Android Google Map- how to divide map into 4 quadrants and know marker quadrant position

Question

i have a google map and i have some markers on . The markers are already rendered on the map and the markers are placed based on a certain category. These categories are quadrants on a map.

now after user clicks on a marker on the map i need to know which quadrant the marker was in.

here is what i have so far to . i thought i would get the 4 quadrants like this:

val screenLoc = googleMap.projection.toScreenLocation(marker.position)

val q1 = googleMap.projection.visibleRegion.farLeft
val q2 = googleMap.projection.visibleRegion.farRight
val q3 = googleMap.projection.visibleRegion.nearLeft
val q4 = googleMap.projection.visibleRegion.nearRight

but i am a little stuck how i would know which quadrant the marker is in this way.

Answer 1

Here is a working code snippet using the Javascript API. There is nothing in this code that you could not do with the Android API (sorry but I don't develop on Android). The logic would be exactly the same.

What I did (see comments in the code as well) is:

1. Get the map bounds and center point
2. Extract south-west and north-east coordinates
3. Create 4 rectangles based on these coords
4. Create a few markers
5. When a marker is clicked, check if it is within one of the 4 rectangles and output a message

Hope this helps.

Note: the rectangles could be transparent of course and if you need a visible division, you could set a stroke to the rectangles or divide the map with a Polyline.

var map;
var rectangles = [];

function initialize() {

  var center = new google.maps.LatLng(0, 0);

  var mapOptions = {
    zoom: 10,
    center: center,
    mapTypeId: google.maps.MapTypeId.ROADMAP
  };

  map = new google.maps.Map(document.getElementById("map-canvas"), mapOptions);

  // Set markers and rectangles once the map is idle
  google.maps.event.addListenerOnce(map, 'idle', function() {

    // Get map bounds, north-east and south-west coords
    var bounds = map.getBounds();
    var sw = bounds.getSouthWest();
    var ne = bounds.getNorthEast();

    // Create a few markers to test
    setMarker(new google.maps.LatLng(-0.05, -0.05));
    setMarker(new google.maps.LatLng(0.05, -0.05));
    setMarker(new google.maps.LatLng(0.05, 0.05));
    setMarker(new google.maps.LatLng(-0.05, 0.05));

    // Define 4 rectangles based on map bounds and center
    setRectangle(new google.maps.LatLngBounds(
      new google.maps.LatLng(center.lat(), sw.lng()),
      new google.maps.LatLng(ne.lat(), center.lng()),
    ), 'blue');

    setRectangle(new google.maps.LatLngBounds(
      new google.maps.LatLng(center.lat(), center.lng()),
      new google.maps.LatLng(ne.lat(), ne.lng()),
    ), 'yellow');

    setRectangle(new google.maps.LatLngBounds(
      new google.maps.LatLng(sw.lat(), sw.lng()),
      new google.maps.LatLng(center.lat(), center.lng()),
    ), 'green');

    setRectangle(new google.maps.LatLngBounds(
      new google.maps.LatLng(sw.lat(), center.lng()),
      new google.maps.LatLng(center.lat(), ne.lng()),
    ), 'red');
  });

}

function setMarker(latLng, title) {

  var marker = new google.maps.Marker({
    position: latLng,
    map: map,
    title: title,
    draggable: true
  });

  new google.maps.event.addListener(marker, 'click', function() {

    checkRectangleContains(this.position);
  });
}

function setRectangle(bounds, color) {

  var rectangle = new google.maps.Rectangle({
    strokeWeight: 0,
    fillColor: color,
    fillOpacity: 0.35,
    map: map,
    bounds: bounds,
    _reference: color
  });

  rectangles.push(rectangle);
}

function checkRectangleContains(markerCoords) {

  for (var i = 0; i < rectangles.length; i++) {

    // Check if the rectangle bounds contain the marker position
    if (rectangles[i].getBounds().contains(markerCoords)) {

      // Output message
      document.getElementById('rectangle-contains').innerHTML = 'This point is contained within ' + rectangles[i]._reference + ' rectangle.';
    }
  }
}

#map-canvas {
  height: 180px;
}

<div id="map-canvas"></div>
<div id="rectangle-contains"></div>
<!-- Replace the value of the key parameter with your own API key. -->
<script async defer src="//maps.googleapis.com/maps/api/js?key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk&callback=initialize">
</script>