Fabric.js Polygon strokeUniform Property

Last Updated : 18 Jan, 2021

In this article, we are going to see how to lock the uniform stroke width of a canvas Polygon using FabricJS so that width of the stroke remains the same even when we scale the object to a bigger size. The canvas means the Polygon is movable and can be stretched according to the requirement. Further, the Polygon can be customized when it comes to initial stroke color, fill color, stroke width, or size.

Approach:

The FabricJS JavaScript library is used for the above. After importing the library using CDN, we will create a canvas block in the body tag which will contain our Polygon. After this, we will initialize instances of Canvas and Polygon provided by FabricJS and lock uniform stroke width of the canvas Polygon using strokeUniform property and render the polygon on the canvas as given in the example below.

Syntax:

fabric.Polygon([  
    { x: pixel, y: pixel },  
    { x: pixel, y: pixel },  
    { x: pixel, y: pixel},  
    { x: pixel, y: pixel},  
    { x: pixel, y: pixel }], {
        strokeUniform: string
    }
);

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

strokeUniform: When “false“, the stoke width will scale with the object. When “true”, the stroke will always match the exact pixel size entered for stroke width. The default value is “false”.

Note: Dimension pixels must create a polygon.

Example: Below example illustrates the Fabric.JS Polygon strokeUniform in JavaScript.

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 | Polygon strokeUniform 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 polygon instance  
        var polygon = new fabric.Polygon([ 
            { x: 295, y: 10 }, 
            { x: 235, y: 198 }, 
            { x: 385, y: 78 }, 
            { x: 205, y: 78 }, 
            { x: 355, y: 198 }], { 
            stroke: 'green', 
            strokeWidth: 5, 
            strokeUniform: false, 
        }); 
  
        // Render the polygon in canvas  
        canvas.add(polygon);  
    </script> 
</body> 
  
</html> 