Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
-
Economics & Finance
How to get the coordinates of a Line object using FabricJS?
In this tutorial, we are going to show how you can get the coordinates of a Line 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 get the coordinates of a Line object, we use the getCoords method.
Syntax
getCoords(): Array
Parameters
The getCoords method takes no parameters and returns an array containing four coordinate objects representing the corners of the line's bounding box.
Return Value
Returns an array of four objects, each containing x and y properties representing the top-left, top-right, bottom-right, and bottom-left coordinates of the line's bounding box.
Using getCoords Method
Let's see a code example to see the logged output when the getCoords method is used. The getCoords method returns the top-left, top-right, bottom-right and bottom-left coordinates of a Line in an array format.
<!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 getCoords method</h2>
<p>You can open console from dev tools and see the logged output</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([50, 100, 310, 100], {
stroke: "blue",
strokeWidth: 10,
});
// Add it to the canvas
canvas.add(line);
// Using getCoords method
console.log("The coordinates are: ", line.getCoords());
</script>
</body>
</html>
The coordinates are: [
{x: 45, y: 95},
{x: 315, y: 95},
{x: 315, y: 105},
{x: 45, y: 105}
]
Using getCoords Method for a Slant Line
In this example, we have used the getCoords method to obtain the coordinates of the Line instance with different starting and ending coordinates. We can see that the logged output shows the top-left, top-right, bottom-right and bottom-left coordinates of the line's bounding box.
<!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 getCoords method for a slant line</h2>
<p>You can open console from dev tools and see the logged output</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);
// Using getCoords method
console.log("The coordinates are: ", line.getCoords());
</script>
</body>
</html>
The coordinates are: [
{x: 90, y: 30},
{x: 210, y: 30},
{x: 210, y: 110},
{x: 90, y: 110}
]
Key Points
- The
getCoordsmethod returns the bounding box coordinates, not the actual line endpoints - The returned array always contains four coordinate objects in clockwise order
- For diagonal lines, the bounding box will be larger than the actual line area
- The coordinates include the stroke width in their calculations
Conclusion
The getCoords method in FabricJS provides an easy way to retrieve the bounding box coordinates of a Line object. This method is useful for collision detection, positioning calculations, and determining the spatial boundaries of line elements on the canvas.
942 Views
