android map （google map ,百度 ，高德 ）在路线 上画箭头

public void drawArrow(List<LatLng> list) {
LogUtils.show(TAG, "开始画箭头");
if (list == null || list.size() <= 1) {
LogUtils.show(TAG, "开始画箭头------失败");
return;
}
LogUtils.show(TAG, "开始画箭头------失满足条件");
for (int i = 1; i < list.size(); i++) {
double lat1 = list.get(i - 1).latitude;
double lng1 = list.get(i - 1).longitude;
double lat2 = list.get(i).latitude;
double lng2 = list.get(i).longitude;
double lat = (lat1 + lat2) / 2;
double lng = (lng1 + lng2) / 2;
LatLng modLat = new LatLng(lat, lng);
double brng = computeAzimuth(new LatLng(lat1, lng1), new LatLng(lat2, lng2));
MarkerOptions marker = new MarkerOptions().position(modLat);
marker.anchor(0.5f, 0.5f);
marker.icon(BitmapDescriptorFactory.fromResource(R.mipmap.line_arrow));
marker.rotation((float) brng);
marker.flat(true);
mMap.addMarker(marker);
LogUtils.show(TAG, "开始画箭头------箭头-- " + i + "角度为  " + brng);
}

}

// 计算方位角,正北向为0度，以顺时针方向递增
private double computeAzimuth(LatLng la1, LatLng la2) {
double lat1 = la1.latitude, lon1 = la1.longitude, lat2 = la2.latitude,
lon2 = la2.longitude;
double result = 0.0;

int ilat1 = (int) (0.50 + lat1 * 360000.0);
int ilat2 = (int) (0.50 + lat2 * 360000.0);
int ilon1 = (int) (0.50 + lon1 * 360000.0);
int ilon2 = (int) (0.50 + lon2 * 360000.0);

lat1 = Math.toRadians(lat1);
lon1 = Math.toRadians(lon1);
lat2 = Math.toRadians(lat2);
lon2 = Math.toRadians(lon2);

if ((ilat1 == ilat2) && (ilon1 == ilon2)) {
return result;
} else if (ilon1 == ilon2) {
if (ilat1 > ilat2)
result = 180.0;
} else {
double c = Math
.acos(Math.sin(lat2) * Math.sin(lat1) + Math.cos(lat2)
* Math.cos(lat1) * Math.cos((lon2 - lon1)));
double A = Math.asin(Math.cos(lat2) * Math.sin((lon2 - lon1))
/ Math.sin(c));
result = Math.toDegrees(A);
if ((ilat2 > ilat1) && (ilon2 > ilon1)) {
} else if ((ilat2 < ilat1) && (ilon2 < ilon1)) {
result = 180.0 - result;
} else if ((ilat2 < ilat1) && (ilon2 > ilon1)) {
result = 180.0 - result;
} else if ((ilat2 > ilat1) && (ilon2 < ilon1)) {
result += 360.0;
}
}
return result;
}