More than 100 points and one polyline, Google Maps v3 - ruby-on-rails

Question

I'm working with google maps api v3 and I'm trying to use snap to road with more than 100 points but in addition end up with just one polyline with the whole route that I can put a small animation. The view is a html.erb.
var apiKey = any_key;
var map = handler.getMap();
var drawingManager;
var placeIdArray = [];
var snappedCoordinates = [];
var path = <%= raw(#locations) %>
var markers = <%= raw(#markers) %>
var centerOn = path[0].split(',');
function breadCrumbsGrapher(path) {
handler.removeMarkers(Gmaps.store.markers);
for(var i = 0; i < polylines.length; i++) {
polylines[i].setMap(null);
}
var divided = handlePath(path);
if (typeof divided[0] == 'object') {
for(var i = 0; i < divided.length; i++) {
runSnapToRoad(divided[i]);
}
} else {
runSnapToRoad(path);
}
}
function waypointsLimiter(path) {
var path_loc_size = path.length;
var limited = [];
if(path_loc_size > 30) {
var stepper = Math.ceil(path_loc_size/30);
for(var i = stepper; i < path_loc_size; i += stepper) {
limited.push(path[i]);
}
if(limited.indexOf(path[path_loc_size-1]) == -1) {
limited.push(path[path_loc_size-1]);
}
} else {
limited = path;
}
return limited;
}
function handlePath(path) {
var i = 0;
var j = path.length;
if (j > 100) {
var newArray = [],
chunk = j/2;
if (j >= 200) {
chunk = j/3;
} else if (j >= 300) {
chunk = j/4;
} else if (j >= 400) {
chunk = j/5;
} else if (j >= 500 ) {
chunk = j/6;
} else if (j >= 600) {
chunk = j/7;
} else if (j >= 700 || j <= 799) {
chunk = j/8;
} else {
alert('La ruta no puede ser mostrada');
}
for (i, j; i < j; i+=chunk) {
newArray.push(path.slice(i,i+chunk+1));
}
return newArray;
} else {
return path;
}
}
// Snap a user-created polyline to roads and draw the snapped path
function runSnapToRoad(path) {
var path = path.join('|');
$.get('https://roads.googleapis.com/v1/snapToRoads', {
interpolate: true,
key: apiKey,
path: path,
}, function(data) {
processSnapToRoadResponse(data);
drawSnappedPolyline();
});
}
// Store snapped polyline returned by the snap-to-road service.
function processSnapToRoadResponse(data) {
snappedCoordinates = [];
placeIdArray = [];
for (var i = 0; i < data.snappedPoints.length; i++) {
var latlng = new google.maps.LatLng(
data.snappedPoints[i].location.latitude,
data.snappedPoints[i].location.longitude);
snappedCoordinates.push(latlng);
placeIdArray.push(data.snappedPoints[i].placeId);
}
}
// Draws the snapped polyline (after processing snap-to-road response).
function drawSnappedPolyline() {
var symbol = {
path: google.maps.SymbolPath.FORWARD_CLOSED_ARROW,
scale: 3,
strokeColor: '#3B16B3'
};
var snappedPolyline = new google.maps.Polyline({
path: snappedCoordinates,
strokeColor: '#E51E25',
strokeWeight: 3,
icons: [{
icon: symbol,
offset: '0%'
}]
});
snappedPolyline.setMap(map);
animate(snappedPolyline);
zoomToObject(snappedPolyline);
polylines.push(snappedPolyline);
}
function zoomToObject(obj){
var bounds = new google.maps.LatLngBounds();
var points = obj.getPath().getArray();
for (var n = 0; n < points.length ; n++){
bounds.extend(points[n]);
}
map.fitBounds(bounds);
}
function animate(line) {
var count = 0;
window.setInterval(function() {
count = (count + 1) % 600;
var icons = line.get('icons');
icons[0].offset = (count / 6) + '%';
line.set('icons', icons);
}, 70);
}
breadCrumbsGrapher(path);
Also I've tried declaring a variable outside so I can concat all of the coordinates and generate a polyline with it but doesn't seem to work. Actualy that big array ends up being of 2000+ points.
The result that I have with the provided code
After all of that the issue is that I don't know how to merge the polylines to have just one line and being able to animate just that one line. If there's more than 100 coordinates I plot more polylines. In the image you can see that there's 3 icons (one for each polyline) and I need just to draw one line and have 1 icon.
To reproduce the issue just add a key and if you want use this set of coordinates:
https://drive.google.com/file/d/1jLb7Djv5DiSdR3k4QZRSatXBwrohlxcI/view?usp=sharing
function breadCrumbsGrapher(path) {
//mapMarkers();
snappedCoordinates = [];
handler.removeMarkers(Gmaps.store.markers);
for(var i = 0; i < polylines.length; i++) {
polylines[i].setMap(null);
}
var divided = handlePath(path);
if (typeof divided[0] == 'object') {
for(var i = 0; i < divided.length; i++) {
runSnapToRoad(divided[i]);
}
} else {
runSnapToRoad(path);
}
console.log(snappedCoordinates);
drawSnappedPolyline();
}
function runSnapToRoad(path) {
var path = path.join('|');
$.get('https://roads.googleapis.com/v1/snapToRoads', {
interpolate: true,
key: apiKey,
path: path,
}, function(data) {
processSnapToRoadResponse(data);
//drawSnappedPolyline();
});
}
I've changed the code but it doesn't work, even though I end up with a 2,557 coordinates array.
I've tried also tried this thinking that this could give me the time to have all coordinates:
async function breadCrumbsGrapher(path) {
//mapMarkers();
snappedCoordinates = [];
handler.removeMarkers(Gmaps.store.markers);
for(var i = 0; i < polylines.length; i++) {
polylines[i].setMap(null);
}
var divided = handlePath(path);
if (typeof divided[0] == 'object') {
for(var i = 0; i < divided.length; i++) {
await runSnapToRoad(divided[i]);
}
} else {
await runSnapToRoad(path);
}
console.log(snappedCoordinates);
drawSnappedPolyline();
}
and:
async function runSnapToRoad(path) {
var path = path.join('|');
await $.get('https://roads.googleapis.com/v1/snapToRoads', {
interpolate: true,
key: apiKey,
path: path,
}, function(data) {
processSnapToRoadResponse(data);
});
}
Thank you in advance.

Answer 1

You are using $.get() to query the Roads API which is an asynchronous call so when you call drawSnappedPolyline() from within your breadCrumbsGrapher function, you most probably don't (yet) have all coordinates in return from your AJAX call(s).
If you have 550 coordinates in your original path, you then know you must call the Roads API 6 times (5 times with 100 points + 1 time with 50 points). You should then be able to set a counter somewhere, to only draw your (complete) Polyline, once you got your 6 responses from the Roads API.
Or you could base that on the length of your final array (compared to the original path) although I don't know what would happen in case some points can't be "snapped".