How to change the font size of Text using FabricJS?

In this tutorial, we are going to see how to change the font size of a Text using FabricJS. We can display text on canvas by adding an instance of fabric.Text. Not only does it allow us to move, scale and change the dimensions of the text but it also provides additional functionality like text alignment, text decoration, line height which can be obtained by the properties textAlign, underline and lineHeight respectively. The font size specifies how large or small the characters, displayed in our Text object, should be. We can change the font size by using the fontSize property

Syntax

new fabric.Text(text: String , { fontSize: Number }: Object)

Parameters

text − This parameter accepts a String which is the text string that we want to display.
options (optional) − This parameter is an Object which provides additional customizations to our text. Using this parameter colour, cursor, stroke width and a lot of other properties can be changed related to the object of which fontSize is a property.

Options Keys

fontSize − This property accepts a Number which allows us to set the size of the text inside our text. Its default value is 40.

Example 1

Default appearance of the Text object

Let’s see a code example to understand how our text object would appear when the fontSize property is not used.


<!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 appearance of the Text object</h2>
   <p>You can see the default value of text which is 40</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 text object
      var text = new fabric.Text("Add Sample Text Here", {
         width: 200,
         left: 50,
         top: 70,
         fill: "#000060",
      });

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

Example 2

Passing the fontSize property as key with a custom value

In this example, we are passing the fontSize property as key, with a value of 30. This means that our text object will now be rendered with text whose font size is 30px.


<!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 the fontSize property as key with a custom value</h2>
   <p>You can see the font size is 30 now which is slightly smaller than the default</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 text object
      var text = new fabric.Text("Add Sample Text Here", {
         width: 200,
         left: 50,
         top: 70,
         fill: "#000060",
         fontSize: 30,
      });

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