CanvasRenderingContext2D.quadraticCurveTo()

The CanvasRenderingContext2D.quadraticCurveTo() method of the Canvas 2D API adds a quadratic Bézier curve to the current sub-path. It requires two points: the first one is a control point and the second one is the end point. The starting point is the latest point in the current path, which can be changed using moveTo() before creating the quadratic Bézier curve.

Syntax

void ctx.quadraticCurveTo(cpx, cpy, x, y);

Parameters

cpx
The x-axis coordinate of the control point.
cpy
The y-axis coordinate of the control point.
x
The x-axis coordinate of the end point.
y
The y-axis coordinate of the end point.

Examples

How quadraticCurveTo works

This example shows how a quadratic Bézier curve is drawn.

HTML

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

JavaScript

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

// Quadratic Bézier curve
ctx.beginPath();
ctx.moveTo(50, 20);
ctx.quadraticCurveTo(230, 30, 50, 100);
ctx.stroke();

// Start and end points
ctx.fillStyle = 'blue';
ctx.beginPath();
ctx.arc(50, 20, 5, 0, 2 * Math.PI);   // Start point
ctx.arc(50, 100, 5, 0, 2 * Math.PI);  // End point
ctx.fill();

// Control point
ctx.fillStyle = 'red';
ctx.beginPath();
ctx.arc(230, 30, 5, 0, 2 * Math.PI);
ctx.fill();

Result

In this example, the control point is red and the start and end points are blue.

A simple quadratic curve

This example draws a simple quadratic Bézier curve using quadraticCurveTo().

HTML

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

JavaScript

The curve begins at the point specified by moveTo(): (20, 110). The control point is placed at (230, 150). The curve ends at (250, 20).

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

ctx.beginPath();
ctx.moveTo(20, 110);
ctx.quadraticCurveTo(230, 150, 250, 20);
ctx.stroke();

Result

Specifications

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

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
quadraticCurveToChrome Full support 1Edge Full support 12Firefox Full support 1.5IE Full support 9Opera Full support 11.6Safari Full support 3WebView Android Full support 1Chrome Android Full support 18Firefox Android Full support 4Opera Android Full support 12Safari iOS Full support 1Samsung Internet Android Full support 1.0

Legend

Full support  
Full support

See also