Fabric.js Polyline lockUniScaling Property

Last Updated : 02 Feb, 2021

In this article, we are going to see how to lock non-uniform scaling of a canvas polyline using FabricJS so that the aspect ratio of the object is maintained. The canvas polyline means the polyline is movable and can be stretched according to requirements. Further, the polyline 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 that will contain the polyline. After this, we will initialize instances of Canvas and polyline provided by FabricJS and lock the non-uniform scaling of the canvas polyline using lockUniScaling property and render the polyline on the Canvas as given in the example below.

Syntax:

var polyline = new fabric.Polyline(Points, { 
            lockUniScaling: true
        });

Parameters: This property accepts two parameters as mentioned above and described below:

points: It holds the starting and ending coordinates for all the points of the polyline.
lockUniScaling: It specifies whether to lock non-uniform scaling or not.

Example:

HTML

<!DOCTYPE html>  
<html>  
  
<head>  
    <title>  
        Fabric.js | Polyline lockUniScaling Property  
    </title>  
  
    <!-- 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 lockUniScaling 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  }], {  
            lockUniScaling: true 
        });  
  
        // Render the polyline in canvas  
        canvas.add(polyline);  
    </script>  
</body>  
  
</html>