How to set the size of the controlling corners of Rectangle using FabricJS?

In this tutorial, we are going to learn how to set the size of the controlling corners of a Rectangle using FabricJS. The controlling corners of an object allow us to scale, stretch or change its position.

We can customize our controlling corners in many ways such as adding a specific colour to it, changing its size etc. We can change the size by using the cornerSize property.

Syntax

new fabric.Rect({ cornerSize: Number }: Object)

Parameters

  • Options (optional) − This parameter is an Object which provides additional customizations to our rectangle. 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 cornerSize is a property.

Options keys

  • cornerSize − This property accepts a Number which allows us to manipulate the size of the controlling corners of a selected object. Its default value is 13.

Example 1

Default size of the controlling corners

Let’s see a code example that depicts the default size of the controlling corners of a rectangle object when it is actively selected.

<!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>Default size of the controlling corners</h2>
   <p>Select the rectangle to see the default size of the controlling corners</p>
   <canvas id="canvas"></canvas>
   <script>
      // Initiate a canvas instance
      var canvas = new fabric.Canvas("canvas");
      canvas.setWidth(document.body.scrollWidth);
      canvas.setHeight(250);

      // Initiate a rectangle object
      var rect = new fabric.Rect({
         left: 125,
         top: 90,
         width: 170,
         height: 70,
         fill: "#cf1020",
         borderColor: "black",
         borderScaleFactor: 3,
         cornerColor: "#3b7a57",
      });

      // Add it to the canvas
      canvas.add(rect);
   </script>
</body>
</html>

Example 2

Passing cornerSize as key with a custom value

In this example, we are passing the cornerSize property as key with a value of 17. We can see how that changes the size of our controlling corners when the rectangle object is selected.

<!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>Passing cornerSize as key with a custom value</h2>
   <p>Select the rectangle to see the size of the controlling corners</p>
   <canvas id="canvas"></canvas>
   <script>
      // Initiate a canvas instance
      var canvas = new fabric.Canvas("canvas");
      canvas.setWidth(document.body.scrollWidth);
      canvas.setHeight(250);

      // Initiate a rectangle object
      var rect = new fabric.Rect({
         left: 125,
         top: 90,
         width: 170,
         height: 70,
         fill: "#cf1020",
         borderColor: "black",
         borderScaleFactor: 3,
         cornerColor: "#3b7a57",
         cornerSize: 17,
      });

      // Add it to the canvas
      canvas.add(rect);
   </script>
</body>
</html>

Updated on: 30-Jun-2022

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