Question

I am making a region drawing tool for a web application and I am using markers as anchors that the user can use to change the shape of a polygon.

This is what I have so far. http://demos.nodeline.com/leaflet_development/

the repo is at https://github.com/SpencerCooley/Leaflet_development

$(document).ready(function(){

var map, cloudmade, sanAntonio, polygonPoints  


 map = new L.Map('map');

 cloudmade = new L.TileLayer('http://{s}.tile.cloudmade.com/d4334cd6077140e3b92ccfae2b363070/997/256/{z}/{x}/{y}.png', {
    attribution: 'Map data &copy; <a href="http://openstreetmap.org">OpenStreetMap</a> contributors, <a href="http://creativecommons.org/licenses/by-sa/2.0/">CC-BY-SA</a>, Imagery © <a href="http://cloudmade.com">CloudMade</a>',
    maxZoom: 18
});


 sanAntonio = new L.LatLng(29.4238889, -98.4933333); // geographical point (longitude and latitude)


 map.setView(sanAntonio, 13).addLayer(cloudmade);




polygonPoints = [];

var polygon = new L.Polygon(polygonPoints);
map.addLayer(polygon);

map.on('click', function(e) {  


  var marker = new L.Marker(e.latlng, {draggable:true});
  polygonPoints.push(e.latlng);
  var markerId = polygonPoints.length -1 
  map.addLayer(marker);
  polygon.setLatLngs(polygonPoints);



  marker.on('drag', function(){
    var locationWhileDrag = marker.getLatLng();
    $('#first_marker').val(locationWhileDrag);
    polygonPoints.splice(markerId,1,locationWhileDrag);
    polygon.setLatLngs(polygonPoints);
  });      



});







});

I only want the markers to be normal size when the user is zoomed in to street level. When you zoom out the normal sized markers completely drown out the polygon. I looked through the docs but couldn’t find anything about this.

I am mainly looking for suggestions/brainstorming. I am thinking maybe there is a way to detect which zoom state you are currently in? If so, I could use an if statement to change the icon.

Answer 1

Ok so I found a few methods and came up with this:

//this sets up an icon to be replaced on redraw. 
var MyIcon = L.Icon.extend({
    iconUrl: 'marker.png',
    iconSize: new L.Point(10, 16),
    shadowSize: new L.Point(10, 16),
    iconAnchor: new L.Point(10, 16)
});

var icon = new MyIcon();

//When view resets use the smaller icon if zoom level is less than 13
map.on('viewreset', function(){
    if(map.getZoom() < 13){
        marker.setIcon(icon);
    }
});

The setIcon() method was not in the docs, I found it in a google forum and it worked.I made a smaller icon and I am basically just replacing the original icon when the zoom level is less than 13. I am going to implement different markers for different zoom levels now to give the markers ‘further away’ effect.

Here is the revised code.

$(document).ready(function(){

var map, cloudmade, sanAntonio, polygonPoints  

map = new L.Map('map');

cloudmade = new L.TileLayer('http://{s}.tile.cloudmade.com/d4334cd6077140e3b92ccfae2b363070/997/256/{z}/{x}/{y}.png', {
    attribution: 'Map data &copy; <a href="http://openstreetmap.org">OpenStreetMap</a> contributors, <a href="http://creativecommons.org/licenses/by-sa/2.0/">CC-BY-SA</a>, Imagery © <a href="http://cloudmade.com">CloudMade</a>',
    maxZoom: 18
});

sanAntonio = new L.LatLng(29.4238889, -98.4933333); // geographical point (longitude and latitude)

map.setView(sanAntonio, 13).addLayer(cloudmade);

polygonPoints = [];

var polygon = new L.Polygon(polygonPoints);
map.addLayer(polygon);

map.on('click', function(e) {  
    //this sets up an icon to be replaced when redraw. 
    var MyIcon = L.Icon.extend({
        iconUrl: 'marker.png',
        iconSize: new L.Point(10, 16),
        shadowSize: new L.Point(10, 16),
        iconAnchor: new L.Point(10, 16)
    });

    var icon = new MyIcon(); 
    //this sets up an icon to be replaced when redraw.

    var marker = new L.Marker(e.latlng, {draggable:true});
    polygonPoints.push(e.latlng);
    var markerId = polygonPoints.length -1 
    map.addLayer(marker);
    polygon.setLatLngs(polygonPoints);

    marker.on('drag', function(){
        var locationWhileDrag = marker.getLatLng();
        $('#first_marker').val(locationWhileDrag);
        polygonPoints.splice(markerId,1,locationWhileDrag);
        polygon.setLatLngs(polygonPoints);
    });      

    //When view resets use the small icon if zoom level is less than 13
    map.on('viewreset', function(){
        if(map.getZoom() < 13){
            marker.setIcon(icon);
        }
    });
});

});

here is the demo:
http://demos.nodeline.com/leaflet_development/