Grouping markers by category to show and hide

Question

I am adding markers to a google map with the following:

    function addMarkersToMap(map) {
        // trigger resize on map in case canvas size is different         


        

Answer 1

Here is an example (ported from Mike Williams' v2 tutorial) that does that:

http://www.geocodezip.com/v3_MW_example_categories.html

code snippet:

// this variable will collect the html which will eventually be placed in the side_bar 
var side_bar_html = "";

var gmarkers = [];
var gicons = [];
var map = null;

var infowindow = new google.maps.InfoWindow({
  size: new google.maps.Size(150, 50)
});


gicons["red"] = new google.maps.MarkerImage("http://maps.google.com/mapfiles/ms/micons/red.png",
  // This marker is 32 pixels wide by 32 pixels tall.
  new google.maps.Size(32, 32),
  // The origin for this image is 0,0.
  new google.maps.Point(0, 0),
  // The anchor for this image is at 16,32.
  new google.maps.Point(16, 32));
// Marker sizes are expressed as a Size of X,Y
// where the origin of the image (0,0) is located
// in the top left of the image.

// Origins, anchor positions and coordinates of the marker
// increase in the X direction to the right and in
// the Y direction down.

var iconImage = new google.maps.MarkerImage('http://maps.google.com/mapfiles/ms/micons/red.png',
  // This marker is 32 pixels wide by 32 pixels tall.
  new google.maps.Size(32, 32),
  // The origin for this image is 0,0.
  new google.maps.Point(0, 0),
  // The anchor for this image is at 16,32.
  new google.maps.Point(16, 32));
// Shapes define the clickable region of the icon.
// The type defines an HTML <area> element 'poly' which
// traces out a polygon as a series of X,Y points. The final
// coordinate closes the poly by connecting to the first
// coordinate.
var iconShape = {
  coord: [9, 0, 6, 1, 4, 2, 2, 4, 0, 8, 0, 12, 1, 14, 2, 16, 5, 19, 7, 23, 8, 26, 9, 30, 9, 34, 11, 34, 11, 30, 12, 26, 13, 24, 14, 21, 16, 18, 18, 16, 20, 12, 20, 8, 18, 4, 16, 2, 15, 1, 13, 0],
  type: 'poly'
};

function getMarkerImage(iconColor) {
  if ((typeof(iconColor) == "undefined") || (iconColor == null)) {
    iconColor = "red";
  }
  if (!gicons[iconColor]) {
    gicons[iconColor] = new google.maps.MarkerImage("http://maps.google.com/mapfiles/ms/micons/" + iconColor + ".png",
      // This marker is 20 pixels wide by 34 pixels tall.
      new google.maps.Size(32, 32),
      // The origin for this image is 0,0.
      new google.maps.Point(0, 0),
      // The anchor for this image is at 6,20.
      new google.maps.Point(16, 32));
  }
  return gicons[iconColor];

}

function category2color(category) {
  var color = "red";
  switch (category) {
    case "theatre":
      color = "blue";
      break;
    case "golf":
      color = "green";
      break;
    case "info":
      color = "yellow";
      break;
    default:
      color = "red";
      break;
  }
  return color;
}

gicons["theatre"] = getMarkerImage(category2color("theatre"));
gicons["golf"] = getMarkerImage(category2color("golf"));
gicons["info"] = getMarkerImage(category2color("info"));

// A function to create the marker and set up the event window
function createMarker(latlng, name, html, category) {
  var contentString = html;
  var marker = new google.maps.Marker({
    position: latlng,
    icon: gicons[category],
    map: map,
    title: name,
    zIndex: Math.round(latlng.lat() * -100000) << 5
  });
  // === Store the category and name info as a marker properties ===
  marker.mycategory = category;
  marker.myname = name;
  gmarkers.push(marker);

  google.maps.event.addListener(marker, 'click', function() {
    infowindow.setContent(contentString);
    infowindow.open(map, marker);
  });
}

// == shows all markers of a particular category, and ensures the checkbox is checked ==
function show(category) {
  for (var i = 0; i < gmarkers.length; i++) {
    if (gmarkers[i].mycategory == category) {
      gmarkers[i].setVisible(true);
    }
  }
  // == check the checkbox ==
  document.getElementById(category + "box").checked = true;
}

// == hides all markers of a particular category, and ensures the checkbox is cleared ==
function hide(category) {
  for (var i = 0; i < gmarkers.length; i++) {
    if (gmarkers[i].mycategory == category) {
      gmarkers[i].setVisible(false);
    }
  }
  // == clear the checkbox ==
  document.getElementById(category + "box").checked = false;
  // == close the info window, in case its open on a marker that we just hid
  infowindow.close();
}

// == a checkbox has been clicked ==
function boxclick(box, category) {
  if (box.checked) {
    show(category);
  } else {
    hide(category);
  }
  // == rebuild the side bar
  makeSidebar();
}

function myclick(i) {
  google.maps.event.trigger(gmarkers[i], "click");
}


// == rebuilds the sidebar to match the markers currently displayed ==
function makeSidebar() {
  var html = "";
  for (var i = 0; i < gmarkers.length; i++) {
    if (gmarkers[i].getVisible()) {
      html += '' + gmarkers[i].myname + '<\/a>
';
    }
  }
  document.getElementById("side_bar").innerHTML = html;
}

function initialize() {
  var myOptions = {
    zoom: 11,
    center: new google.maps.LatLng(53.8363, -3.0377),
    mapTypeId: google.maps.MapTypeId.ROADMAP
  }
  map = new google.maps.Map(document.getElementById("map"), myOptions);


  google.maps.event.addListener(map, 'click', function() {
    infowindow.close();
  });



  // Read the data
  // downloadUrl("categories.xml", function(doc) {
  var xml = xmlParse(xmlData);
  var markers = xml.documentElement.getElementsByTagName("marker");

  for (var i = 0; i < markers.length; i++) {
    // obtain the attribues of each marker
    var lat = parseFloat(markers[i].getAttribute("lat"));
    var lng = parseFloat(markers[i].getAttribute("lng"));
    var point = new google.maps.LatLng(lat, lng);
    var address = markers[i].getAttribute("address");
    var name = markers[i].getAttribute("name");
    var html = "" + name + "<\/b>
" + address;
    var category = markers[i].getAttribute("category");
    // create the marker
    var marker = createMarker(point, name, html, category);
  }

  // == show or hide the categories initially ==
  show("theatre");
  hide("golf");
  hide("info");
  // == create the initial sidebar ==
  makeSidebar();
  // });
}
google.maps.event.addDomListener(window, 'load', initialize);

var xmlData = '                  ';


function xmlParse(str) {
  if (typeof ActiveXObject != 'undefined' && typeof GetObject != 'undefined') {
    var doc = new ActiveXObject('Microsoft.XMLDOM');
    doc.loadXML(str);
    return doc;
  }

  if (typeof DOMParser != 'undefined') {
    return (new DOMParser()).parseFromString(str, 'text/xml');
  }

  return createElement('div', null);
}

html,
body {
  height: 100%;
}

  Theatres:
     Golf Courses:
     Tourist Information: