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How to scale controlling border of a canvas circle using Fabric.js ?

  • Last Updated : 12 May, 2020

In this article, we are going to see how to scale controlling border of a canvas circle using FabricJS. The canvas means the circle is movable and can be stretched according to requirement. Further, the circle can be customized when it comes to initial stroke color, fill color, stroke width or radius.

Approach: 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 circle. After this, we will initialize instances of Canvas and Circle provided by FabricJS and scale controlling border of the circle using borderScaleFactor property and render the Circle on the Canvas as given in the example below.


    radius: number,
    borderScaleFactor: number

Parameters: This function accepts two parameters as mentioned above and described below:

  • radius: It specifies the radius.
  • borderScaleFactor: It specifies the size of the controlling border.

Example: This example uses FabricJS to scale controlling border of a canvas circle. Note that you have to click on the object to see the border.

<!DOCTYPE html>
        How to scale controlling border of
        a canvas circle using FabricJS?
    <!-- FabricJS CDN -->
    <script src=
    <canvas id="canvas" width="600" height="200"
        style="border:1px solid #000000">
        // Initiate a Canvas instance
        var canvas = new fabric.Canvas("canvas");
        // Initiate a Circle instance
        var circle = new fabric.Circle({
            radius: 50,
            borderScaleFactor: 5
        // Render the circle in canvas


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