How to disable the centered scaling of Rectangle using FabricJS?


In this tutorial, we are going to learn how to disable the centered scaling of Rectangle using FabricJS. Rectangle is one of the various shapes provided by FabricJS. In order to create a rectangle, we will have to create an instance of fabric.Rect class and add it to the canvas. When being scaled via controls, assigning a true value to the centeredScaling property, uses the center as the object's origin of transformation.

Syntax

new fabric.Rect({ centeredScaling: 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 centeredScaling is a property.

Options Keys

  • centeredScaling − This property accepts a Boolean value. When this property is true, the object uses the center as its origin of transformation.

Example 1

Passing centeredScaling as key and assigning a “true” value to it

Let’s see a code example to see how a rectangle object behaves when centeredScaling property is enabled. When we scale the object up the origin of transformation is the center of the rectangle.

<!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 centeredScaling as key and assigning a "true" value to it</h2>
   <p>Try scaling the rectangle to see that centered scaling has been enabled</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: 125,
         top: 90,
         width: 170,
         height: 70,
         fill: "#cf1020",
         borderColor: "black",
         borderScaleFactor: 3,
         centeredScaling: true,
      });

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

Example 2

Disabling centeredScaling property

We can disable the centeredScaling property by assigning it a False value. This will not use the center of the rectangle as the center of transformation anymore. Here is a code example to demonstrate that −

<!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>Disabling the centeredScaling property</h2>
   <p>Try scaling the rectangle to see that centered scaling has been disabled</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: 125,
         top: 90,
         width: 170,
         height: 70,
         fill: "#cf1020",
         borderColor: "black",
         borderScaleFactor: 3,
         centeredScaling: false,
      });

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

Updated on: 29-Jun-2022

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