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How to create an Object representation of a Line object using FabricJS?
In this tutorial, we are going to learn about how to create an Object representation 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 create an Object representation of a Line object, we use the toObject method.
Syntax
toObject(propertiesToInclude: Array): fabric.Object
Parameters
-
propertiesToInclude? This parameter accepts an Array which contains any properties we might want to additionally include in the output. This parameter is optional.
Using the toObject method
Let's see a code example to see the logged output when the toObject method is used. In this case, an Object representation of the line instance will be returned.
<!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 toObject method</h2>
<p>
You can open console from dev tools and see that the logged output contains the Object representation of the line instance
</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 the toObject method
console.log("Object representation of the Line instance is: ", line.toObject());
</script>
</body>
</html>
Object representation of the Line instance is: {
type: "line",
version: "5.1.0",
originX: "left",
originY: "top",
left: 150,
top: 70,
width: 100,
height: 60,
fill: "rgb(0,0,0)",
stroke: "blue",
strokeWidth: 20,
x1: 200,
y1: 100,
x2: 100,
y2: 40
}
Using toObject method to add additional properties
Let's see a code example to see how we can include additional properties by using the toObject method. In this case, we have added a custom property called "PropertyName". We can pass the specific property to the fabric.Line instance as second argument in options object and pass same key to the toObject 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>Using toObject method to add additional properties</h2>
<p>
You can open console from dev tools and see that the logged output contains added property called PropertyName
</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 with PropertyName key
// passed in options object
var line = new fabric.Line([200, 100, 100, 40], {
stroke: "blue",
strokeWidth: 20,
PropertyName: "property",
});
// Add it to the canvas
canvas.add(line);
// Using the toObject method
console.log(
"Object representation of the Line instance is: ",
line.toObject(["PropertyName"])
);
</script>
</body>
</html>
Object representation of the Line instance is: {
type: "line",
version: "5.1.0",
originX: "left",
originY: "top",
left: 150,
top: 70,
width: 100,
height: 60,
fill: "rgb(0,0,0)",
stroke: "blue",
strokeWidth: 20,
x1: 200,
y1: 100,
x2: 100,
y2: 40,
PropertyName: "property"
}
Conclusion
The toObject method in FabricJS converts a Line object into its JSON representation, making it useful for serialization and data storage. Use the optional parameter to include custom properties in the output object.
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