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

In this tutorial, we are going to learn how to set the size of the controlling corners of a Textbox 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.Textbox(text: String, { cornerSize: Number }: Object)

Parameters

text − This parameter accepts a String which is the text string that we want to display inside our textbox.
options (optional) − This parameter is an Object which provides additional customizations to our textbox. 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 textbox 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>You can select the textbox 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 textbox object
		var textbox = new fabric.Textbox("The best way to teach your kids about taxes is by eating 30 percent of their ice cream.", {
			backgroundColor: "rgba(204,255,0,0.2)",
			width: 400,
			top: 20,
			left: 110,
			cornerColor: "#87a96b",
		});
		
		// Add it to the canvas
		canvas.add(textbox);
	</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 textbox 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>You can select the textbox 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 textbox object
		var textbox = new fabric.Textbox("The best way to teach your kids about taxes is by eating 30 percent of their ice cream.", {
			backgroundColor: "rgba(204,255,0,0.2)",
			width: 400,
			top: 70,
			left: 110,
			cornerColor: "#87a96b",
			cornerSize: 17,
		});
		
		// Add it to the canvas
		canvas.add(textbox);
	</script>
</body>
</html>