Fabric.js | Ellipse lockUniScaling Property

Last Updated : 19 Jun, 2020

In this article, we are going to see how to lock non-uniform scaling of a canvas ellipse using FabricJS so that the aspect ratio of the object is maintained. The canvas means ellipse is movable and can be stretched according to requirement. Further, the ellipse can be customized when it comes to initial stroke color, fill color, stroke width, or radius.

To make it possible we are going to use a JavaScript library called FabricJS. After importing the library using CDN, we will create a canvas block in the body tag which will contain our ellipse. After this, we will initialize instances of Canvas and Ellipse provided by FabricJS and lock the non-uniform scaling of the canvas ellipse using lockUniScaling property and render the Ellipse on the Canvas as given in the example below.

Syntax:

fabric.Ellipse({
    rx: number,
    ry: number,
    lockUniScaling: boolean
});

Parameters: This function accept three parameters as mentioned above and described below:

rx: This parameter defines the horizontal radius.
ry: This parameter defines the vertical radius.
lockUniScaling: This parameter defines whether to lock non-uniform scaling or not.

Example: This example uses FabricJS to lock non-uniform scaling of a canvas ellipse.

<!DOCTYPE html> 
<html> 
  
<head> 
    <title>  
        Lock non-uniform scaling of a canvas  
        ellipse using FabricJS 
    </title> 
  
    <!-- FabricJS CDN -->
    <script src= 
"https://cdnjs.cloudflare.com/ajax/libs/fabric.js/3.6.2/fabric.min.js"> 
    </script> 
</head> 
  
<body> 
    <div style="text-align: center;width: 600px;"> 
        <h1 style="color: green;"> 
            GeeksforGeeks 
        </h1> 
        <b> 
            lock non-uniform scaling of a canvas 
            ellipse using FabricJS 
        </b> 
    </div> 
  
    <div style="text-align: center;"> 
    <canvas id="canvas" width="600" height="200" 
            style="border:1px solid #000000;"> 
    </canvas> 
    </div> 
  
    <script> 
        // Initiate a Canvas instance 
        var canvas = new fabric.Canvas("canvas"); 
  
        // Initiate a Ellipse instance 
        var ellipse = new fabric.Ellipse({ 
            rx: 80, 
            ry: 40, 
            lockUniScaling: true 
        }); 
  
        // Render the Ellipse in canvas 
        canvas.add(ellipse); 
    </script> 
</body> 
  
</html>                    