CanvasRenderingContext2D: bezierCurveTo() method
The
CanvasRenderingContext2D.bezierCurveTo()
method of the Canvas 2D API adds a cubic Bézier curve to the current
sub-path. It requires three points: the first two are control points and the third 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 Bézier curve.
Syntax
js
bezierCurveTo(cp1x, cp1y, cp2x, cp2y, x, y)
Parameters
cp1x
-
The x-axis coordinate of the first control point.
cp1y
-
The y-axis coordinate of the first control point.
cp2x
-
The x-axis coordinate of the second control point.
cp2y
-
The y-axis coordinate of the second control point.
x
-
The x-axis coordinate of the end point.
y
-
The y-axis coordinate of the end point.
Return value
None (undefined
).
Examples
How bezierCurveTo works
This example shows how a cubic Bézier curve is drawn.
HTML
html
<canvas id="canvas"></canvas>
JavaScript
js
// Define canvas and context
const canvas = document.getElementById("canvas");
const ctx = canvas.getContext("2d");
// Define the points as {x, y}
let start = { x: 50, y: 20 };
let cp1 = { x: 230, y: 30 };
let cp2 = { x: 150, y: 80 };
let end = { x: 250, y: 100 };
// Cubic Bézier curve
ctx.beginPath();
ctx.moveTo(start.x, start.y);
ctx.bezierCurveTo(cp1.x, cp1.y, cp2.x, cp2.y, end.x, end.y);
ctx.stroke();
// Start and end points
ctx.fillStyle = "blue";
ctx.beginPath();
ctx.arc(start.x, start.y, 5, 0, 2 * Math.PI); // Start point
ctx.arc(end.x, end.y, 5, 0, 2 * Math.PI); // End point
ctx.fill();
// Control points
ctx.fillStyle = "red";
ctx.beginPath();
ctx.arc(cp1.x, cp1.y, 5, 0, 2 * Math.PI); // Control point one
ctx.arc(cp2.x, cp2.y, 5, 0, 2 * Math.PI); // Control point two
ctx.fill();
Result
In this example, the control points are red and the start and end points are blue.
A simple Bézier curve
This example draws a simple Bézier curve using bezierCurveTo()
.
HTML
html
<canvas id="canvas"></canvas>
JavaScript
The curve begins at the point specified by moveTo()
: (30, 30). The first
control point is placed at (120, 160), and the second at (180, 10). The curve ends at
(220, 140).
js
const canvas = document.getElementById("canvas");
const ctx = canvas.getContext("2d");
ctx.beginPath();
ctx.moveTo(30, 30);
ctx.bezierCurveTo(120, 160, 180, 10, 220, 140);
ctx.stroke();
Result
Specifications
Specification |
---|
HTML Standard # dom-context-2d-beziercurveto-dev |
Browser compatibility
BCD tables only load in the browser
See also
- The interface defining this method:
CanvasRenderingContext2D
- Bézier curve