How to set the angle of a Line in FabricJS?

In this tutorial, we are going to learn about how to set the angle of a Line object using FabricJS. A Line element is one of the basic elements provided in FabricJS. It is used for creating straight lines. Because line elements are geometrically one-dimensional and do not contain an interior, they are never filled. We can create a line object by creating an instance of fabric.Line, specifying the x and y coordinates of the line and adding it to the canvas. In order to set the angle of a line object we use the angle property.

Syntax

new fabric.Line( points: Array , { angle: Number }: Object)

Parameters

points − This parameter accepts an Array of points which determines the (x1, y1) and (x2, y2) values, those being the x- and y-axis coordinates of the start and end of the line respectively.
options (optional) − This parameter is an Object which provides additional customizations to our Line object. Using this parameter stroke, corner colour, origin and a lot of other properties can be changed related to the Line object of which angle is a property.

Options Keys

angle − This property accepts a Number that determines the angle of rotation of an object in degrees.

Default appearance of Line object

Example

Let’s see a code example of how the Line object appears when the angle property is not used.


<!DOCTYPE html>
<html>
<head>
   <!-- Adding the Fabric JS Library-->
   <script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/510/fabric.min.js"></script>
</head>
<body>
   <h2>Default appearance of Line object</h2>
   <p>
      You can see the default appearance of line object
   </p>
   <canvas id="canvas"></canvas>
   <script>
      // Initiate a canvas instance
      var canvas = new fabric.Canvas("canvas");
      canvas.setWidth(document.body.scrollWidth);
      canvas.setHeight(250);

      // Initiate a Line object
      var line = new fabric.Line([200, 100, 100, 40], {
         stroke: "blue",
         strokeWidth: 20,
      });

      // Add it to the canvas
      canvas.add(line);
   </script>
</body>
</html>

Using the angle property

Example

In this example, we have used the angle property and assigned it a value of 60. This will make sure that our Line object has an angle of rotation of 60 degrees.


<!DOCTYPE html>
<html>
<head>
   <!-- Adding the Fabric JS Library-->
   <script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/510/fabric.min.js"></script>
</head>
<body>
   <h2>Using the angle property</h2>
   <p>
      You can see the angle of rotation is 60 degrees
   </p>
   <canvas id="canvas"></canvas>
   <script>
      // Initiate a canvas instance
      var canvas = new fabric.Canvas("canvas");
      canvas.setWidth(document.body.scrollWidth);
      canvas.setHeight(250);

      // Initiate a Line object
      var line = new fabric.Line([200, 100, 100, 40], {
         stroke: "blue",
         strokeWidth: 20,
         angle: 60
      });

      // Add it to the canvas
      canvas.add(line);
   </script>
</body>
</html>