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CanvasRenderingContext2D.shadowBlur

The CanvasRenderingContext2D.shadowBlur property of the Canvas 2D API specifies the amount of blur applied to shadows. The default is 0 (no blur).

Syntax

ctx.shadowBlur = level;

level: A non-negative float specifying the level of shadow blur, where 0 represents no blur and larger numbers represent increasingly more blur. This value doesn't correspond to a number of pixels, and is not affected by the current transformation matrix. The default value is 0. Negative, Infinity, and NaN values are ignored.

Examples

Using the `shadowBlur` property

This example uses the shadowBlur property to add a blurred shadow to a rectangle. Note that shadows are only drawn if the shadowColor property is set to a non-transparent value, as well.

HTML

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

JavaScript

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

ctx.shadowColor = '#00f';
ctx.shadowBlur = 15;

ctx.fillStyle = '#fee';
ctx.fillRect(20, 20, 140, 100);

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

Specifications

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

Browser compatibilityUpdate compatibility data on GitHub

	Desktop
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari
Basic support	Yes	12	Yes	Yes	Yes	Yes

	Mobile
	Android webview	Chrome for Android	Edge Mobile	Firefox for Android	Opera for Android	iOS Safari	Samsung Internet
Basic support	Yes	Yes	Yes	Yes	Yes	Yes	Yes

WebKit/Blink-specific notes

In WebKit- and Blink-based browsers, the 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);