How to lock the rotation of Ellipse using FabricJS?

FabricJSJavascriptHTML5 Canvas

In this tutorial, we are going to learn how to lock the rotation of an Ellipse using FabricJS. Just as we can specify the position, color, opacity and dimension of an ellipse 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.Ellipse({ lockRotation : Boolean }: Object)

Parameters

  • options (optional) − This parameter is an Object which provides additional customizations to our ellipse. Using this parameter color, 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 an Ellipse object in the canvas

Let's take an example to understand the default behaviour of an ellipse object when lockRotation property is not used. By default, we are able to rotate an ellipse 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>How to lock the rotation of Ellipse using FabricJS</h2>
         <p>You can select the object and rotate it freely, as we have not used the <b>lockRotation</b> property. This is the default behavior. </p>
         <canvas id="canvas"></canvas>
     
         <script>
         // Initiate a canvas instance
         var canvas = new fabric.Canvas("canvas");
         
         // Initiate an ellipse instance
         var ellipse = new fabric.Ellipse({
            left: 115,
            top: 50,
            fill: "white",
            rx: 80,
            ry: 50,
            stroke: "black",
            strokeWidth: 5,
         });

         // Adding it to the canvas
         canvas.add(ellipse);
         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 an ellipse object to rotate by using the lockRotation property. As we can see, as soon as we try to rotate the ellipse 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>How to lock the rotation of Ellipse using FabricJS</h2>
      <p>Here you can select the object but cannot rotate it freely, 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");

         // Initiate an ellipse instance
         var ellipse = new fabric.Ellipse({
            left: 115,
            top: 50,
            fill: "white",
            rx: 80,
            ry: 50,
            stroke: "black",
            strokeWidth: 5,
            lockRotation: true,
         });

         // Adding it to the canvas
         canvas.add(ellipse);
         canvas.setWidth(document.body.scrollWidth);
         canvas.setHeight(250);
      </script>
   </body>
</html>
raja
Updated on 24-May-2022 13:36:06

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