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).

Note: Shadows are only drawn if the shadowColor property is set to a non-transparent value. One of the shadowBlur, shadowOffsetX, or shadowOffsetY properties must be non-zero, as well.

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

Adding a shadow to a shape

This example adds a blurred shadow to a rectangle. The shadowColor property sets its color, and shadowBlur sets its level of bluriness.

HTML

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

JavaScript

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

// Shadow
ctx.shadowColor = 'red';
ctx.shadowBlur = 15;

// Rectangle
ctx.fillStyle = 'blue';
ctx.fillRect(20, 20, 150, 100);

Result

Specifications

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

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Basic supportChrome Full support YesEdge Full support 12Firefox Full support YesIE Full support YesOpera Full support YesSafari Full support YesWebView Android Full support YesChrome Android Full support YesEdge Mobile Full support YesFirefox Android Full support YesOpera Android Full support YesSafari iOS Full support YesSamsung Internet Android Full support Yes

Legend

Full support  
Full support

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);

See also

Document Tags and Contributors

Contributors to this page: mfluehr, fscholz, nmve, erikadoyle
Last updated by: mfluehr,