Module: ol/render

Methods

module:ol/render.toContext(context, opt_options){module:ol/render/canvas/Immediate~CanvasImmediateRenderer}

render.js, line 65

Binds a Canvas Immediate API to a canvas context, to allow drawing geometries to the context's canvas.

The units for geometry coordinates are css pixels relative to the top left corner of the canvas element.

import {toContext} from 'ol/render';
import Fill from 'ol/style/Fill';
import Polygon from 'ol/geom/Polygon';

var canvas = document.createElement('canvas');
var render = toContext(canvas.getContext('2d'),
    { size: [100, 100] });
render.setFillStrokeStyle(new Fill({ color: blue }));
render.drawPolygon(
    new Polygon([[[0, 0], [100, 100], [100, 0], [0, 0]]]));

Name	Type	Description
context	CanvasRenderingContext2D	Canvas context.
options	Options. Name Type Default Description size module:ol/size~Size Desired size of the canvas in css pixels. When provided, both canvas and css size will be set according to the pixelRatio. If not provided, the current canvas and css sizes will not be altered. pixelRatio number window.devicePixelRatio Pixel ratio (canvas pixel to css pixel ratio) for the canvas.

Returns:

Canvas Immediate.

Type Definitions

OrderFunction()

render.js, line 21

A function to be used when sorting features before rendering. It takes two instances of module:ol/Feature or module:ol/render/Feature and returns a {number}.

State{Object}

Properties:

Name	Type	Description
context	CanvasRenderingContext2D	Canvas context that the layer is being rendered to.
feature	module:ol/Feature~FeatureLike
geometry	module:ol/geom/SimpleGeometry~SimpleGeometry
pixelRatio	number	Pixel ratio used by the layer renderer.
resolution	number	Resolution that the render batch was created and optimized for. This is not the view's resolution that is being rendered.
rotation	number	Rotation of the rendered layer in radians.

ToContextOptions{Object}

Properties:

Name	Type	Argument	Default	Description
size	module:ol/size~Size	<optional>		Desired size of the canvas in css pixels. When provided, both canvas and css size will be set according to the pixelRatio. If not provided, the current canvas and css sizes will not be altered.
pixelRatio	number	<optional>	window.devicePixelRatio	Pixel ratio (canvas pixel to css pixel ratio) for the canvas.