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
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.
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