The clearRect() method of the Canvas 2D API which is used to erase the pixel in a rectangular area by setting the pixel color to transparent black (rgba(0, 0, 0, 0)).
Syntax:
abc.clearRect(x, y, width, height);
Parameters:
- x, y: These parameter represents the top-left coordinate of the rectangular box.
- width: It is used to set the width of the rectangular box
- height: It is used to set the of the rectangular box
Example 1: In the following example the clearRect() method is used to clear the pixel of a rectangle of size (200×300) from (50, 20).
html
<!DOCTYPE html><html lang="en">
<head>
<title>
How to clear the canvas
using clearRect in HTML?
</title>
</head>
<body>
<canvas id="canvas"></canvas>
<script>
const canvas = document.getElementById("canvas");
const abc = canvas.getContext('2d');
abc.beginPath();
abc.fillStyle = "red";
abc.fillRect(0, 0, 200, 300);
abc.clearRect(50, 20, 100, 100);
</script>
</body>
</html>
|
Output:
Example 2:
html
<!DOCTYPE html><html lang="en">
<head>
<title>
How to clear the canvas
using clearRect in HTML?
</title>
</head>
<body>
<canvas id="canvas"></canvas>
<script>
const canvas = document.getElementById("canvas");
const abc = canvas.getContext('2d');
// Draws a rectangle of 200x300
abc.beginPath();
abc.fillStyle = "red";
abc.fillRect(0, 0, 200, 300);
// Draws a triangle
abc.beginPath();
abc.fillStyle = "green";
abc.moveTo(10, 10);
abc.lineTo(150, 10);
abc.lineTo(120, 120);
abc.closePath();
abc.fill();
abc.clearRect(40, 25, 100, 70);
</script>
</body>
</html>
|
Output:
Example 3: In this example we will erase whole canvas.
html
<!DOCTYPE html><html lang="en">
<head>
<title>
How to clear the canvas
using clearRect in HTML?
</title>
</head>
<body>
<canvas id="canvas"></canvas>
<script>
const canvas = document.getElementById("canvas");
const abc = canvas.getContext('2d');
abc.beginPath();
abc.fillStyle = "red";
abc.fillRect(0, 0, 200, 300);
// This line will erase whole canvas and
// we will get an empty screen
abc.clearRect(0, 0, canvas.width, canvas.height);
</script>
</body>
</html>
|
Note: Be aware that clearRect() may cause unintended side effects if you’re not using paths properly. Make sure to call beginPath() before starting to draw new items after calling clearRect().
Reference: https://www.geeksforgeeks.org/html-canvas-clearrect-method/amp/