我试图用实时数据库的值改变谷歌地图中标记的位置
我尝试使用mMap.clear,但这不是正确的解决方案,因为如果我有100个标记并更改1个标记的位置,则100清除并重新定位make 1标记更改
myRef.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
mMap.clear();
for (DataSnapshot ds : dataSnapshot.getChildren()) {
Double lang = ds.child("lang").getValue(Double.class);
Double lat = ds.child("lat").getValue(Double.class);
save = new model(lat, lang);
ll = new LatLng(save.getLat(), save.getLang());
mCurrLocationMarker = mMap.addMarker(options
.position(ll));
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
我尝试更改标记的位置但实际结果添加了一个新的如果我不写mMap.clear并清除所有标记并添加它们以更改一个标记如果我写了mMap.clear
无需删除标记更新谷歌地图中的新位置()
1.初始创建的标记:
Double lang = ds.child("lang").getValue(Double.class);
Double lat = ds.child("lat").getValue(Double.class);
LatLng latLng=new latLng(lang ,lat )
// Creating a marker
Marker marker= mMap.addMarker(new MarkerOptions()
.position(latLng)
.draggable(true));
2.获得更新位置
LatLng oldLocation, newLocaation;
float bearing = (float) bearingBetweenLocations(oldLocation, newLocaation);
rotateMarker(marker, bearing);
private double bearingBetweenLocations(LatLng perviousPos,LatLng newPos) {
double PI = 3.14159;
double lat1 = perviousPos.latitude * PI / 180;
double long1 = perviousPos.longitude * PI / 180;
double lat2 = newPos.latitude * PI / 180;
double long2 = newPos.longitude * PI / 180;
double dLon = (long2 - long1);
double y = Math.sin(dLon) * Math.cos(lat2);
double x = Math.cos(lat1) * Math.sin(lat2) - Math.sin(lat1)
* Math.cos(lat2) * Math.cos(dLon);
double brng = Math.atan2(y, x);
brng = Math.toDegrees(brng);
brng = (brng + 360) % 360;
return brng;
}
.To rotate marker using above bearing angle i have used this code
Here isMarkerRotating is a boolean value. Add isMarkerRotating = false in OnCreate
method
private void rotateMarker(final Marker marker, final float toRotation) {
if(!isMarkerRotating) {
final Handler handler = new Handler();
final long start = SystemClock.uptimeMillis();
final float startRotation = marker.getRotation();
final long duration = 2000;
final Interpolator interpolator = new LinearInterpolator();
handler.post(new Runnable() {
@Override
public void run() {
isMarkerRotating = true;
long elapsed = SystemClock.uptimeMillis() - start;
float t = interpolator.getInterpolation((float) elapsed / duration);
float rot = t * toRotation + (1 - t) * startRotation;
float bearing = -rot > 180 ? rot / 2 : rot;
marker.setRotation(bearing);
if (t < 1.0) {
// Post again 16ms later.
handler.postDelayed(this, 16);
} else {
isMarkerRotating = false;
}
}
});
}
}
我建议在数组或Hashmap throw中存储标记,你可以随时更新它。
// code for ploat and store marker
HashMap<String, Marker> mPlotedMarker = new HashMap<>();
if (mMap != null) {
mMap.clear();
ArrayList<MarkerDataModel> mDataList = new ArrayList<>();
//With Hash map
for (int positon = 0; positon < mDataList.size(); positon++) {
LatLng markerPosition = new LatLng(mDataList.get(positon).getMarkerLat(), mDataList.get(positon).getMarkerLong());
Marker marker = mMap.addMarker(new MarkerOptions().position(markerPosition)
.title(mDataList.get(positon).getMarkerTitle()));
mPlotedMarker.put(mDataList.get(positon).getMarkerId(), marker);
}
}
//Now whenever you want to update
String markerId="1"; // replace which you want to update
if(mPlotedMarker.containsKey(markerId)){
Marker marker=mPlotedMarker.get(markerId);
if(marker!=null){
marker.setPosition(newPostion); //Specifie new position
}
}
您可以将标记对象存储为全局变量,只需在位置更改时更改选定的标记位置。
喜欢,
if (mCurrLocationMarker == null)
mCurrLocationMarker = mGoogleMap.addMarker(new MarkerOptions().icon(BitmapDescriptorFactory.fromResource(R.drawable.ic_pin_red)).position(location));
else
mCurrLocationMarker.setPosition(location);
由于您有多个标记,因此可以使用ArrayList或LinkedHashMap尝试相同的逻辑。
请检查此文件:https://filebin.net/m2vgvcms6g73kef2/TestFragment.java?t=e9g0tdki
希望能帮助到你.. :)