How to lock the horizontal skewing of Triangle using FabricJS?


In this tutorial, we are going to learn how to lock the horizontal skewing of a Triangle using FabricJS. Just as we can specify the position, colour, opacity and dimension of a triangle object in the canvas, we can also specify whether we want to stop skewing an object horizontally. This can be done by using the lockSkewingX property.

Syntax

new fabric.Triangle({ lockSkewingX : Boolean }: Object)

Parameters

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

Options Keys

  • lockSkewingX − This property accepts a Boolean value. If we assign it a 'true' value, then the object's horizontal skewing will be locked

Example 1

Default behaviour of a Triangle object in the canvas

Let's see a code example to understand the default behaviour of a Triangle object when lockSkewingX property is not used. Skewing the object in both horizontal and vertical directions is feasible by pressing the shift key and then dragging along the horizontal or vertical direction.

<!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 behaviour of a Triangle object in the canvas</h2>
   <p>Press the shift-key and drag the edge along the X-axis or Y-axis and observe that skewing is possible in both directions.</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 triangle object
      var triangle = new fabric.Triangle({
         left: 105,
         top: 70,
         width: 90,
         height: 80,
         fill: "#746cc0",
         stroke: "#967bb6",
         strokeWidth: 5,
      });

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

Example 2

Passing lockSkewingX as key with 'true' value

In this example, we will see how we can cease the ability of a Triangle object to skew horizontally using the lockSkewingX property. As we can see, although we can skew the triangle object vertically, we are not allowed to perform the same action horizontally.

<!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 lockSkewingX as key with 'true' value</h2>
   <p>You can try and see that skewing along the X-axis is no longer feasible.</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 triangle object
      var triangle = new fabric.Triangle({
         left: 105,
         top: 70,
         width: 90,
         height: 80,
         fill: "#746cc0",
         stroke: "#967bb6",
         strokeWidth: 5,
         lockSkewingX: true,
      });

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

Updated on: 24-Jun-2022

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