How to lock the flipping during scaling of Rectangle using FabricJS?


In this tutorial, we are going to learn how to lock the flipping during scaling of a Rectangle using FabricJS. Just as we can specify the position, colour, opacity and dimension of a rectangle object in the canvas, we can also specify whether we want to stop flipping an object during scaling. This can be done by using the lockScalingFlip property.

Syntax

new fabric.Rect({ lockScalingFlip : Boolean }: Object)

Parameters

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

Options Keys

  • lockScalingFlip − This property accepts a Boolean value. If we assign it a ‘true’ value, then the object will not be allowed to flip during scaling.

Example 1

Default behaviour of a Rectangle object in the canvas

Let’s see a code example to understand the default behaviour of a rectangle object when lockScalingFlip 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 behaviour of a Rectangle object in the canvas</h2>
   <p>Select a corner and drag the rectangle diagonally to scale it down and then flip it with further dragging.</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 rectangle object
      var rect = new fabric.Rect({
         left: 155,
         top: 90,
         width: 170,
         height: 70,
         fill: "white",
         padding: 9,
         stroke: "#483d8b",
         strokeWidth: 5,
      });

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

Example 2

Passing lockScalingFlip as key with ‘true’ value

In this example, we will see how we can cease the ability of a rectangle object to flip while scaling by using the lockScalingFlip property. As we can see, although we try to flip the rectangle object, it is no longer allowed.

<!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 lockScalingFlip as key with a True value</h2>
   <p>You will no longer be able to flip the rectangle while scaling it.</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 rectangle object
      var rect = new fabric.Rect({
         left: 155,
         top: 90,
         width: 170,
         height: 70,
         fill: "white",
         padding: 9,
         stroke: "#483d8b",
         strokeWidth: 5,
         lockScalingFlip: true,
      });

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

Updated on: 29-Jun-2022

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