google maps API v3 - how to draw dynamic polygons/polylines?

Question

I have 4 days of experience with Google Maps Javascript API and i find their documentation and information sharing confusing at best.

Does anyone have experience or

Answer 1

After much research i came across this example. Which, after discovering it and googling it, seems the general answer to questions like mine. This is very basic but correct according to the V3 API.

Using the code in this example i am successfully building a prototype that i need. The code is basic but i have found that it can be extended to better fit my specifications, which is good.

The link provided in my comment to plexer's answer would be the best solution but the person developing it states that it is still under development and thus not stable enough for use in release applications.

Answer 2

Take a look at this example, from the Maps API v3 examples page:

http://code.google.com/apis/maps/documentation/javascript/examples/polyline-complex.html

The code listens to clicks on the map, and on each click adds an extra lat/lng pair into the array of a polyline. This results in a polyline which joins each clicked point.

Extending this to polygon should be relatively simple. At some point you will need to close the polygon. You could do this by listening to a click on the polygon or a marker (indicating an intersection) or by having a button the user can click, and setting the polygon to autoclose.

Answer 3

For Google Maps v3.7, you can use Drawing Library

Another good library: polygonEdit/polylineEdit by ryshkin@gmail.com

Answer 4

This looks to be the closest implementation to the polygon editor I've found: http://snipplr.com/view/38270/google-maps-api-v3--enableediting-polylines/

Answer 5

Take a look at my script for curved lines: http://curved_lines.overfx.net/

Here are the functions that I use:

function curved_line_generate(LatStart, LngStart, LatEnd, LngEnd, Color, Horizontal, Multiplier) {

  var LastLat = LatStart;
  var LastLng = LngStart;

  var PartLat;
  var PartLng;

  var Points = new Array(0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9);
  var PointsOffset = new Array(0.2, 0.35, 0.5, 0.55, 0.60, 0.55, 0.5, 0.35, 0.2);

  var OffsetMultiplier = 0;

  if (Horizontal == 1) {
    var OffsetLenght = (LngEnd - LngStart) * 0.1;
  } else {
    var OffsetLenght = (LatEnd - LatStart) * 0.1;
  }

  for (var i = 0; i < Points.length; i++) {
    if (i == 4) {
      OffsetMultiplier = 1.5 * Multiplier;
    }

    if (i >= 5) {
      OffsetMultiplier = (OffsetLenght * PointsOffset[i]) * Multiplier;
    } else {
      OffsetMultiplier = (OffsetLenght * PointsOffset[i]) * Multiplier;
    }

    if (Horizontal == 1) {
      PartLat = (LatStart + ((LatEnd - LatStart) * Points[i])) + OffsetMultiplier;
      PartLng = (LngStart + ((LngEnd - LngStart) * Points[i]));
    } else {
      PartLat = (LatStart + ((LatEnd - LatStart) * Points[i]));
      PartLng = (LngStart + ((LngEnd - LngStart) * Points[i])) + OffsetMultiplier;
    }

    curved_line_create_segment(LastLat, LastLng, PartLat, PartLng, Color);

    LastLat = PartLat;
    LastLng = PartLng;
  }

  curved_line_create_segment(LastLat, LastLng, LatEnd, LngEnd, Color);

}

function curved_line_create_segment(LatStart, LngStart, LatEnd, LngEnd, Color) {
  var LineCordinates = new Array();

  LineCordinates[0] = new google.maps.LatLng(LatStart, LngStart);
  LineCordinates[1] = new google.maps.LatLng(LatEnd, LngEnd);

  var Line = new google.maps.Polyline({
    path: LineCordinates,
    geodesic: false,
    strokeColor: Color,
    strokeOpacity: 1,
    strokeWeight: 3
  }); 

  Line.setMap(map);
}

Here is your html content + initializing script:

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<script type="text/javascript">

  var map;
  google.maps.event.addDomListener(window, 'load', initialize);

  function initialize() {

    /* Create Google Map */ 

    var myOptions = {
      zoom: 6,
      center: new google.maps.LatLng(41, 19.6),
      mapTypeId: google.maps.MapTypeId.ROADMAP
    };

    map = new google.maps.Map(document.getElementById('map_canvas'), myOptions);

    /* Add Sample Lines */

    /* Sofia - Burgas */
    curved_line_generate(42.68243562027229, 23.280029421875042, 42.488302202180364, 27.432861453125042,"#F00", true, 1);

    /* Sofia - Varna */
    curved_line_generate(42.68243562027229, 23.280029421875042, 43.19716750254011, 27.894287234375042,"#1a8809", true, 1);

    /* Ancona - Sofia */
    curved_line_generate(43.61221698671215, 13.458252078125042,42.68243562027229, 23.280029421875042, "#00F", true, 1);

