Animating Markers

1MarkerAnimation.java

/* Copyright 2013 Google Inc.
   Licensed under Apache 2.0: http://www.apache.org/licenses/LICENSE-2.0.html */

package com.example.latlnginterpolation;

import android.animation.ObjectAnimator;
import android.animation.TypeEvaluator;
import android.animation.ValueAnimator;
import android.annotation.TargetApi;
import android.os.Build;
import android.os.Handler;
import android.os.SystemClock;
import android.util.Property;
import android.view.animation.AccelerateDecelerateInterpolator;
import android.view.animation.Interpolator;

import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.Marker;

public class MarkerAnimation {
    static void animateMarkerToGB(final Marker marker, final LatLng finalPosition, final LatLngInterpolator latLngInterpolator) {
        final LatLng startPosition = marker.getPosition();
        final Handler handler = new Handler();
        final long start = SystemClock.uptimeMillis();
        final Interpolator interpolator = new AccelerateDecelerateInterpolator();
        final float durationInMs = 3000;

        handler.post(new Runnable() {
            long elapsed;
            float t;
            float v;

            @Override
            public void run() {
                // Calculate progress using interpolator
                elapsed = SystemClock.uptimeMillis() - start;
                t = elapsed / durationInMs;
                v = interpolator.getInterpolation(t);

                marker.setPosition(latLngInterpolator.interpolate(v, startPosition, finalPosition));

                // Repeat till progress is complete.
                if (t < 1) {
                    // Post again 16ms later.
                    handler.postDelayed(this, 16);
                }
            }
        });
    }

    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    static void animateMarkerToHC(final Marker marker, final LatLng finalPosition, final LatLngInterpolator latLngInterpolator) {
        final LatLng startPosition = marker.getPosition();

        ValueAnimator valueAnimator = new ValueAnimator();
        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator animation) {
                float v = animation.getAnimatedFraction();
                LatLng newPosition = latLngInterpolator.interpolate(v, startPosition, finalPosition);
                marker.setPosition(newPosition);
            }
        });
        valueAnimator.setFloatValues(0, 1); // Ignored.
        valueAnimator.setDuration(3000);
        valueAnimator.start();
    }

    @TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH)
    static void animateMarkerToICS(Marker marker, LatLng finalPosition, final LatLngInterpolator latLngInterpolator) {
        TypeEvaluator<LatLng> typeEvaluator = new TypeEvaluator<LatLng>() {
            @Override
            public LatLng evaluate(float fraction, LatLng startValue, LatLng endValue) {
                return latLngInterpolator.interpolate(fraction, startValue, endValue);
            }
        };
        Property<Marker, LatLng> property = Property.of(Marker.class, LatLng.class, "position");
        ObjectAnimator animator = ObjectAnimator.ofObject(marker, property, typeEvaluator, finalPosition);
        animator.setDuration(3000);
        animator.start();
    }
}

2LatLngInterpolator.java

/* Copyright 2013 Google Inc.
   Licensed under Apache 2.0: http://www.apache.org/licenses/LICENSE-2.0.html */

package com.example.latlnginterpolation;

import com.google.android.gms.maps.model.LatLng;

import static java.lang.Math.asin;
import static java.lang.Math.atan2;
import static java.lang.Math.cos;
import static java.lang.Math.pow;
import static java.lang.Math.sin;
import static java.lang.Math.sqrt;
import static java.lang.Math.toDegrees;
import static java.lang.Math.toRadians;

public interface LatLngInterpolator {
    public LatLng interpolate(float fraction, LatLng a, LatLng b);

    public class Linear implements LatLngInterpolator {
        @Override
        public LatLng interpolate(float fraction, LatLng a, LatLng b) {
            double lat = (b.latitude - a.latitude) * fraction + a.latitude;
            double lng = (b.longitude - a.longitude) * fraction + a.longitude;
            return new LatLng(lat, lng);
        }
    }

    public class LinearFixed implements LatLngInterpolator {
        @Override
        public LatLng interpolate(float fraction, LatLng a, LatLng b) {
            double lat = (b.latitude - a.latitude) * fraction + a.latitude;
            double lngDelta = b.longitude - a.longitude;

            // Take the shortest path across the 180th meridian.
            if (Math.abs(lngDelta) > 180) {
                lngDelta -= Math.signum(lngDelta) * 360;
            }
            double lng = lngDelta * fraction + a.longitude;
            return new LatLng(lat, lng);
        }
    }

    public class Spherical implements LatLngInterpolator {

        /* From github.com/googlemaps/android-maps-utils */
        @Override
        public LatLng interpolate(float fraction, LatLng from, LatLng to) {
            // http://en.wikipedia.org/wiki/Slerp
            double fromLat = toRadians(from.latitude);
            double fromLng = toRadians(from.longitude);
            double toLat = toRadians(to.latitude);
            double toLng = toRadians(to.longitude);
            double cosFromLat = cos(fromLat);
            double cosToLat = cos(toLat);

            // Computes Spherical interpolation coefficients.
            double angle = computeAngleBetween(fromLat, fromLng, toLat, toLng);
            double sinAngle = sin(angle);
            if (sinAngle < 1E-6) {
                return from;
            }
            double a = sin((1 - fraction) * angle) / sinAngle;
            double b = sin(fraction * angle) / sinAngle;

            // Converts from polar to vector and interpolate.
            double x = a * cosFromLat * cos(fromLng) + b * cosToLat * cos(toLng);
            double y = a * cosFromLat * sin(fromLng) + b * cosToLat * sin(toLng);
            double z = a * sin(fromLat) + b * sin(toLat);

            // Converts interpolated vector back to polar.
            double lat = atan2(z, sqrt(x * x + y * y));
            double lng = atan2(y, x);
            return new LatLng(toDegrees(lat), toDegrees(lng));
        }

        private double computeAngleBetween(double fromLat, double fromLng, double toLat, double toLng) {
            // Haversine's formula
            double dLat = fromLat - toLat;
            double dLng = fromLng - toLng;
            return 2 * asin(sqrt(pow(sin(dLat / 2), 2) +
                    cos(fromLat) * cos(toLat) * pow(sin(dLng / 2), 2)));
        }
    }
}