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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.


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


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.


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


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:


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

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidiOS SafariSamsung 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


Full support  
Full support

  • 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

Tag del documento e collaboratori

Hanno collaborato alla realizzazione di questa pagina: fscholz, nmve, erikadoyle
Ultima modifica di: fscholz,