如何使用谷歌地图沿折线移动标记

Question

我正在尝试根据折线和动画移动标记.与下图类似:

Mapbox已经开始提供这种演示了.但我希望使用谷歌地图实现同样的目标.但是现在我的标记不是沿着路径旋转.这是我尝试过的:

private void onReady(List<LatLng> polyz) {

      for (int i = 0; i < polyz.size() - 1; i++) {
        LatLng src = polyz.get(i);
        LatLng dest = polyz.get(i + 1);
        Polyline line = map.addPolyline(new PolylineOptions()
            .add(new LatLng(src.latitude, src.longitude),
                new LatLng(dest.latitude, dest.longitude))
            .width(2).color(Color.RED).geodesic(true));

      }
      LatLngBounds.Builder builder = new LatLngBounds.Builder();
      builder.include(polyz.get(0));
      builder.include(polyz.get(polyz.size()-1));
      map.moveCamera(CameraUpdateFactory.newLatLngBounds(builder.build(), 48));
      map.animateCamera(CameraUpdateFactory.zoomTo(7), 1000, null);
      BitmapDescriptor icon = BitmapDescriptorFactory.fromResource(R.drawable.car);
      marker = map.addMarker(new MarkerOptions()
          .position(polyz.get(0))
          .title("Curr")
          .snippet("Move"));
      marker.setIcon(icon);

    }

和动画:

    private void animateMarker(GoogleMap myMap, final Marker marker, final List<LatLng> directionPoint,
      final boolean hideMarker) {
    final Handler handler = new Handler();
    final long start = SystemClock.uptimeMillis();
    Projection proj = myMap.getProjection();
    final long duration = 600000;

    final Interpolator interpolator = new LinearInterpolator();

    handler.post(new Runnable() {
      int i = 0;

      @Override
      public void run() {
        long elapsed = SystemClock.uptimeMillis() - start;
        float t = interpolator.getInterpolation((float) elapsed
            / duration);
        Location location=new Location(String.valueOf(directionPoint.get(i)));
        Location newlocation=new Location(String.valueOf(directionPoint.get(i+1)));
        marker.setAnchor(0.5f, 0.5f);
        marker.setRotation(location.bearingTo(newlocation)  - 45);
        if (i < directionPoint.size()) {
          marker.setPosition(directionPoint.get(i));
        }
        i++;

        if (t < 1.0) {
          // Post again 16ms later.
          handler.postDelayed(this, 16);
        } else {
          if (hideMarker) {
            marker.setVisible(false);
          } else {
            marker.setVisible(true);
          }
        }
      }
    });
  }

Answer 1

您可以根据自定义标记动画为您的任务使用您的方法:在所有方向点分别为汽车运动和汽车转弯设置动画.为此您需要2种动画:

1)汽车运动动画;

2)车转动画;

它在结束时相互呼叫(汽车运动动画结束时调用汽车转动动画,反之亦然:汽车转动动画结束时调用汽车运动动画,因此对于汽车路径的所有点).

例如图:

1)动画从轿厢移动P0到P1;

2)汽车开启动画P1;

3)动画汽车从运动P1到P2

等等.

汽车运动动画可以通过以下方法实现:

private void animateCarMove(final Marker marker, final LatLng beginLatLng, final LatLng endLatLng, final long duration) {
        final Handler handler = new Handler();
        final long startTime = SystemClock.uptimeMillis();

        final Interpolator interpolator = new LinearInterpolator();

        // set car bearing for current part of path
        float angleDeg = (float)(180 * getAngle(beginLatLng, endLatLng) / Math.PI);
        Matrix matrix = new Matrix();
        matrix.postRotate(angleDeg);
        marker.setIcon(BitmapDescriptorFactory.fromBitmap(Bitmap.createBitmap(mMarkerIcon, 0, 0, mMarkerIcon.getWidth(), mMarkerIcon.getHeight(), matrix, true)));

        handler.post(new Runnable() {
            @Override
            public void run() {
                // calculate phase of animation
                long elapsed = SystemClock.uptimeMillis() - startTime;
                float t = interpolator.getInterpolation((float) elapsed / duration);
                // calculate new position for marker
                double lat = (endLatLng.latitude - beginLatLng.latitude) * t + beginLatLng.latitude;
                double lngDelta = endLatLng.longitude - beginLatLng.longitude;

                if (Math.abs(lngDelta) > 180) {
                    lngDelta -= Math.signum(lngDelta) * 360;
                }
                double lng = lngDelta * t + beginLatLng.longitude;

                marker.setPosition(new LatLng(lat, lng));

                // if not end of line segment of path 
                if (t < 1.0) {
                    // call next marker position
                    handler.postDelayed(this, 16);
                } else {
                    // call turn animation
                    nextTurnAnimation();
                }
            }
        });
    }

哪里

mMarkerIcon 是:

Bitmap mMarkerIcon;
...
mMarkerIcon = BitmapFactory.decodeResource(getResources(), R.drawable.the_car);  // for your car icon in file the_car.png in drawable folder

和汽车图标应该是朝北的:

