CanvasRenderingContext2D.createRadialGradient()

The CanvasRenderingContext2D.createRadialGradient() method of the Canvas 2D API creates a radial gradient using the size and coordinates of two circles.

This method returns a CanvasGradient. To be applied to a shape, the gradient must first be assigned to the fillStyle or strokeStyle properties.

createRadialGradient(x0, y0, r0, x1, y1, r1)

The createRadialGradient() method is specified by six parameters, three defining the gradient's start circle, and three defining the end circle.

x0

The x-axis coordinate of the start circle.

y0

The y-axis coordinate of the start circle.

r0

The radius of the start circle. Must be non-negative and finite.

x1

The x-axis coordinate of the end circle.

y1

The y-axis coordinate of the end circle.

r1

The radius of the end circle. Must be non-negative and finite.

CanvasGradient

A radial CanvasGradient initialized with the two specified circles.

This example initializes a radial gradient using the createRadialGradient() method. Three color stops between the gradient's two circles are then created. Finally, the gradient is assigned to the canvas context, and is rendered to a filled rectangle.

HTML

<canvas id="canvas" width="200" height="200"></canvas>

JavaScript

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

// Create a radial gradient
// The inner circle is at x=110, y=90, with radius=30
// The outer circle is at x=100, y=100, with radius=70
var gradient = ctx.createRadialGradient(110,90,30, 100,100,70);

// Add three color stops
gradient.addColorStop(0, 'pink');
gradient.addColorStop(.9, 'white');
gradient.addColorStop(1, 'green');

// Set the fill style and draw a rectangle
ctx.fillStyle = gradient;
ctx.fillRect(20, 20, 160, 160);

Result

• Starting with Gecko 2.0 (Firefox 4 / Thunderbird 3.3 / SeaMonkey 2.1), specifying non-finite values now throws NOT_SUPPORTED_ERR instead of SYNTAX_ERR.
• Starting with Gecko 5.0 (Firefox 5.0 / Thunderbird 5.0 / SeaMonkey 2.2), specifying a negative radius correctly throws INDEX_SIZE_ERR.

• The interface defining this method: CanvasRenderingContext2D
• CanvasRenderingContext2D.createLinearGradient()
• CanvasRenderingContext2D.createConicGradient()