How to create a canvas with Triangle using FabricJS?


In this tutorial, we are going to learn about how to create a canvas with a Triangle object using FabricJS. Triangle is one of the various shapes provided by FabricJS. In order to create a triangle, we will have to create an instance of fabric.Triangle class and add it to the canvas.

Syntax

new fabric.Triangle({ width: Number, height: Number }: Object)

Parameters

  • Options (optional)− This parameter is an Object which provides additional customizations to our triangle. Using this parameter, properties such as colour, cursor, stroke width, and a lot of other properties can be changed related to the triangle object of which width and height are properties.

Options Keys

  • Width − This property accepts a Number which specifies the object's width. Its default value is 100.

  • Height − This property accepts a Number which specifies the object's height. Its default value is 100.

Example 1

Creating an instance of fabric.Triangle() and adding it to our canvas

Let's see a code example of how we can add a triangle to our canvas. Here we have created an object with a width of 100px and height of 70 px. Also, we have used the colour "orange" as a fill colour.

<!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>Creating an instance of fabric.Triangle() and adding it to our canvas</h2>
   <p>You can move around the triangle and interact with it</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 triangle object
      var triangle = new fabric.Triangle({
         left: 55,
         top: 60,
         width: 100,
         height: 70,
         fill: "orange",
      });

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

Example 2

Manipulating the Triangle object by using the set method

In this example, we have assigned the properties to the triangle by using the set method which is a setter for values. Any property related to stroke, strokeWidth, angle, scaling, rotation etc, can be mutated by using this method.

<!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>Manipulating the Triangle object by using the set method</h2>
   <p>You can move around the triangle and interact with it</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 triangle object
      var triangle = new fabric.Triangle();

      // Set the properties
      triangle.set("height", 70);
      triangle.set("width", 100);
      triangle.set("stroke", "#2a52be");
      triangle.set("strokeWidth", 5);
      triangle.set("fill", "#d9603b");
      triangle.set("top", 60);
      triangle.set("left", 55);

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

Updated on: 24-Jun-2022

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