从屏幕顶部缓慢拖放标记到android地图V2上的位置

Question

我正在使用android maps v2works,我可以添加和删除onLong Touch上的标记位置.

问题: 我想将标记缓慢地放入触摸位置,即我希望用户看到标记从屏幕顶部漂浮到掉落点(触摸位置).

目前; 标记只出现在触摸位置,这样您就必须抬起手指才能看到它已被掉落.很高兴看到它来自屏幕的顶部.

谢谢.

Answer 1

您可以使用与此类似的代码(未经测试)来实现此目的:

final LatLng target = ...;

final long duration = 400;
final Handler handler = new Handler();
final long start = SystemClock.uptimeMillis();
Projection proj = map.getProjection();

Point startPoint = proj.toScreenLocation(target);
startPoint.y = 0;
final LatLng startLatLng = proj.fromScreenLocation(startPoint);

final Interpolator interpolator = new LinearInterpolator();
handler.post(new Runnable() {
    @Override
    public void run() {
        long elapsed = SystemClock.uptimeMillis() - start;
        float t = interpolator.getInterpolation((float) elapsed / duration);
        double lng = t * target.longitude + (1 - t) * startLatLng.longitude;
        double lat = t * target.latitude + (1 - t) * startLatLng.latitude;
        marker.setPosition(new LatLng(lat, lng));
        if (t < 1.0) {
            // Post again 10ms later.
            handler.postDelayed(this, 10);
        } else {
            // animation ended
        }
    }
});

Answer 2

我将 MaciejGórski 的方法与这个 gist 中的代码结合起来。此外，添加了反弹效果。

public class MyBounceInterpolator implements android.view.animation.Interpolator {
    double mAmplitude = 1;
    double mFrequency = 10;

    public MyBounceInterpolator(double amplitude, double frequency) {
        mAmplitude = amplitude;
        mFrequency = frequency;
    }

    public float getInterpolation(float time) {
        double amplitude = mAmplitude;
        if (amplitude == 0) { amplitude = 0.05; }

        // The interpolation curve equation:
        //    -e^(-time / amplitude) * cos(frequency * time) + 1
        //
        // View the graph live: https://www.desmos.com/calculator/6gbvrm5i0s
        return (float) (-1 * Math.pow(Math.E, -time/ mAmplitude) * Math.cos(mFrequency * time) + 1);
    }
}

void dropMarker(final Marker marker, GoogleMap map) {
    final LatLng finalPosition = new LatLng(marker.getPosition().latitude, marker.getPosition().longitude);

    Projection projection = map.getProjection();
    Point startPoint = projection.toScreenLocation(finalPosition);
    startPoint.y = 0;
    final LatLng startLatLng = projection.fromScreenLocation(startPoint);
    final Interpolator interpolator = new MyBounceInterpolator(0.11, 4.6);

    TypeEvaluator<LatLng> typeEvaluator = new TypeEvaluator<LatLng>() {
        @Override
        public LatLng evaluate(float fraction, LatLng startValue, LatLng endValue) {
            float t = interpolator.getInterpolation(fraction);
            double lng = t * finalPosition.longitude + (1 - t) * startLatLng.longitude;
            double lat = t * finalPosition.latitude + (1 - t) * startLatLng.latitude;
            return new LatLng(lat, lng);
        }
    };

    Property<Marker, LatLng> property = Property.of(Marker.class, LatLng.class, "position");
    ObjectAnimator animator = ObjectAnimator.ofObject(marker, property, typeEvaluator, finalPosition);
    animator.setDuration(400);
    animator.start();
}