How to add line height to multiline text in IText using FabricJS?

In this tutorial, we are going to learn about how to add line height to multiline text in IText object using FabricJS. The IText class was introduced in FabricJS version 1.4, extends fabric.Text and is used to create IText instances. An IText instance gives us the freedom to select, cut, paste or add new text without additional configurations.

There are also various supported key combinations and mouse/touch combinations which make text interactive which are not provided in Text. Textbox, however, which is based on IText allows us to resize the text rectangle and wraps lines automatically. This is not true for IText as height is not adjusted based on the wrapping of lines. We can manipulate our IText object by using various properties. Similarly, we can add extra height between lines by using the lineHeight property.

Syntax

new fabric.IText(text: String, { lineHeight: 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 IText object. Using this parameter colour, cursor, border width and a lot of other properties can be changed related to the object of which lineHeight is a property.

Options Keys

  • ineHeight − This property accepts a Number that allows us to control the height between each line. Default value of lineHeight property is 1.16.

Example 1

Default appearance of IText object

Let’s see a code example to see how our IText object looks like with the default value of lineHeight property. We will not pass any lineHeight key to the class in this example as given below −

<!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 IText object</h2>
   <p>You can see the default line height in this example</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 an itext object
      var itext = new fabric.IText(
         "Add sample text here.
Lorem ipsum dolor sit amet",
         {
            width: 300,
            left: 210,
            top: 70,
            fill: "green",
         }
      );

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

Example 2

Passing the lineHeight property as key

In this example, we will see how assigning a value to the lineHeight property changes the space between each line in an IText object. Here we have used 2 as lineHeight which thus increases the height between each line.

<!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 lineHeight property as key</h2>
   <p>You can see our IText object now has a line height of 2</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 an itext object
      var itext = new fabric.IText(
         "Add sample text here.
Lorem ipsum dolor sit amet",
         {
            width: 300,
            left: 210,
            top: 70,
            fill: "green",
            lineHeight: 2,
         }
      );

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

Updated on: 12-Sep-2022

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