Fabric.js Polygon lockScalingFlip Property

In this article, we are going to see how to lock flipping by scaling a canvas polygon using FabricJS so that it cannot be inverted by pulling the width to the negative side. The canvas polygon means the polygon is movable and can be stretched according to requirement. Further, the polygon 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 polygon. After this, we will initialize instances of Canvas and polygon provided by FabricJS and lock flipping by scaling of the polygon using lockScalingFlip 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 }],
    {
         lockScalingFlip: boolean
    });

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

  • lockScalingFlip: It specifies whether to lock flipping by scaling or not.

Note: Dimension pixels is must create a polygon.



Below examples illustrate the Fabric.JS Polygon lockScalingFlip property in JavaScript:

Example 1:

HTML

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<!DOCTYPE html> 
<html
  
<head
    <!-- Loading the FabricJS library -->
    <script src
    </script
</head
  
<body
    <div style="text-align: center;width: 600px;"
    <h1 style="color: green;"
        GeeksforGeeks 
    </h1
    <b
        Fabric.js | Polygon lockScalingFlip 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 }], { 
            fill: 'green',
            lockScalingFlip: true
        }); 
  
        // Render the polygon in canvas 
        canvas.add(polygon); 
    </script
</body
  
</html>

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Output: 

Example 2:

HTML

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<!DOCTYPE html> 
<html
  
<head
    <!-- Loading the FabricJS library -->
    <script src
    </script
</head
  
<body
    <div style="text-align: center;width: 600px;"
    <h1 style="color: green;"
        GeeksforGeeks 
    </h1
    <b
        Fabric.js | Polygon lockScalingFlip 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 }], { 
            fill: 'green',
            lockScalingFlip: false
        }); 
  
        // Render the polygon in canvas 
        canvas.add(polygon); 
    </script
</body
  
</html>

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Output: 

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