Geovisualization Developer's Guide

H.datalens. RasterLayer

Class Summary

Provides pixel-wise rendering of data.

[ For full details, see the Class Details ]

Class Description

Layer used when you need to visualize more then 10k points. The layer requires source data to be located in pixel coordinates. The rendering is implemented by drawing directly on a canvas. The layer is often used together with a Data Lens query which groups rows by pixels. This reduces the amount of data delivered to the client.

Constructor Details

H.datalens.RasterLayer ()

Property Details

static defaultDataToRows

Default value for dataToRows callback option. It represents each row as an object where property names correspond to data column names.

var layer = new H.datalens.RasterLayer(
   provider,
   {
     dataToRows: function(data) {
       return H.datalens.RasterLayer.defaultDataToRows(
         data
       ).filter(function() {
         ...
       })
     },
     ...
   }
);

Method Details

redraw ()

Force re-rendering of the layer. In the case where the callbacks passed to the layer options are not pure functions, you can call this method to force re-rendering.

static defaultRenderTile (points, canvas)

This is a default implementation of renderTile callback. This method represents each point as a black 1x1 pixel square.

Parameters:
points :: { Array.< H.datalens.RasterLayer.TilePoint > }
: Input data points within a tile
canvas :: { HTMLCanvasElement }
: The target canvas