JavaScript canvas2d object method: arc()
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The
arc() method of the JavaScript
DOM object returned
by the getContext("2d")
method applied to the HTML <canvas>
element creates a circular arc.
It
has the following syntax with the following parameters.
context.arc(x, y, r, startAngle, endAngle, counterclockwise)
|
Parameter
|
Required / Optional
|
Description
|
|
x
|
Required
|
x-coordinate or circle
centre
|
|
y
|
Required
|
y-coordinate or circle
centre
|
|
r
|
Required
|
Radius of circle
|
|
startAngle
|
Required
|
Start angle of arc in
radians from x-axis
|
|
endAngle
|
Required
|
End angle of arc in
radians from x-axis
|
|
counterclockwise
|
Optional
|
(default is false).
Boolean, if true then draw arc counterclockwise, otherwise clockwise
|
EXAMPLE:
HTML USED IN THIS EXAMPLE:
<!DOCTYPE html>
<html> <!-- Copyright (c) Nematrian Limited 2018 -->
<head></head>
<body>
<span id="element"></span>
<script>
var x2 = document.createElement("CANVAS");
x2.setAttribute("width", "200");
x2.setAttribute("height", "200");
x2.setAttribute("style", "border: 1px solid black");
var c2 = x2.getContext("2d");
c2.strokeStyle = "red";
c2.beginPath();
c2.arc(35, 45, 30, 0, 1.8 * Math.PI);
c2.stroke();
c2.scale(1.5, 1);
c2.strokeStyle = "blue";
c2.beginPath();
c2.arc(85, 45, 30, 0, 1.8 * Math.PI);
c2.stroke();
document.getElementById("element").appendChild(x2);
</script>
</body>
</html>
|
FUNCTION THAT MAY ASSIST IN TESTING WHETHER FEATURE IS SUPPORTED:
function isSupportedJavaScriptMethodCanvas2dArc() {
var x = document.createElement("CANVAS"); var c = x.getContext("2d"); return !!c.arc;
} |
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