CanvasRenderingContext2D.createLinearGradient() - Web APIs 编辑

The CanvasRenderingContext2D.createLinearGradient() method of the Canvas 2D API creates a gradient along the line connecting two given coordinates.

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

Note: Gradient coordinates are global, i.e., relative to the current coordinate space. When applied to a shape, the coordinates are NOT relative to the shape's coordinates.

Syntax

CanvasGradient ctx.createLinearGradient(x0, y0, x1, y1);

The createLinearGradient() method is specified by four parameters defining the start and end points of the gradient line.

Parameters

x0

The x-axis coordinate of the start point.

y0

The y-axis coordinate of the start point.

x1

The x-axis coordinate of the end point.

y1

The y-axis coordinate of the end point.

Return value

CanvasGradient

A linear CanvasGradient initialized with the specified line.

Examples

Filling a rectangle with a linear gradient

This example initializes a linear gradient using the createLinearGradient() method. Three color stops between the gradient's start and end points are then created. Finally, the gradient is assigned to the canvas context, and is rendered to a filled rectangle.

HTML

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

JavaScript

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

// Create a linear gradient
// The start gradient point is at x=20, y=0
// The end gradient point is at x=220, y=0
var gradient = ctx.createLinearGradient(20,0, 220,0);

// Add three color stops
gradient.addColorStop(0, 'green');
gradient.addColorStop(.5, 'cyan');
gradient.addColorStop(1, 'green');

// Set the fill style and draw a rectangle
ctx.fillStyle = gradient;
ctx.fillRect(20, 20, 200, 100);

Result

Specifications

Browser compatibility

BCD tables only load in the browser

Gecko-specific notes

• 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.

See also

• The interface defining this method: CanvasRenderingContext2D
• CanvasRenderingContext2D.createRadialGradient()