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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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