How to create a canvas with Circle using FabricJS?

FabricJSJavascriptHTML5 Canvas

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>
raja
Updated on 25-May-2022 07:38:42

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