How to center an object horizontally with respect to current viewport of canvas in IText using FabricJS?

FabricJS Javascript HTML5 Canvas

In this tutorial, we are going to learn about how to center an object horizontally with respect to current viewport of canvas in IText 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. Likewise, we can center an object horizontally with respect to current viewport of canvas by using the viewportCenterH method.

Syntax

viewportCenterH(): fabric.Object

Example 1

Default appearance of the IText object

Let’s see a code example to see how our IText object looks when the viewportCenterH method is not used. In this case, the IText object will not be centered horizontally on the canvas.


<!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 IText object</h2>
   <p>You can see that the itext object has not been centered horizontally with respect to the current viewport of canvas</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.", {
         width: 300,
         left: 50,
         top: 70,
         fill: "red",
      });

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

Example 2

Using the viewportCenterH method

Let’s see a code example to see how the IText object looks like when the viewportCenterH method is used. In this case, our IText object will be centered horizontally with respect to the current viewport of the canvas.


<!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>Using the viewportCenterH method</h2>
   <p>You can see that the itext object has been centered horizontally with respect to the current viewport of canvas</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.", {
         width: 300,
         left: 50,
         top: 70,
         fill: "red",
      });

      // Add it to the canvas
      canvas.add(itext);

      // Using the viewportCenterH method
      itext.viewportCenterH();
   </script>
</body>
</html>

Rahul Gurung

Updated on: 12-Sep-2022

98 Views

Kickstart Your Career

Get certified by completing the course

Get Started