Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
-
Economics & Finance
Selected Reading
How to draw an oval in HTML5 canvas?
Drawing an oval in HTML5 canvas can be achieved by scaling a circle. Since canvas doesn't have a built-in oval method, we use the scale() transformation to stretch a circle into an elliptical shape.
How It Works
The technique involves three steps:
- Save the current canvas state with
save() - Apply scaling transformation to stretch the circle
- Draw a circle using
arc(), which appears as an oval due to scaling - Restore the original state with
restore()
Example
<!DOCTYPE HTML>
<html>
<head>
<title>HTML5 Canvas Oval</title>
</head>
<body>
<canvas id="newCanvas" width="450" height="300" style="border: 1px solid #ccc;"></canvas>
<script>
// Get canvas and context
var canvas = document.getElementById('newCanvas');
var context = canvas.getContext('2d');
// Oval parameters
var centerX = 0;
var centerY = 0;
var radius = 40;
// Save current state
context.save();
// Move to center of canvas
context.translate(canvas.width / 2, canvas.height / 2);
// Scale horizontally by 2, vertically by 1 (creates oval)
context.scale(2, 1);
// Draw circle (will appear as oval due to scaling)
context.beginPath();
context.arc(centerX, centerY, radius, 0, 2 * Math.PI, false);
// Restore original state before styling
context.restore();
// Apply fill and stroke
context.fillStyle = '#000000';
context.fill();
context.lineWidth = 2;
context.strokeStyle = 'yellow';
context.stroke();
</script>
</body>
</html>
Output
Key Parameters
- scale(2, 1): Stretches horizontally by factor of 2, keeps vertical scale at 1
- translate(): Positions the oval at canvas center
- save()/restore(): Preserves canvas state to prevent scaling from affecting stroke width
Alternative Scaling
You can create different oval shapes by adjusting the scale values:
// Tall oval (vertical stretch) context.scale(1, 2); // Wide oval (horizontal stretch) context.scale(3, 1); // Slightly stretched oval context.scale(1.5, 0.8);
Conclusion
HTML5 canvas ovals are created by scaling circles using the scale() transformation. Always use save() and restore() to isolate the scaling transformation and maintain proper stroke appearance.
Updated on: 2026-03-15T23:18:59+05:30
1K+ Views
Advertisements