JavaScript canvas2d object method: clearRect()
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The clearRect() method of the JavaScript
DOM object returned
by the getContext("2d")
method applied to the HTML <canvas>
element clears specified pixels within a rectangle.
It has the following
syntax with the following parameters.
context.clearRect(x, y, width, height)
Parameter
|
Required / Optional
|
Description
|
x
|
Required
|
x-coordinate of
upper-left corner
|
y
|
Required
|
y-coordinate of
upper-left corner
|
width
|
Required
|
Width of rectangle, in
pixels
|
height
|
Required
|
Height of rectangle, in
pixels
|
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", "100");
x2.setAttribute("style", "border: 1px solid black");
var c2 = x2.getContext("2d");
c2.fillStyle = "blue";
c2.fillRect(10, 10, 180, 80);
c2.clearRect(30, 40, 50, 20);
document.getElementById("element").appendChild(x2);
</script>
</body>
</html>
|
FUNCTION THAT MAY ASSIST IN TESTING WHETHER FEATURE IS SUPPORTED:
function isSupportedJavaScriptMethodCanvas2dClearRect() {
var x = document.createElement("CANVAS"); var c = x.getContext("2d"); return !!c.clearRect;
} |
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