leaflet-virtual-grid

Leaflet Virtual Grid

You can use new VirtualGrid to generate simple, cacheable, grids of L.LatLngBounds objects you can use to query APIs. This lets you query APIs for smaller units and space and never make a call data in the same area twice.

Usage with Events

var vg = new VirtualGrid();

// listen for when new cells come into the view for the first time
vg.on("cellcreate", function(e){
  console.log(e.type, e);
});

// listen for when cells reenter the view
vg.on("cellenter", function(e){
  console.log(e.type, e);
});

// listen for when cells leave the view
vg.on("cellleave", function(e){
  console.log(e.type, e);
});

// add the grid to the map
vg.addTo(map);

Usage as a Class

var MyGrid = new VirtualGrid.extend({
  createCell: function(bounds, coords){
    console.log('create cell', bounds, coords);
  },

  cellEnter: function(bounds, coords){
    console.log('cell enter', bounds, coords);
  },

  cellLeave: function(bounds, coords){
    console.log('cell leave', bounds, coords);
  }
})

var thingWithGrid = new MyGrid().addTo(map);

Options

var vg = new VirtualGrid({
  cellSize: 512,
  updateInterval: 150
});

updateInterval

How often to update the grid. Defaults to 150

cellSize

How big each cell is in pixels. Defaults to 512

Example

Here is what the grid looks like under the hood...

Each rectangle would represent a call to an API or query to a data source. You would only make one request per cell so you not make repeat calls to areas like requesting all the data in a map view when a user performs a small pan.

Credit

Most of this code is based on L.Grid from https://github.com/Leaflet/Leaflet/commit/670dbaac045c7670ff26198136e440be9c2bb3e5.

Changelog

[1.0.7] 2018-07-04

Fixed

• trap for scenario in which map.getPixelWorldBounds() returns null.