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How to lock the vertical scaling of a Circle using FabricJS?
In this tutorial, we are going to learn how to lock the vertical scaling of a Circle using FabricJS. Just as we can specify the position, colour, opacity and dimension of a circle object in the canvas, we can also specify whether we want to stop scaling an object vertically. This can be done by using the lockScalingY property.
Syntax
new fabric.Circle({ lockScalingY: Boolean })
Parameters
-
options (optional) ? This parameter is an Object which provides additional customizations to our circle. 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 lockScalingY is a property.
Options Keys
-
lockScalingY ? This property accepts a Boolean value. If we assign it a 'true' value, then the object's vertical scaling will be locked.
Example 1: Default Behavior
Default behaviour of a Circle object in the canvas
Let's see an example to understand the default behaviour of a Circle object when lockScalingY property is not used. Scaling the object in both horizontal and vertical directions is feasible.
<!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 scaling behavior of circle</h2>
<p>You can select the circle and scale it freely in any direction. This is the default behavior.</p>
<canvas id="canvas"></canvas>
<script>
// Initiate a canvas instance
var canvas = new fabric.Canvas("canvas");
var circle = new fabric.Circle({
left: 115,
top: 50,
fill: "white",
radius: 50,
stroke: "black",
strokeWidth: 5
});
// Adding it to the canvas
canvas.add(circle);
canvas.setWidth(document.body.scrollWidth);
canvas.setHeight(250);
</script>
</body>
</html>
Example 2: Locking Vertical Scaling
Passing lockScalingY as key with 'true' value
In this example, we will see how we can cease the ability of a circle object to scale vertically using the lockScalingY property. As we can see, although we can scale the circle object horizontally, we are not allowed to perform the same action vertically.
<!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>Locking the vertical scaling of circle using FabricJS</h2>
<p>Select the object and try to scale it by stretching its controlling corners. You will notice that the object can be scaled in the horizontal direction, but its vertical scaling is locked.</p>
<canvas id="canvas"></canvas>
<script>
// Initiate a canvas instance
var canvas = new fabric.Canvas("canvas");
var circle = new fabric.Circle({
left: 115,
top: 50,
fill: "white",
radius: 50,
stroke: "black",
strokeWidth: 5,
lockScalingY: true
});
// Adding it to the canvas
canvas.add(circle);
canvas.setWidth(document.body.scrollWidth);
canvas.setHeight(250);
</script>
</body>
</html>
Key Points
By default,
lockScalingYis set tofalse, allowing free scaling in all directionsSetting
lockScalingY: trueprevents vertical scaling while preserving horizontal scaling abilityThis property is useful when you want to maintain the height of an object while allowing width adjustments
Conclusion
The lockScalingY property provides precise control over object scaling behavior in FabricJS. Use it when you need to restrict vertical scaling while maintaining horizontal scaling flexibility for your circle objects.
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