我正试图在MapsV2中为polyline设置一个缓冲区用于android但是我还没有找到怎么做，我正在考虑在折线周围绘制一个多边形但是还没找到任何人已经做到了，有可能吗？
答案 0 :(得分：1)
您想在地图上绘制路径还是要在地图上绘制直线。
在这两种情况下，您都可以按照以下代码
PolylineOptions polyLineOptions = new PolylineOptions();
ArrayList<LatLng> points = new ArrayList<>();
//Code to populate Latlng
polyLineOptions.addAll(points);
polyLineOptions.width(mActivity.getResources().getDimensionPixelSize(R.dimen._2sdp));
polyLineOptions.color(ContextCompat.getColor(mContext, Color_Resource_id));
if (polyLineOptions != null) {
googleMap.addPolyline(polyLineOptions);
}
上面的代码是在地图上仅绘制直线。
现在，如果您想在地图上绘制完整路径，您可能需要使用google方向api https://maps.googleapis.com/maps/api/directions/
您可以使用以下类来解析相同的响应以获得总计latlngs
public class PathJSONParser {
public List<List<HashMap<String, String>>> parse(JSONObject jObject) {
List<List<HashMap<String, String>>> routes = new ArrayList<>();
JSONArray jRoutes;
JSONArray jLegs;
JSONArray jSteps;
try {
jRoutes = jObject.getJSONArray("routes");
/** Traversing all routes */
for (int i = 0; i < jRoutes.length(); i++) {
jLegs = ((JSONObject) jRoutes.get(i)).getJSONArray("legs");
List<HashMap<String, String>> path = new ArrayList<>();
/** Traversing all legs */
for (int j = 0; j < jLegs.length(); j++) {
jSteps = ((JSONObject) jLegs.get(j)).getJSONArray("steps");
/** Traversing all steps */
for (int k = 0; k < jSteps.length(); k++) {
String polyline;
polyline = (String) ((JSONObject) ((JSONObject) jSteps
.get(k)).get("polyline")).get("points");
List<LatLng> list = decodePoly(polyline);
/** Traversing all points */
for (int l = 0; l < list.size(); l++) {
HashMap<String, String> hm = new HashMap<>();
hm.put("lat",
Double.toString(( list.get(l)).latitude));
hm.put("lng",
Double.toString(( list.get(l)).longitude));
path.add(hm);
}
}
routes.add(path);
}
}
} catch (Exception e) {
e.printStackTrace();
}
return routes;
}
/**
* Method Courtesy :
* jeffreysambells.com/2010/05/27
* /decoding-polylines-from-google-maps-direction-api-with-java
* */
private List<LatLng> decodePoly(String encoded) {
List<LatLng> poly = new ArrayList<>();
int index = 0, len = encoded.length();
int lat = 0, lng = 0;
while (index < len) {
int b, shift = 0, result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lat += dlat;
shift = 0;
result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lng += dlng;
LatLng p = new LatLng((((double) lat / 1E5)),
(((double) lng / 1E5)));
poly.add(p);
}
return poly;
}
}
最后，您可以在课程中使用以下代码
private class ParserTask extends AsyncTask<String, Integer, List<List<HashMap<String, String>>>> {
@Override
protected List<List<HashMap<String, String>>> doInBackground(String... jsonData) {
JSONObject jObject;
List<List<HashMap<String, String>>> routes = new ArrayList<>();
try {
jObject = new JSONObject(jsonData[0]);
PathJSONParser parser = new PathJSONParser();
routes = parser.parse(jObject);
} catch (Exception e) {
e.printStackTrace();
}
return routes;
}
@Override
protected void onPostExecute(List<List<HashMap<String, String>>> routes) {
if (routes != null && routes.size() > 0) {
new DrawPoly().execute(routes);
}
}
}
private class DrawPoly extends AsyncTask<List<List<HashMap<String, String>>>,
PolylineOptions, PolylineOptions> {
@Override
protected PolylineOptions doInBackground(List<List<HashMap<String, String>>>... params) {
PolylineOptions polyLineOptions = new PolylineOptions();
ArrayList<LatLng> points;
if (params[0] != null && params[0].size() > 0) {
// traversing through routes
for (int j = 0; j < params[0].size(); j++) {
points = new ArrayList<>();
polyLineOptions = new PolylineOptions();
try {
List<HashMap<String, String>> path = params[0].get(j);
for (int k = 0; k < path.size(); k++) {
HashMap<String, String> point = path.get(k);
double lat = Double.parseDouble(point.get("lat"));
double lng = Double.parseDouble(point.get("lng"));
LatLng position = new LatLng(lat, lng);
points.add(position);
}
} catch (Exception e) {
e.printStackTrace();
}
polyLineOptions.addAll(points);
