRESHOLD;
 import static com.mapbox.mapboxsdk.constants.MapboxConstants.ZOOM_RATE;
 import static com.mapbox.mapboxsdk.maps.MapboxMap.OnCameraMoveStartedListener.REASON_API_GESTURE;
 
@@ -114,11 +117,14 @@ final class MapGestureDetector {
           com.mapbox.android.gestures.R.dimen.mapbox_defaultScaleSpanSinceStartThreshold));
       MoveGestureListener moveGestureListener = new MoveGestureListener();
       ScaleGestureListener scaleGestureListener = new ScaleGestureListener(
+        context.getResources().getDimension(R.dimen.mapbox_density_constant),
         context.getResources().getDimension(R.dimen.mapbox_minimum_scale_speed),
         context.getResources().getDimension(R.dimen.mapbox_minimum_angled_scale_speed),
         context.getResources().getDimension(R.dimen.mapbox_minimum_scale_velocity)
       );
       RotateGestureListener rotateGestureListener = new RotateGestureListener(
+        context.getResources().getDimension(R.dimen.mapbox_density_constant),
+        context.getResources().getDimension(R.dimen.mapbox_angular_velocity_multiplier),
         context.getResources().getDimension(R.dimen.mapbox_minimum_angular_velocity));
       ShoveGestureListener shoveGestureListener = new ShoveGestureListener();
       TapGestureListener tapGestureListener = new TapGestureListener();
@@ -258,7 +264,7 @@ final class MapGestureDetector {
   };
 
   /**
-   * Schedules a velocity animator to be executed when user lift fingers,
+   * Schedules a velocity animator to be executed when user lifts fingers,
    * unless canceled by the {@link #cancelAnimatorsRunnable}.
    *
    * @param animator animator ot be scheduled
@@ -483,12 +489,16 @@ final class MapGestureDetector {
     private final float minimumGestureSpeed;
     private final float minimumAngledGestureSpeed;
     private final float minimumVelocity;
+    private final double scaleVelocityRatioThreshold;
     private boolean quickZoom;
+    private float spanSinceLast;
 
-    ScaleGestureListener(float minimumGestureSpeed, float minimumAngledGestureSpeed, float minimumVelocity) {
+    ScaleGestureListener(double densityMultiplier, float minimumGestureSpeed, float minimumAngledGestureSpeed,
+                         float minimumVelocity) {
       this.minimumGestureSpeed = minimumGestureSpeed;
       this.minimumAngledGestureSpeed = minimumAngledGestureSpeed;
       this.minimumVelocity = minimumVelocity;
+      this.scaleVelocityRatioThreshold = SCALE_VELOCITY_RATIO_THRESHOLD * densityMultiplier;
     }
 
     @Override
@@ -539,6 +549,8 @@ final class MapGestureDetector {
 
       notifyOnScaleBeginListeners(detector);
 
+      spanSinceLast = Math.abs(detector.getCurrentSpan() - detector.getPreviousSpan());
+
       return true;
     }
 
@@ -554,6 +566,8 @@ final class MapGestureDetector {
 
       notifyOnScaleListeners(detector);
 
+      spanSinceLast = Math.abs(detector.getCurrentSpan() - detector.getPreviousSpan());
+
       return true;
     }
 
@@ -571,7 +585,9 @@ final class MapGestureDetector {
 
       float velocityXY = Math.abs(velocityX) + Math.abs(velocityY);
 
-      if (!uiSettings.isScaleVelocityAnimationEnabled() || velocityXY < minimumVelocity) {
+      if (!uiSettings.isScaleVelocityAnimationEnabled()
+        || velocityXY < minimumVelocity
+        || spanSinceLast / velocityXY < scaleVelocityRatioThreshold) {
         // notifying listeners that camera is idle only if there is no follow-up animation
         dispatchCameraIdle();
         return;
@@ -625,10 +641,14 @@ final class MapGestureDetector {
   }
 
   private final class RotateGestureListener extends RotateGestureDetector.SimpleOnRotateGestureListener {
+    private final float angularVelocityMultiplier;
     private final float minimumAngularVelocity;
+    private final double rotateVelocityRatioThreshold;
 
-    RotateGestureListener(float minimumAngularVelocity) {
+    RotateGestureListener(double densityMultiplier, float angularVelocityMultiplier, float minimumAngularVelocity) {
+      this.angularVelocityMultiplier = angularVelocityMultiplier;
       this.minimumAngularVelocity = minimumAngularVelocity;
+      this.rotateVelocityRatioThreshold = ROTATE_VELOCITY_RATIO_THRESHOLD * densityMultiplier;
     }
 
