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Fabric.js | Rect opacity Property
  • Last Updated : 20 May, 2020

In this article, we are going to see how to set the opacity of a rectangle canvas using FabricJS. The canvas rectangle means rectangle is movable and can be stretched according to requirement. Further, the rectangle can be customized when it comes to initial stroke color, height, width, fill color, or stroke width.

To make it possible, we are going to use a JavaScript library called FabricJS. After importing the library, we will create a canvas block in the body tag which will contain the rectangle. After this, we will initialize instances of Canvas and Rect provided by FabricJS and set the opacity of the rectangle using opacity property and render the Rect on the Canvas as given in the example below.

Syntax:

fabric.Rect({
    width: number,
    height: number,
    opacity: number
});

Parameters: This function accepts three parameters as mentioned above and described below:

  • width: It specifies the width of rectangle.
  • height: It specifies the height of rectangle.
  • opacity: It specifies the opacity of the canvas rectangle.

Example: This example uses FabricJS to set opacity of a canvas rectangle.




<!DOCTYPE html> 
<html> 
  
<head> 
    <title> 
        Fabric.js | Rect opacity Property
    </title> 
      
    <!-- Adding the FabricJS library -->
    <script src= 
    </script> 
</head> 
  
<body> 
    <div style="text-align: center;width: 600px;"
        <h1 style="color: green;"
            GeeksforGeeks 
        </h1> 
        <b> 
            Fabric.js | Rect opacity Property 
        </b> 
    </div>
    <canvas id="canvas" width="600" height="200"
        style="border:1px solid #000000"
    </canvas> 
      
    <script> 
      
        // Initiate a Canvas instance 
        var canvas = new fabric.Canvas("canvas"); 
  
        // Initiate a Rect instance 
        var rectangle = new fabric.Rect({ 
            width: 200,
            height: 100,
            fill: ''
            stroke: 'green',
            strokeWidth: 3,
            opacity: .3
        }); 
  
        // Render the Rect in canvas 
        canvas.add(rectangle); 
        canvas.centerObject(rectangle);
    </script> 
</body> 
  
</html>                    

Output:




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