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How to lock the rotation of Rectangle using FabricJS?
In this tutorial, we are going to learn how to lock the rotation of a Rectangle using FabricJS. Just as we can specify the position, colour, opacity and dimension of a rectangle 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.Rect({ lockRotation : Boolean }: 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 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 Behaviour of Rectangle
Let's see a code example to understand the default behaviour of a rectangle object when lockRotation property is not used. By default, we are able to rotate a rectangle 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>Default behaviour of a Rectangle object in the canvas</h2>
<p>You can try rotating the rectangle to see the default behaviour</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: 55,
top: 90,
width: 170,
height: 70,
fill: "black",
padding: 9,
stroke: "#483d8b",
strokeWidth: 5,
});
// Add it to the canvas
canvas.add(rect);
</script>
</body>
</html>
Example 2: Using lockRotation Property
In this example, we will see how we can cease the ability of a rectangle object to rotate by using the lockRotation property. As we can see, as soon as we try to rotate the rectangle 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>Passing lockRotation as key with a True value</h2>
<p>Try rotating the object and you will see a not-allowed cursor on the rotate handle</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: 55,
top: 90,
width: 170,
height: 70,
fill: "black",
padding: 9,
stroke: "#483d8b",
strokeWidth: 5,
lockRotation: true,
});
// Add it to the canvas
canvas.add(rect);
</script>
</body>
</html>
Key Differences
| Property Value | Rotation Allowed | Cursor Behavior |
|---|---|---|
| Default (not specified) | Yes | Normal rotation cursor |
| lockRotation: true | No | Not-allowed cursor on rotate handle |
Conclusion
The lockRotation property in FabricJS provides precise control over rectangle rotation capabilities. Setting it to true prevents rotation and shows a not-allowed cursor, making it useful for creating fixed-orientation objects in your canvas applications.
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