Web/API/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 StandardThe definition of 'CanvasRenderingContext2D.quadraticCurveTo' in that specification. | Living Standard |
Browser compatibility
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Update compatibility data on GitHub
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
quadraticCurveTo
|
Chrome
Full support 1 |
Edge
Full support 12 |
Firefox
Full support 1.5 |
IE
Full support 9 |
Opera
Full support 11.6 |
Safari
Full support 3 |
WebView Android
Full support 1 |
Chrome Android
Full support 18 |
Firefox Android
Full support 4 |
Opera Android
Full support 12 |
Safari iOS
Full support 1 |
Samsung Internet Android
Full support 1.0 |
Legend
- Full support
- Full support
See also
- The interface defining this method:
CanvasRenderingContext2D
- Wikipedia article on Bézier curves
CanvasRenderingContext2D.quadraticCurveTo() by Mozilla Contributors is licensed under CC-BY-SA 2.5.