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FabricJS - How to enable retina scaling in the URL string of a Line object?

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Sep 15, 2023 am 09:21 AM

FabricJS – 如何在 Line 对象的 URL 字符串中启用视网膜缩放？

In this tutorial, we will learn how to enable retina scaling in a URL string of a Line object using FabricJS. Line element is one of the basic elements provided in FabricJS. It is used to create straight lines. Since line elements are geometrically one-dimensional and contain no interiors, they are never filled. We can create a line object by creating a fabric.Line instance, specifying the x and y coordinates of the line and adding it to the canvas. To enable retina scaling in the URL string of a Line object, we use the enableRetinaScaling property. This has no effect on the image itself, but the canvas is scaled by devicePixelRatio to render better on retina screens.

Syntax

 toDataURL({ enableRetinaScaling: Boolean }: Object): String

Parameters

Options (optional) - This parameter is a provided Additional Custom Objects The URL representation of the Line object. Height, mass, multiplier, and many other properties can be changed using this parameter, of which enableRetinaScaling is a property.

Option Key h3>

##enableRetinaScaling: This property accepts Boolean Value that allows us to enable retina scaling for the image.

Using the

enableRetinaScaling attribute and passing it an error value

Example Let’s look at a code example to see Output logged when using the toDataURL method without using the

enableRetinaScaling attribute. Once we open the console from the dev tools, we can see the URL representation of the Line object. We can copy the URL and paste it into the address bar of a new tab to see the final output. Since we have passed a false value to the enableRetinaScaling property, 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 id="Using-the-enableRetinaScaling-property-and-passing-it-a-false-value">Using the enableRetinaScaling property and passing it a false value</h2>
   <p>
      You can open console from dev console and see the URL representation with retina scaling 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 Line object
      var line = new fabric.Line([200, 100, 100, 40], {
         stroke: "blue",
         strokeWidth: 20,
         angle: 70,
      });
      
      // Add it to the canvas
      canvas.add(line);
      // Using the toDataURL method
      console.log(line.toDataURL({
         enableRetinaScaling: false
      }));
   </script>
</body>
</html>

Use the

enableRetinaScaling attribute and pass it a true value

Example

Let’s look at a code example to see when

enableRetinaScaling The property has been passed a true value. In this case, retina scaling will 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 id="Using-the-enableRetinaScaling-property-and-passing-it-a-true-value">Using the enableRetinaScaling property and passing it a true value</h2>
   <p>
      You can open console from dev console and see the URL representation with retina scaling 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 Line object
      var line = new fabric.Line([200, 100, 100, 40], {
         stroke: "blue",
         strokeWidth: 20,
         angle: 70,
      });
      
      // Add it to the canvas
      canvas.add(line);
      
      // Using the toDataURL method
      console.log(line.toDataURL({
         enableRetinaScaling: true
      }));
   </script>
</body>
</html>

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