适用于正确的旋转

nextTurnAnimation() - 在汽车运动动画结束时调用方法启动汽车转动动画:

private void nextTurnAnimation() {
        mIndexCurrentPoint++;

        if (mIndexCurrentPoint < mPathPolygonPoints.size() - 1) {
            LatLng prevLatLng = mPathPolygonPoints.get(mIndexCurrentPoint - 1);
            LatLng currLatLng = mPathPolygonPoints.get(mIndexCurrentPoint);
            LatLng nextLatLng = mPathPolygonPoints.get(mIndexCurrentPoint + 1);

            float beginAngle = (float)(180 * getAngle(prevLatLng, currLatLng) / Math.PI);
            float endAngle = (float)(180 * getAngle(currLatLng, nextLatLng) / Math.PI);

            animateCarTurn(mCarMarker, beginAngle, endAngle, TURN_ANIMATION_DURATION);
        }
    }

反过来车转动画方法可以是这样的:

private void animateCarTurn(final Marker marker, final float startAngle, final float endAngle, final long duration) {
        final Handler handler = new Handler();
        final long startTime = SystemClock.uptimeMillis();
        final Interpolator interpolator = new LinearInterpolator();

        final float dAndgle = endAngle - startAngle;

        Matrix matrix = new Matrix();
        matrix.postRotate(startAngle);
        Bitmap rotatedBitmap = Bitmap.createBitmap(mMarkerIcon, 0, 0, mMarkerIcon.getWidth(), mMarkerIcon.getHeight(), matrix, true);
        marker.setIcon(BitmapDescriptorFactory.fromBitmap(rotatedBitmap));

        handler.post(new Runnable() {
            @Override
            public void run() {

                long elapsed = SystemClock.uptimeMillis() - startTime;
                float t = interpolator.getInterpolation((float) elapsed / duration);

                Matrix m = new Matrix();
                m.postRotate(startAngle + dAndgle * t);
                marker.setIcon(BitmapDescriptorFactory.fromBitmap(Bitmap.createBitmap(mMarkerIcon, 0, 0, mMarkerIcon.getWidth(), mMarkerIcon.getHeight(), m, true)));

                if (t < 1.0) {
                    handler.postDelayed(this, 16);
                } else {
                    nextMoveAnimation();
                }
            }
        });
    }

在哪里nextMoveAnimation():

private void nextMoveAnimation() {
        if (mIndexCurrentPoint <  mPathPolygonPoints.size() - 1) {
            animateCarMove(mCarMarker, mPathPolygonPoints.get(mIndexCurrentPoint), mPathPolygonPoints.get(mIndexCurrentPoint+1), MOVE_ANIMATION_DURATION);
        }
    }

该mPathPolygonPoints(开车出行的geopoints)是:

private List<LatLng> mPathPolygonPoints;

并且mIndexCurrentPoint变量是路径上当前点的索引(在动画开始时它应该是0并且在nextTurnAnimation()方法的每个路径上增加).

TURN_ANIMATION_DURATION - 汽车开启路径geopoint的持续时间(毫秒)动画;

MOVE_ANIMATION_DURATION - 汽车沿路径线段移动的持续时间(毫秒);

获得方位你可以使用这样的方法:

private double getAngle(LatLng beginLatLng, LatLng endLatLng) {
        double f1 = Math.PI * beginLatLng.latitude / 180;
        double f2 = Math.PI * endLatLng.latitude / 180;
        double dl = Math.PI * (endLatLng.longitude - beginLatLng.longitude) / 180;
        return Math.atan2(Math.sin(dl) * Math.cos(f2) , Math.cos(f1) * Math.sin(f2) - Math.sin(f1) * Math.cos(f2) * Math.cos(dl));;
    }

最后,您可以通过调用animateCarMove()一次启动所有动画:

animateCarMove(mCarMarker, mPathPolygonPoints.get(0), mPathPolygonPoints.get(1), MOVE_ANIMATION_DURATION);

对于汽车路径的每个点,将自动调用其他动画步骤.

你应该考虑一些"特殊情况",如:

1)改变转角的符号(例如轴承从-120度变化到150度);

2)用户中断动画的可能性;

3)计算路径段长度上的动画持续时间(例如,1 km的段长度而不是固定的1秒MOVE_ANIMATION_DURATION)

4)可能调整价值16以handler.postDelayed(this, 16);获得更好的表现;

5)等等.

Answer 2

我认为您正在寻找的是Marker Animations。

您可以为标记设置动画，以便它们在各种不同的情况下表现出动态运动。要指定标记的动画方式，请使用标记的动画属性（类型为 google.maps.Animation）。支持以下动画值：

-DROP 表示标记首次放置在地图上时应从地图顶部掉落到其最终位置。一旦标记停止，动画就会停止，动画将恢复为空。这种类型的动画通常在创建标记期间指定。

-BOUNCE 表示标记应弹回原位。弹跳标记将继续弹跳，直到其动画属性显式设置为 null。

以下是该指南的摘录：

var marker;

      function initMap() {
        var map = new google.maps.Map(document.getElementById('map'), {
          zoom: 13,
          center: {lat: 59.325, lng: 18.070}
        });

        marker = new google.maps.Marker({
          map: map,
          draggable: true,
          animation: google.maps.Animation.DROP,
          position: {lat: 59.327, lng: 18.067}
        });
        marker.addListener('click', toggleBounce);
      }

      function toggleBounce() {
        if (marker.getAnimation() !== null) {
          marker.setAnimation(null);
        } else {
          marker.setAnimation(google.maps.Animation.BOUNCE);
        }
      }