     @Override
@@ -685,24 +705,23 @@ final class MapGestureDetector {
                             float velocityY, float angularVelocity) {
       notifyOnRotateEndListeners(detector);
 
-      if (!uiSettings.isRotateVelocityAnimationEnabled() || Math.abs(angularVelocity) < minimumAngularVelocity) {
+      angularVelocity = angularVelocity * angularVelocityMultiplier;
+      angularVelocity = MathUtils.clamp(angularVelocity, -MAXIMUM_ANGULAR_VELOCITY, MAXIMUM_ANGULAR_VELOCITY);
+
+      float velocityXY = Math.abs(velocityX) + Math.abs(velocityY);
+      float delta = Math.abs(detector.getDeltaSinceLast());
+      double ratio = delta / velocityXY;
+
+      if (!uiSettings.isRotateVelocityAnimationEnabled()
+        || Math.abs(angularVelocity) < minimumAngularVelocity
+        || (gesturesManager.getStandardScaleGestureDetector().isInProgress() && ratio < rotateVelocityRatioThreshold)) {
         // notifying listeners that camera is idle only if there is no follow-up animation
         dispatchCameraIdle();
         return;
       }
 
-      boolean negative = angularVelocity < 0;
-      angularVelocity = (float) Math.pow(angularVelocity, 2);
-      angularVelocity = MathUtils.clamp(
-        angularVelocity, MapboxConstants.MINIMUM_ANGULAR_VELOCITY, MapboxConstants.MAXIMUM_ANGULAR_VELOCITY);
-
-      long animationTime = (long) (Math.log(angularVelocity + 1) * 500);
-
-      if (negative) {
-        angularVelocity = -angularVelocity;
-      }
-
-      // todo clear scale velocity if angular velocity exceeds a threshold
+      long animationTime = (long) ((Math.log((Math.abs(angularVelocity)) + 1 / Math.pow(Math.E, 2)) + 2)
+        * SCALE_VELOCITY_ANIMATION_DURATION_MULTIPLIER);
 
       PointF focalPoint = getRotateFocalPoint(detector);
       rotateAnimator = createRotateAnimator(angularVelocity, animationTime, focalPoint);
@@ -929,10 +948,6 @@ final class MapGestureDetector {
       && (!uiSettings.isTiltGesturesEnabled() || !gesturesManager.getShoveGestureDetector().isInProgress());
   }
 
-  private boolean isZoomValid(double mapZoom) {
-    return mapZoom >= MapboxConstants.MINIMUM_ZOOM && mapZoom <= MapboxConstants.MAXIMUM_ZOOM;
-  }
-
   void notifyOnMapClickListeners(@NonNull PointF tapPoint) {
     for (MapboxMap.OnMapClickListener listener : onMapClickListenerList) {
       if (listener.onMapClick(projection.fromScreenLocation(tapPoint))) {
diff --git a/platform/android/MapboxGLAndroidSDK/src/main/res/values/dimens.xml b/platform/android/MapboxGLAndroidSDK/src/main/res/values/dimens.xml
index 018750400c..b2a0061c5b 100644
--- a/platform/android/MapboxGLAndroidSDK/src/main/res/values/dimens.xml
+++ b/platform/android/MapboxGLAndroidSDK/src/main/res/values/dimens.xml
@@ -13,7 +13,13 @@
     <dimen name="mapbox_minimum_scale_velocity">225dp</dimen>
 
     <!--Minimum angular velocity required to start rotation animation-->
-    <dimen name="mapbox_minimum_angular_velocity">0.025dp</dimen>
+    <dimen name="mapbox_minimum_angular_velocity">0.10dp</dimen>
+
+    <!--Angular velocity multiplier. Adapts the velocity for screen density-->
+    <dimen name="mapbox_angular_velocity_multiplier">1.3dp</dimen>
+
+    <!--Screen density constant to adjust gesture's velocityXY thresholds-->
+    <dimen name="mapbox_density_constant">0.29dp</dimen>
 
     <dimen name="mapbox_locationComponentTrackingInitialMoveThreshold">25dp</dimen>
     <dimen name="mapbox_locationComponentTrackingMultiFingerMoveThreshold">400dp</dimen>