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How to lock the rotation of Ellipse using FabricJS?
In this tutorial, we are going to learn how to lock the rotation of an Ellipse using FabricJS. Just as we can specify the position, color, opacity and dimension of an ellipse object in the canvas, we can also specify whether we want it to rotate or not. This can be done by using the lockRotation property.
Syntax
new fabric.Ellipse({ lockRotation : Boolean }: Object)
Parameters
-
options (optional) ? This parameter is an Object which provides additional customizations to our ellipse. Using this parameter color, cursor, stroke width and a lot of other properties can be changed related to the object of which lockRotation is a property.
Options Keys
-
lockRotation ? This property accepts a Boolean value. If we assign it a 'true' value, then the object rotation will be locked.
Example 1: Default Behavior (Rotation Enabled)
Let's take an example to understand the default behaviour of an ellipse object when lockRotation property is not used. By default, we are able to rotate an ellipse object anticlockwise or clockwise.
<!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>How to lock the rotation of Ellipse using FabricJS</h2>
<p>You can select the object and rotate it freely, as we have not used the <b>lockRotation</b> property. This is the default behavior.</p>
<canvas id="canvas"></canvas>
<script>
// Initiate a canvas instance
var canvas = new fabric.Canvas("canvas");
// Initiate an ellipse instance
var ellipse = new fabric.Ellipse({
left: 115,
top: 50,
fill: "white",
rx: 80,
ry: 50,
stroke: "black",
strokeWidth: 5,
});
// Adding it to the canvas
canvas.add(ellipse);
canvas.setWidth(document.body.scrollWidth);
canvas.setHeight(250);
</script>
</body>
</html>
Example 2: Rotation Locked with lockRotation Property
In this example, we will see how we can cease the ability of an ellipse object to rotate by using the lockRotation property. As we can see, as soon as we try to rotate the ellipse object, a not-allowed cursor is shown. This means that the rotation action is no longer allowed.
<!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>How to lock the rotation of Ellipse using FabricJS</h2>
<p>Here you can select the object but cannot rotate it freely, as we have set <b>lockRotation</b> to True.</p>
<canvas id="canvas"></canvas>
<script>
// Initiate a canvas instance
var canvas = new fabric.Canvas("canvas");
// Initiate an ellipse instance
var ellipse = new fabric.Ellipse({
left: 115,
top: 50,
fill: "white",
rx: 80,
ry: 50,
stroke: "black",
strokeWidth: 5,
lockRotation: true,
});
// Adding it to the canvas
canvas.add(ellipse);
canvas.setWidth(document.body.scrollWidth);
canvas.setHeight(250);
</script>
</body>
</html>
Key Points
The
lockRotationproperty is set tofalseby default, allowing free rotationWhen
lockRotation: trueis set, the rotation handles are disabled and a "not-allowed" cursor appearsOther object manipulations like moving and scaling remain unaffected by this property
Conclusion
The lockRotation property in FabricJS provides precise control over ellipse object interactions. Setting it to true prevents rotation while maintaining other transformation capabilities, making it useful for creating fixed-orientation elements in your canvas applications.
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