Leaflet.fullcanvas

Provides implementation of points using canvas. With canvas you can show more number of points than SVG. The plugin uses the quad tree algorithm to minimize/optimize the number of points to be drawn.

Requires Leaflet 0.7.0 or newer.

Using the plugin

• For canvas with points: Demo
• For canvas with Loo..ots of points(160236 points): Demo
• For canvas with lines connecting points: Demo
• For canvas with points and popups: Demo

Usage

How to set data.

Create your map example:

 var map = L.map('map').setView([0, 35], 3);
     L.tileLayer('http://{s}.tile.cloudmade.com/7c2ed2e9170441289176d725eb0ca615/999/256/{z}/{x}/{y}.png', {
         maxZoom: 18
     }).addTo(map);

Create instance of the plugin canvas layer and add it to the map example:

    points = [];
    //make points slat denotes the latitude and slon denotes the longitude
    points.push({"slat": -33.3042, "slon": 26.5328});
    //make another point slat denotes the latitude and slon denotes the longitude
    points.push({"slat": -25, "slon": 29});
    //make a canvas layer
    var layer = new MyLayer();
    //set the data points to the layer
    layer.setData(points);
    //add canvas layer to the map
    layer.addLayerTo(map);

How to add data.

To add data live into the map: To the canvas layer created, you can add points

    //add points to the layer...here slat denotes the latitude and slon denotes the longitude
    layer.addData({"slat": -33.3042, "slon": 26.5328});

How to color/create your own points.

You can color/create your own points by overriding the drawSource function example:

    var MyLayer = L.FullCanvas.extend({
        //over riding the getsource function
        drawSource: function(point) {
            //get the context
            var ctx = layer.getCanvas().getContext("2d");
            ctx.globalCompositeOperation = "lighter";
            //drawing the shape of the point
            ctx.beginPath();
            //adding gradient 
            var grd = ctx.createRadialGradient(point.x, point.y, 0, point.x, point.y, 10);
            grd.addColorStop(0.200, 'rgba(255, 242, 0, 1)');
            grd.addColorStop(0.370, 'rgba(255, 157, 0, 1)');
            grd.addColorStop(0.5, 'rgba(255,255, 255, 1)');
            ctx.fillStyle = grd;
            ctx.arc(point.x, point.y , 2, 0, 2 * Math.PI, true);
            ctx.fill();
        }
    });

How to show popup.

You can color/create your own points by overriding the drawSource function example:

var MyLayer = L.FullCanvas.extend({
        //over riding the clickedPoints function
        clickedPoints: function(points){
            var text = "You clicked on the point Latitude["+ points[0].data.slat + "] Longitude["+ points[0].data.slon + "]";
            //show your popup
            alert(text);
        }

    });

how to draw lines between points.

Create instance of the plugin canvas layer and add points to the layer example:

    points = [];
    //make points slat denotes the source latitude and slon denotes the source longitude 
    //make points tlat denotes the target latitude and tlon denotes the target longitude 
    points.push({"slat": -33.3042, "slon": 26.5328,"tlat": -10, "tlon": 15});
    //make points slat denotes the source latitude and slon denotes the source longitude 
    //make points tlat denotes the target latitude and tlon denotes the target longitude 
    points.push({"slat": -25, "slon": 29, "tlat": -50, "tlon": 10});
    //make a canvas layer
    var layer = new MyLayer();
    //set the data points to the layer
    layer.setData(points);
    //add canvas layer to the map
    layer.addLayerTo(map);

how to draw lot of points in canvas.

We have to understand that when we have a lot of points to draw. We should not do

    var MyLayer = L.FullCanvas.extend({
        //over riding the getsource function
        drawSource: function(point) {
            //get the context
            var ctx = layer.getCanvas().getContext("2d");
            ctx.globalCompositeOperation = "lighter";
            //drawing the shape of the point
            ctx.beginPath();
            //adding gradient 
            var grd = ctx.createRadialGradient(point.x, point.y, 0, point.x, point.y, 10);
            grd.addColorStop(0.200, 'rgba(255, 242, 0, 1)');
            grd.addColorStop(0.370, 'rgba(255, 157, 0, 1)');
            grd.addColorStop(0.5, 'rgba(255,255, 255, 1)');
            ctx.fillStyle = grd;
            ctx.arc(point.x, point.y , 2, 0, 2 * Math.PI, true);
            ctx.fill();
        }
    });

Because if we have a 100000+ points the context drawing is expensive for each point. So best approach is to insert an image point instead of drawing the points.

    var imageObj = new Image();
    imageObj.src = "../data/shapes.png";//load any image
   //place the points in the canvas
    var MyLayer = L.FullCanvas.extend({
      drawSource: function(point) {
        var ctx = this.getCanvas().getContext("2d");
        ctx.drawImage(imageObj, point.x - 1, point.y - 1, 2, 2);
      }
    });