How to create a canvas with Circle using FabricJS?



In this tutorial, we are going to learn about how to create a canvas with a Circle object using FabricJS. Circle is one of the various shapes provided by FabricJS. In order to create a circle, we will have to create an instance of fabric.Circle class and add it to the canvas.

Syntax

new fabric.Circle({ radius: Number }: Object)

Parameters

  • options (optional) − This parameter is an Object which provides additional customizations to our object. Using this parameter, properties such as colour, cursor, stroke width and a lot of other properties can be changed related to the circle of which radius is a property.

Options Keys

  • radius − This property accepts a Number which determines the radius of the circle. If we don't specify a radius, our circle would not be displayed on our canvas.

Example 1

Creating an instance of fabric.Circle() and adding it to our canvas

Let's see an example of how we can add a circle to our canvas. Here we have created a circle with radius 50px. The stroke property signifies the border-colour and strokeWidth specifies how wide it shall be. We have used sky-blue colour to fill in our object whose hexadecimal value is #80daeb.

<!DOCTYPE html> <html>    <head>       <!-- Adding the Fabric JS Library-->       <script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/510/fabric.min.js"></script>    </head>    <body>       <h2>Creating a canvas with circle using FabricJS</h2>          <p>Here we have created a circle of radius 50px over a canvas. In addition, we have used the <b>fill</b> and <b>stroke</b> properties to color its body and outline. </p>       <canvas id="canvas"></canvas>       <script>          // Initiate a canvas instance          var canvas = new fabric.Canvas("canvas");                    // Creating an instance of the fabric.Circle class          var circle = new fabric.Circle({             left: 215,             top: 100,             radius: 50,             fill: "#80daeb",             stroke: "#00b7eb",             strokeWidth: 2,          });                    // Adding it to the canvas          canvas.add(circle);          canvas.setWidth(document.body.scrollWidth);          canvas.setHeight(250);       </script>    </body> </html>

Example 2

Manipulating the Circle object by using the set method

In this example, we have assigned the properties to the circle by using the set method which is a setter for values. Any property related to stroke, strokeWidth, radius, scaling, rotation, etc., can be mutated by using this method.

<!DOCTYPE html> <html>    <head>       <!-- Adding the Fabric JS Library-->       <script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/510/fabric.min.js"></script>    </head>        <body>       <h2>Creating a canvas with circle using FabricJS</h2>       <p>Here we have used the <b>set</b> method to create a circle of radius 40px and then filled the object with a color. </p>       <canvas id="canvas"></canvas>       <script>          // Initiate a canvas instance          var canvas = new fabric.Canvas("canvas");          var circle = new fabric.Circle();          canvas.add(circle);                    // Use set to set the properties          circle.set("radius", 40);          circle.set("fill", "green");          circle.set({             stroke: "rgba(133, 187, 101, 0.7)",             strokeWidth: 4          });          circle.set("left", 50);          circle.set("top", 50);          canvas.setWidth(document.body.scrollWidth);          canvas.setHeight(250);       </script>    </body> </html>
Updated on: 2022-05-25T07:38:42+05:30

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