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

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();
  }
}