Fabric.js Polyline borderOpacityWhenMoving Property

Last Updated : 22 Jan, 2021

In this article, we are going to see how to change border opacity while moving a canvas Polyline using FabricJS. The canvas means the Polyline is movable and can be stretched according to requirements. Further, the circle can be customized when it comes to initial stroke color, fill color, stroke width, or radius.

To make it possible, we are going to use a JavaScript library called FabricJS. After importing the library using CDN, we will create a canvas block in the body tag that will contain our Polyline. After this, we will initialize instances of Canvas and Polyline provided by FabricJS and change border opacity while moving the Polyline using borderOpacityWhenMoving property and render the Polyline on the Canvas as given in the below example.

Syntax:

var polyline = new fabric.Polyline(Points, {  
    borderOpacityWhenMoving: number
});

Parameters: This property accepts a single parameter as mentioned above and described below:

borderOpacityWhenMoving: It specifies the opacity of the border while it is moving. The default value is 0.4.

The below example illustrates the borderOpacityWhenMovingproperty in Fabric.js:

Example:

HTML

<!DOCTYPE html>  
<html>  
<head>  
  
    <!-- Loading the FabricJS library -->
    <script src=  
"https://cdnjs.cloudflare.com/ajax/libs/fabric.js/3.6.2/fabric.min.js">  
    </script>  
</head>  
  
<body>  
    <div style="text-align: center;width: 600px;">  
        <h1 style="color: green;">  
            GeeksforGeeks  
        </h1>  
        <b>  
            Fabric.js | Polyline borderOpacityWhenMoving 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 polyline instance  
        var polyline = new fabric.Polyline([  
        { x: 200,  
            y: 10 },  
        {x: 250,  
            y: 50  
        }, {  
            x: 250,  
            y: 180  
        }, {  
            x: 150,  
            y: 180  
        }, {  
            x: 150,  
            y: 50  
        }, {  
            x: 200,  
            y: 10 }], {  
            borderColor: 'green', 
            borderOpacityWhenMoving: 1 
        });  
  
        // Render the polyline in canvas  
        canvas.add(polyline);  
    </script>  
</body>  
  
</html>