How to create an Object representation of a Line object using FabricJS?

In this tutorial, we are going to learn about how to create an Object representation of a Line object using FabricJS. A Line element is one of the basic elements provided in FabricJS. It is used for creating straight lines. Because line elements are geometrically one-dimensional and do not contain an interior, they are never filled. We can create a line object by creating an instance of fabric.Line, specifying the x and y coordinates of the line and adding it to the canvas. In order to create an Object representation of a Line object, we use the toObject method.

Syntax

toObject(propertiesToInclude: Array): fabric.Object

Parameters

propertiesToInclude − This parameter accepts an Array which contains any properties we might want to additionally include in the output. This parameter is optional.

Using the toObject method

Example

Let’s see a code example to see the logged output when the toObject method is used. In this case, an Object representation of the line instance will be returned.


<!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 toObject method</h2>
   <p>
      You can open console from dev tools and see that the logged output contains the Object representation of the line instance
   </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 Line object
      var line = new fabric.Line([200, 100, 100, 40], {
         stroke: "blue",
         strokeWidth: 20,
      });
      
      // Add it to the canvas
      canvas.add(line);
      
      // Using the toObject method
      console.log("Object representation of the Line instance is: ", line.toObject());
   </script>
</body>
</html>

Using toObject method to add additional properties

Example

Let’s see a code example to see how we can include additional properties by using the toObject method. In this case, we have added a custom property called “PropertyName”. We can pass the specific property to the fabric.Line instance as second argument in options object and pass same key to the toObject method.


<!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 toObject method to add additional properties</h2>
   <p>
      You can open console from dev tools and see that the logged output contains added property called PropertyName
   </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 Line object with PropertyName key
      // passed in options object
      var line = new fabric.Line([200, 100, 100, 40], {
         stroke: "blue",
         strokeWidth: 20,
         PropertyName: "property",
      });
      
      // Add it to the canvas
      canvas.add(line);
      
      // Using the toObject method
      console.log(
         "Object representation of the Line instance is: ",
         line.toObject(["PropertyName"])
      );
   </script>
</body>
</html>