    /* Sofia - Florence */
    curved_line_generate(42.68243562027229, 23.280029421875042, 43.73935229722859, 11.217041140625042,"#666", true, 1);

    /* Sofia - Athens */
    curved_line_generate(42.68243562027229, 23.280029421875042, 37.97884527841534, 23.719482546875042,"#ffa200", false, 2);
  }

</script>

Answer 6

I found this one quite easy.. You can draw polygons, can find their length and its quite easy.. http://geojason.info/demos/line-length-polygon-area-google-maps-v3/

here is a bit of code in case link goes down.

var map;

// Create a meausure object to store our markers, MVCArrays, lines and polygons
var measure = {
  mvcLine: new google.maps.MVCArray(),
  mvcPolygon: new google.maps.MVCArray(),
  mvcMarkers: new google.maps.MVCArray(),
  line: null,
  polygon: null
};

// When the document is ready, create the map and handle clicks on it
jQuery(document).ready(function() {

  map = new google.maps.Map(document.getElementById("map"), {
    zoom: 15,
    center: new google.maps.LatLng(39.57592, -105.01476),
    mapTypeId: google.maps.MapTypeId.ROADMAP,
    draggableCursor: "crosshair" // Make the map cursor a crosshair so the user thinks they should click something
  });

  google.maps.event.addListener(map, "click", function(evt) {
    // When the map is clicked, pass the LatLng obect to the measureAdd function
    measureAdd(evt.latLng);
  });

});

function measureAdd(latLng) {

  // Add a draggable marker to the map where the user clicked
  var marker = new google.maps.Marker({
      map: map,
      position: latLng,
      draggable: true,
      raiseOnDrag: false,
      title: "Drag me to change shape",
      icon: new google.maps.MarkerImage(
        "/images/demos/markers/measure-vertex.png", 
        new google.maps.Size(9, 9),
        new google.maps.Point(0, 0),
        new google.maps.Point(5, 5)
      )
  });

  // Add this LatLng to our line and polygon MVCArrays
  // Objects added to these MVCArrays automatically update the line and polygon shapes on the map
  measure.mvcLine.push(latLng);
  measure.mvcPolygon.push(latLng);

  // Push this marker to an MVCArray
  // This way later we can loop through the array and remove them when measuring is done
  measure.mvcMarkers.push(marker);

  // Get the index position of the LatLng we just pushed into the MVCArray
  // We'll need this later to update the MVCArray if the user moves the measure vertexes
  var latLngIndex = measure.mvcLine.getLength() - 1;

  // When the user mouses over the measure vertex markers, change shape and color to make it obvious they can be moved
  google.maps.event.addListener(marker, "mouseover", function() {
    marker.setIcon(
      new google.maps.MarkerImage("/images/demos/markers/measure-vertex-hover.png",
        new google.maps.Size(15, 15), 
        new google.maps.Point(0, 0), 
        new google.maps.Point(8, 8)
      )
    );
  });

  // Change back to the default marker when the user mouses out
  google.maps.event.addListener(marker, "mouseout", function() {
    marker.setIcon(
      new google.maps.MarkerImage(
        "/images/demos/markers/measure-vertex.png",
        new google.maps.Size(9, 9),
        new google.maps.Point(0, 0),
        new google.maps.Point(5, 5)
      )
    );
  });

  // When the measure vertex markers are dragged, update the geometry of the line and polygon by resetting the
  //     LatLng at this position
  google.maps.event.addListener(marker, "drag", function(evt) {
    measure.mvcLine.setAt(latLngIndex, evt.latLng);
    measure.mvcPolygon.setAt(latLngIndex, evt.latLng);
  });

  // When dragging has ended and there is more than one vertex, measure length, area.
  google.maps.event.addListener(marker, "dragend", function() {
    if (measure.mvcLine.getLength() > 1) {
      measureCalc();
    }
  });

  // If there is more than one vertex on the line
  if (measure.mvcLine.getLength() > 1) {

    // If the line hasn't been created yet
    if (!measure.line) {

      // Create the line (google.maps.Polyline)
      measure.line = new google.maps.Polyline({
        map: map,
        clickable: false,
        strokeColor: "#FF0000",
        strokeOpacity: 1,
        strokeWeight: 3,
        path:measure. mvcLine
      });

    }

    // If there is more than two vertexes for a polygon
    if (measure.mvcPolygon.getLength() > 2) {

      // If the polygon hasn't been created yet
      if (!measure.polygon) {

        // Create the polygon (google.maps.Polygon)
        measure.polygon = new google.maps.Polygon({
          clickable: false,
          map: map,
          fillOpacity: 0.25,
          strokeOpacity: 0,
          paths: measure.mvcPolygon
        });

      }

    }

  }

  // If there's more than one vertex, measure length, area.
  if (measure.mvcLine.getLength() > 1) {
      measureCalc();
  }
}