How to lock the rotation of a Circle using FabricJS?

FabricJSJavascriptHTML5 Canvas

In this tutorial, we are going to learn how to lock the rotation of a Circle using FabricJS. Just as we can specify the position, colour, opacity and dimension of a circle object in the canvas, we can also specify whether we want it to rotate or not. This can be done by using the lockRotation property.

Syntax

new fabric.Circle({ lockRotation : Boolean }: Object)

Parameters

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

Options Keys

  • lockRotation − This property accepts a Boolean value. If we assign it a 'true' value, then the object rotation will be locked.

Example 1

Default behaviour of a Circle object in the canvas

Let's see an example to understand the default behaviour of a Circle object when lockRotation property is not used. By default, we can rotate a circle object anticlockwise or clockwise.

<!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>Locking the rotation of circle using FabricJS</h2>
      <p>Select the object and try to rotate it by holding its controlling corner at the top. You can rotate it freely in both clockwise or anticlockwise direction. This is the default behavior. Here we have not used the <b>lockRotation</b> property, but by default, it is set to False. </p>
      <canvas id="canvas"></canvas>

      <script>
         // Initiate a canvas instance
         var canvas = new fabric.Canvas("canvas");
         var circle = new fabric.Circle({
            left: 115,
            top: 50,
            fill: "white",
            radius: 50,
            stroke: "black",
            strokeWidth: 5
         });

         // Adding it to the canvas
         canvas.add(circle);
         canvas.setWidth(document.body.scrollWidth);
         canvas.setHeight(250);
      </script>
   </body>
</html>

Example 2

Passing lockRotation as key with 'true' value

In this example, we will see how we can cease the ability of a circle object to rotate by using the lockRotation property. As soon as we try to rotate the circle object, a not-allowed cursor is shown. This means that the rotation action is no longer allowed.

<!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>Locking the rotation of a circle using FabricJS</h2>
      <p>Select the object and try to rotate it. Now you won't be able to rotate the circle, as we have set <b>lockRotation</b> to True. </p>
      <canvas id="canvas"></canvas>

      <script>
         // Initiate a canvas instance
         var canvas = new fabric.Canvas("canvas");
         var circle = new fabric.Circle({
            left: 115,
            top: 50,
            fill: "white",
            radius: 50,
            stroke: "black",
            strokeWidth: 5,
            lockRotation: true
         });

         // Adding it to the canvas
         canvas.add(circle);
         canvas.setWidth(document.body.scrollWidth);
         canvas.setHeight(250);
      </script>
   </body>
</html>
raja
Updated on 25-May-2022 11:50:58

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