How to get the opacity of Image object using FabricJS?

FabricJS Javascript HTML5 Canvas

In this tutorial, we are going to learn how to get the opacity of Image using FabricJS. We can create an Image object by creating an instance of fabric.Image. Since it is one of the basic elements of FabricJS, we can also easily customize it by applying properties like angle, opacity etc. In order to get the opacity of Image, we use the getObjectOpacity method.

Syntax

getObjectOpacity(): Number

Using the getObjectOpacity method

Example

Let’s see a code example to see the logged output when the getObjectOpacity method is used. In this case, the default opacity will be displayed in the console which is 1.


<!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 getObjectOpacity method</h2>
   <p>
      You can open console from dev tools and see that the logged value is
      being displayed in the console
   </p>
   <canvas id="canvas"></canvas>
   <img src="https://www.tutorialspoint.com/images/logo.png" id="img1" style="display: none" />
   <script>
      // Initiate a canvas instance
      var canvas = new fabric.Canvas("canvas");
      canvas.setWidth(document.body.scrollWidth);
      canvas.setHeight(250);
      
      // Initiating the image element
      var imageElement = document.getElementById("img1");
      
      // Initiate an Image object
      var image = new fabric.Image(imageElement, {
         top: 50,
         left: 110,
      });
      
      // Add it to the canvas
      canvas.add(image);
      
      // Using getObjectOpacity method
      console.log("The opacity is: ", image.getObjectOpacity());
   </script>
</body>
</html>

Using the getObjectOpacity method and passing the opacity property

Example

Let’s see a code example to see the logged output when the getObjectOpacity method is used in conjunction with the opacity property. In this case, the opacity of the image object has been assigned a value of 0.7 and hence the logged output will be 0.7.


<!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 getObjectOpacity method and passing the opacity property</h2>
   <p>
      You can open console from dev tools and see that the opacity value is being displayed in the console
   </p>
   <canvas id="canvas"></canvas>
   <img src="https://www.tutorialspoint.com/images/logo.png" id="img1" style="display: none" />
   <script>
      // Initiate a canvas instance
      var canvas = new fabric.Canvas("canvas");
      canvas.setWidth(document.body.scrollWidth);
      canvas.setHeight(250);
      
      // Initiating the image element
      var imageElement = document.getElementById("img1");
      
      // Initiate an Image object
      var image = new fabric.Image(imageElement, {
         top: 50,
         left: 110,
         opacity: 0.7,
      });
      
      // Add it to the canvas
      canvas.add(image);
      
      // Using getObjectOpacity method
      console.log("The opacity is: ", image.getObjectOpacity());
   </script>
</body>
</html>

Rahul Gurung

Updated on: 27-Oct-2022

150 Views

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