CanvasRenderingContext2D.shadowBlur

The CanvasRenderingContext2D.shadowBlur property of the Canvas 2D API specifies the level of the blurring effect; this value doesn't correspond to a number of pixels and is not affected by the current transformation matrix. The default value is 0.

Syntax

ctx.shadowBlur = level;

level

A float specifying the level of the blurring effect. The default value is 0. Negative, Infinity or NaN values are ignored.

Examples

Using the shadowBlur property

This is just a simple code snippet using the shadowblur property to set a blurred shadow. Note that shadows are only drawn, if the shadowColor property is set to a non-transparent value, too.

HTML

<canvas id="canvas"></canvas>

JavaScript

var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');

ctx.shadowColor = 'black';
ctx.shadowBlur = 10;

ctx.fillStyle = 'white';
ctx.fillRect(10, 10, 100, 100);

Edit the code below and see your changes update live in the canvas:

Specifications

Specification	Status	Comment
WHATWG HTML Living Standard The definition of 'CanvasRenderingContext2D.shadowBlur' in that specification.	Living Standard

Browser compatibility

WebKit/Blink-specific notes

• In WebKit- and Blink-based browsers, a non-standard and deprecated method ctx.setShadow() is implemented besides this property.

  setShadow(width, height, blur, color, alpha);
  setShadow(width, height, blur, graylevel, alpha);
  setShadow(width, height, blur, r, g, b, a);
  setShadow(width, height, blur, c, m, y, k, a);
  

See also

• The interface defining it, CanvasRenderingContext2D.