How to enable retina scaling for cloned image using FabricJS?

In this tutorial, we are going to learn how to enable retina scaling for a cloned 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 enable retina scaling for a cloned image, we use the enableRetinaScaling property. In this case, the clone image is scaled up by the devicePixelRatio for better rendering on retina screens. There will be no change on the appearance of the image.

Syntax

cloneAsImage( callback: function, { enableRetinaScaling : Boolean }: Object): fabric.Object

Parameters

  • callback (optional) − This parameter is a function which is to be invoked with a cloned image instance as the first argument.

  • options (optional) − This parameter is an optional Object which provides additional customizations to our clone image. Using this parameter we can set a multiplier, crop the clone image, remove the current object transform or a lot of other properties can be changed of which enableRetinaScaling is a property.

Options Keys

  • enableRetinaScaling − This property accepts a Boolean value which allows us to enable retina scaling for the clone image.

Using the enableRetinaScaling property and passing it a ‘false’ value

Example

Let’s see a code example of how the cloned Image object appears when the enableRetinaScaling property is used and a ‘false’ value is passed to it. In this case, retina scaling will not be enabled.

<!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 enableRetinaScaling property and passing it a ‘false’ value
   </h2>
   <p>You can see the cloned image with retina scaling disabled</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 a shadow object
      var shadow = new fabric.Shadow({
         color: "black",
         blur: 12,
      });
      // Initiate an Image object
      var image = new fabric.Image(imageElement, {
         top: 50,
         left: 110,
         skewX: 20,
         shadow: shadow,
      });
      
      // Using cloneAsImage method
      image.cloneAsImage(
         function(Img) {
            Img.set("top", 150);
            Img.set("left", 150);
            canvas.add(Img);
         }, {
            enableRetinaScaling: false,
         }
      );
   </script>
</body>
</html>

Using the enableRetinaScaling property and passing it a ‘true’ value

Example

In this example, we have used the enableRetinaScaling property and passed it a ‘true’ value. Thus, retina scaling will be enabled for our clone image.

<!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 enableRetinaScaling property and passing it a ‘true’ value
   </h2>
   <p>You can see cloned image with retina scaling enabled</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 a shadow object
      var shadow = new fabric.Shadow({
         color: "black",
         blur: 12,
      });
      
      // Initiate an Image object
      var image = new fabric.Image(imageElement, {
         top: 50,
         left: 110,
         skewX: 20,
         shadow: shadow,
      });
      
      // Using cloneAsImage method
      image.cloneAsImage(
         function(Img) {
            Img.set("top", 150);
            Img.set("left", 150);
            canvas.add(Img);
         }, {
            enableRetinaScaling: true,
         }
      );
   </script>
</body>
</html>

Updated on: 27-Oct-2022

354 Views

Related Articles

Kickstart Your Career

Get certified by completing the course

Get Started
Advertisements