This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
The CanvasRenderingContext2D.shadowOffsetY property of the Canvas 2D API specifies the distance that shadows will be offset vertically.
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.
A float specifying the distance that shadows will be offset vertically. Positive values are down, and negative are up. The default value is 0 (no vertical offset). Infinity and NaN values are ignored.
This example adds a blurred shadow to a rectangle. The shadowColor property sets its color, shadowOffsetY sets its offset 25 units towards the bottom, and shadowBlur gives it a blur level of 10.
<canvas id="canvas"></canvas>
const canvas = document.getElementById("canvas");
const ctx = canvas.getContext("2d");
// Shadow
ctx.shadowColor = "red";
ctx.shadowOffsetY = 25;
ctx.shadowBlur = 10;
// Rectangle
ctx.fillStyle = "blue";
ctx.fillRect(20, 20, 150, 80);
| Specification |
|---|
| HTML> # dom-context-2d-shadowoffsety-dev> |
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Opera | Safari | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | WebView Android | WebView on iOS | |
shadowOffsetY |
1 | 12 | 1.5 | ≤12.1 | 2 | 18 | 4 | ≤12.1 | 1 | 1.0 | 4.4 | 1 |
CanvasRenderingContext2D
CanvasRenderingContext2D.shadowOffsetXCanvasRenderingContext2D.shadowColorCanvasRenderingContext2D.shadowBlur
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https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/shadowOffsetY