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How to lock the vertical scaling of Textbox using FabricJS?
In this tutorial, we are going to learn how to lock the vertical scaling of a Textbox using FabricJS. Just as we can specify the position, colour, opacity and dimension of a textbox 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.Textbox(text: String, { lockScalingY : Boolean }: Object)
Parameters
text ? This parameter accepts a String which is the text string that we want to display inside our textbox.
options (optional) ? This parameter is an Object which provides additional customizations to our textbox. 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 behaviour of a Textbox object in the canvas
Let's see a code example to understand the default behaviour of a Textbox 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 behaviour of a Textbox object in the canvas</h2>
<p>You can scale the textbox in horizontal and vertical directions to verify that scaling in both directions is possible</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 textbox object
var textbox = new fabric.Textbox("The fool wonders, the wise man asks.", {
width: 400,
left: 110,
top: 70,
fill: "violet",
strokeWidth: 2,
stroke: "pink",
textAlign: "center",
});
// Add it to the canvas
canvas.add(textbox);
</script>
</body>
</html>
Example 2: Passing lockScalingY as key with 'true' value
In this example, we will see how we can cease the ability of a Textbox object to scale vertically using the lockScalingY property. As we can see, although we can scale the textbox 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>Passing lockScalingY as key with "true" value</h2>
<p>You can see a not-allowed cursor if you try to scale the textbox in the y-direction</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 textbox object
var textbox = new fabric.Textbox("The fool wonders, the wise man asks.", {
width: 400,
left: 110,
top: 70,
fill: "violet",
strokeWidth: 2,
stroke: "pink",
textAlign: "center",
lockScalingY: true,
});
// Add it to the canvas
canvas.add(textbox);
</script>
</body>
</html>
How It Works
When lockScalingY is set to true, FabricJS disables the vertical scaling handles on the textbox. Users will see a "not-allowed" cursor when attempting to resize the object vertically, while horizontal scaling remains fully functional.
Conclusion
The lockScalingY property provides precise control over textbox scaling behavior in FabricJS. Use it when you need to maintain consistent text height while allowing width adjustments.
