How to create a Rectangle with border colour using FabricJS?


In this tutorial, we are going to create a Rectangle with border colour using FabricJS. Rectangle is one of the various shapes provided by FabricJS. In order to create a rectangle, we will have to create an instance of fabric.Rect class and add it to the canvas.

Since FabricJS is extremely flexible, we are allowed to customize our rectangle object in any way we like. One of the properties that FabricJS provides is borderColor which allows us to manipulate the colour of the border when our object is active.

Syntax

new fabric.Rect({ borderColor: String }: Object)

Parameters

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

Options Keys

  • borderColor − This property accepts a String which specifies the colour of the border when our rectangle object is selected. Its default value is rgb(178,204,255).

Example 1

Passing borderColour key with a String value 

Let’s see a code example of how we can assign a value to the borderColor property. We have assigned the value "blue" to the borderColor key which helps to create the blue border on selection of our rectangle object.

<!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>Passing borderColour key with a String value</h2>
   <p>Select the rectangle to see the border colour</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 rectangle object
      var rect = new fabric.Rect({
         left: 125,
         top: 90,
         width: 170,
         height: 70,
         fill: "#cf1020",
         borderColor: "blue",
         padding: 9,
      });

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

Example 2

Passing an RGBA value to the borderColor key

Instead of passing simple colour names as a String, we can also use RGBA values, whose components specify the amount of Red, Green, Blue and Alpha, where alpha denotes the opacity. In this example, we have used rgb(128,0,128) which is the rgb value for the colour purple.

<!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>Passing an RGBA value to the borderColor key</h2>
   <p>Select the rectangle to see the border colour</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 rectangle object
      var rect = new fabric.Rect({
         left: 125,
         top: 90,
         width: 170,
         height: 70,
         fill: "#cf1020",
         borderColor: "rgb(128,0,128)",
         padding: 9,
      });

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

Updated on: 28-Jun-2022

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