polyLineOptions.width(mActivity.getResources().getDimensionPixelSize(R.dimen.five));
polyLineOptions.color(ContextCompat.getColor(mContext, R.color.red));
}
}
return polyLineOptions;
}
@Override
protected void onPostExecute(PolylineOptions polyLineOptions) {
super.onPostExecute(polyLineOptions);
if (polyLineOptions != null) {
googleMap.addPolyline(polyLineOptions);
}
}
}
您需要确保将其放入asyncTask中。我希望它对你有用。
答案 1 :(得分：1)
在Google的directions api（https://maps.googleapis.com/maps/api/directions/json?origin=75+9th+Ave+New+York,+NY&destination=MetLife+Stadium+1+MetLife+Stadium+Dr+East+Rutherford,+NJ+07073&key=YOUR_API_KEY）中，您获得了一个 overview_polyline jsonObject， 从此处获取编码点，并使用此方法对其进行解码：
quit你得到纬度和经度列表， 现在，使用谷歌地图的 getMapAsync 方法在地图中添加此latlng：
false答案 2 :(得分：0)
执行此操作的最佳方法是使用方法mMap.animateCamera(CameraUpdateFactory.newLatLngBounds(yourBounds,200));。第二个参数（200）是yourBounds中定义的折线周围的填充。
以下是一些示例代码：
private GoogleMap mMap;
public void addPolyline(ArrayList<LatLng> result) {
// Paint Lines on map
PolylineOptions lineOptions = null;
lineOptions = new PolylineOptions();
lineOptions.addAll(result);
lineOptions.width(10);
lineOptions.color(Color.RED);
mMap.addPolyline(lineOptions);
LatLngBounds.Builder b = new LatLngBounds.Builder();
for (LatLng l: result) { b.include(l); }
mMap.animateCamera(CameraUpdateFactory.newLatLngBounds(b.build(),200));
}
答案 3 :(得分：0)
我找到了一种将折线添加到地图的方法。
从上面的链接你需要谷歌地图android util三个类。 MathUtil，PolyUtil和SpheriacalUtil。
我制作了一个功能并使用Retrofit连接到Google
public void drawMapPath (String origin, String destination, String travel){
RestInterface restInterface = ApiClient.getClient().create(RestInterface.class);
Call<GoogleDirections> call = restInterface.getDirections(origin, destination, travel, AppConfig.API_GOOGLEMAPS);
call.enqueue(new Callback<GoogleDirections>(){
@Override
public void onResponse(Call<GoogleDirections> call, Response<GoogleDirections> response){
if (response.isSuccessful()){
Routes[] route = response.body().getRoutes();
/** get bounds to set map after completion */
LatLngBounds.Builder mapBounds = new LatLngBounds.Builder();
LatLng northEast = new LatLng(Double.parseDouble(route[0].getBounds().getNortheast().getLat()),Double.parseDouble(route[0].getBounds().getNortheast().getLng()));
mapBounds.include(northEast);
LatLng southWest = new LatLng(Double.parseDouble(route[0].getBounds().getSouthwest().getLat()),Double.parseDouble(route[0].getBounds().getSouthwest().getLng()));
mapBounds.include(southWest);
/** no alternatives set so only one route*/
Legs[] leg = route[0].getLegs();
/** get the steps */
Steps[] step =leg[0].getSteps();
/** init points and options */
points = new ArrayList();
lineOptions = new PolylineOptions();
/** Traversing through the steps */
for (int i=0; i < step.length; i++ ){
String polyline;
polyline = step[i].getPolyline().getPoints();
/** classes needed from google */
List<LatLng> list = decodePoly(polyline);
/** Traversing all points in list*/
for (int n = 0; n < list.size(); n++) {
double lat = list.get(n).latitude;
double lon = list.get(n).longitude;
LatLng position=new LatLng(lat, lon);
points.add(position);
}
}
lineOptions.addAll(points);
lineOptions.width(12);
lineOptions.color(Color.BLUE);
lineOptions.geodesic(true);
googleMap.addPolyline(lineOptions);
googleMap.animateCamera(CameraUpdateFactory.newLatLngBounds(mapBounds.build(),10));
} else {
Toast.makeText(getActivity(), getString(R.string.server_broken), Toast.LENGTH_SHORT).show();
}
}
@Override
public void onFailure(Call<GoogleDirections> call, Throwable t) {
Log.d("Error ", t.getMessage());
}
});
}
private List<LatLng> decodePoly(String encoded) {
List<LatLng> poly = new ArrayList<>();
int index = 0, len = encoded.length();
int lat = 0, lng = 0;
while (index < len) {
int b, shift = 0, result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lat += dlat;
shift = 0;
result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lng += dlng;
LatLng p = new LatLng((((double) lat / 1E5)),
(((double) lng / 1E5)));
poly.add(p);
}
return poly;
}