light map

minimal, lightweight, self contained XYZ tile map viewer with a 2d canvas renderer.

live example

• an example with the most common methods let's you set the lat/lon/zoom, change the width/height of the canvas and monitor the load progress.
• a basic example of controls you should be able to drag the map around.
• an example of retina support first I thought it wasn't much but it seems to be a big deal. it's based on the devicePixelRatio, ideally you should use a @2x provider but I did an internal nearest neighbour resize.
• an example with a vignette as the map output is a Canvas2D, this shows how to post process the output.

more info

explanation and examples

basic example

<script src="light-map.min.js"></script>

<script>
    var provider = "http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png";
    var domains = "a,b,c".split( ',' );
    var map = new Map( provider, domains, 512,512,0,18 );
    document.body.appendChild( map.canvas );
    map.setView(0,0,1);
</script>

vignette example

<script src="light-map.min.js"></script>

<script>

    // provider: URL of the tile map service
    // domains: URL of the domains used by the tile map service
    // you can choose from a list of *free* TMS providers:
    // http://leaflet-extras.github.io/leaflet-providers/preview/
    // example:
    //
    //        provider = "http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png";
    //        domains = [ "a", "b", "c" ];
    //
    //alternately you can use .mbtiles

    var provider, domains;
    provider = "http://ttiles{s}.mqcdn.com/tiles/1.0.0/vy/sat/{z}/{x}/{y}.png";
    domains = [ "01" , "02", "03", "04" ];

    // you may need to use a proxy to load images on local servers
    // check out this gist : https://gist.github.com/nicoptere/a23ffae9ed51a5ca9766
    var proxy = "";//"./proxy.php?url=";

    var map = new Map( proxy + provider, domains, 512,512, 0, 10 );
    document.body.appendChild( map.canvas );

    //listening to the loading events
    function onLoadComplete( status ){

        if(status==0 )console.log( "onLoadComplete", "->", status );
    }
    //a new tile was loaded here
    function onTileLoaded( tile ){

        console.log( "onTileLoaded", "->", tile );
    }
    //the canvas' context is returned here
    function onTextureUpdate( ctx ){

        console.log( "onTextureUpdate" );
    }

    map.eventEmitter.on( Map.ON_LOAD_COMPLETE, onLoadComplete );
    map.eventEmitter.on( Map.ON_TILE_LOADED, onTileLoaded );
    map.eventEmitter.on( Map.ON_TEXTURE_UPDATE, onTextureUpdate );

    //this would be where I live :)
    var lat = o_lat = 48.854777;
    var lon = o_lon = 2.317499;
    var zoom = 16;
    map.setView( lat, lon, zoom );

    //it can be done in a loop
    function update(){

        var t = ( Math.sin( Date.now() * 0.001 ) );
        lat = o_lat;
        lon = o_lon + t * .0025;
        map.setView( lat, lon, zoom );
    }
    setInterval( update, 1000 / 60 );

    // as the result is a canvas, it's possible
    // to add post processing to map.ctx
    function vignette( ctx )
    {
        //create a gradient
        var w2 = map.width / 2;
        var grd = ctx.createRadialGradient( w2, w2, 0.000, w2, w2, w2);

        // Add colors
        grd.addColorStop(0.000, 'rgba(0, 0, 0, 0.00 )');
        grd.addColorStop(1.000, 'rgba(0, 0, 0, 0.75 )');

        // Fill with gradient
        ctx.fillStyle = grd;
        ctx.fillRect(0, 0, map.width, map.height );
    }
    map.eventEmitter.on( Map.ON_TEXTURE_UPDATE, vignette );


</script>

npm module installation

npm install light-map --save

related

Python library to perform Mercator conversions

Quad keys explained

npm globalMercator

License

This content is released under the MIT License.