Fabric.js line borderOpacityWhenMoving Property

Last Updated : 22 Jan, 2021

In this article, we are going to see how to draw a canvas Line in which border opacity will change when user is moving the line using FabricJS. The canvas line means the line is movable and can be stretched according to requirement. Further, the line can be customized when it comes to initial stroke color, height, width, fill color, or stroke width.

Syntax:

fabric.line({
    borderOpacityWhenMoving : Number
});

Approach: To make this 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 line. After this, we will initialize instances of Canvas and line provided by FabricJS and set the opacity of the border of the canvas line when moving using borderOpacityWhenMoving property, and render the line on the Canvas as given below.

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

borderOpacityWhenMoving: It specifies the opacity of the border while moving this parameter takes value ranging from 0 to 1. It contains a Number value.

Example 1:

HTML

<!DOCTYPE html> 
<html> 
  
<head> 
    <script src= 
"https://cdnjs.cloudflare.com/ajax/libs/fabric.js/3.6.2/fabric.min.js"> 
    </script> 
</head> 
  
<body> 
    <h1> 
        fabric.js | line borderOpacityWhenMoving property 
    </h1> 
      
    <canvas id="canvas" width="600" height="200" 
        style="border:1px solid #000000;">  
    </canvas> 
  
    <script> 
        var canvas = new fabric.Canvas("canvas"); 
  
        var line = new fabric.Line([150, 10, 220, 150], { 
            stroke: 'green', 
            borderOpacityWhenMoving: 0 
        }); 
  
        canvas.add(line); 
    </script> 
</body> 
  
</html> 

Output:

Example 2:

HTML

<!DOCTYPE html> 
<html> 
  
<head> 
    <script src= 
"https://cdnjs.cloudflare.com/ajax/libs/fabric.js/3.6.2/fabric.min.js"> 
    </script> 
</head> 
  
<body> 
    <h1> 
        fabric.js | line borderOpacityWhenMoving property 
    </h1> 
      
    <canvas id="canvas" width="600" height="200"
        style="border:1px solid #000000;">  
    </canvas> 
  
    <script> 
        var canvas = new fabric.Canvas("canvas"); 
  
        var line = new fabric.Line([150, 10, 220, 150], { 
            stroke: 'green', 
            borderOpacityWhenMoving: 0.2 
        }); 
  
        canvas.add(line); 
    </script> 
</body> 
  
</html> 