CanvasRenderingContext2D.quadraticCurveTo()

The CanvasRenderingContext2D.quadraticCurveTo() method of the Canvas 2D API adds a quadratic Bézier curve to the path. It requires two points. The first point is a control point and the second one is the end point. The starting point is the last 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 of the coordinate for the control point.
cpy
The y axis of the coordinate for the control point.
x
The x axis of the coordinate for the end point.
y
The y axis of the coordinate for the end point.

Examples

Using the quadraticCurveTo method

This is just a simple code snippet drawing a quadratic bezier curve. The control point is red and the start and end points are blue.

HTML

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

JavaScript

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

ctx.beginPath();
ctx.moveTo(50,20);
ctx.quadraticCurveTo(230, 30, 50, 100);
ctx.stroke();

ctx.fillStyle = 'blue';
// start point
ctx.fillRect(50, 20, 10, 10);
// end point
ctx.fillRect(50, 100, 10, 10);

ctx.fillStyle = 'red';
// control point
ctx.fillRect(230, 30, 10, 10);

Trying the quadraticCurveTo parameters

Edit the code below and see your changes update live in the canvas:

<canvas id="canvas" width="400" height="200" class="playable-canvas"></canvas>
<div class="playable-buttons">
  <input id="edit" type="button" value="Edit" />
  <input id="reset" type="button" value="Reset" />
</div>
<textarea id="code" class="playable-code">
ctx.beginPath();
ctx.moveTo(50,20);
ctx.quadraticCurveTo(230, 30, 50, 100);
ctx.stroke();</textarea>
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var textarea = document.getElementById("code");
var reset = document.getElementById("reset");
var edit = document.getElementById("edit");
var code = textarea.value;

function drawCanvas() {
  ctx.clearRect(0, 0, canvas.width, canvas.height);
  eval(textarea.value);
}

reset.addEventListener("click", function() {
  textarea.value = code;
  drawCanvas();
});

edit.addEventListener("click", function() {
  textarea.focus();
})

textarea.addEventListener("input", drawCanvas);
window.addEventListener("load", drawCanvas);

Specifications

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

Browser compatibility

(Yes)
Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) (Yes) (Yes) (Yes) (Yes)
(Yes)
Feature Android Chrome for Android Edge Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

See also

Document Tags and Contributors

 Contributors to this page: erikadoyle, fscholz
 Last updated by: erikadoyle,