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How to lock the vertical movement of Ellipse using FabricJS?
In this tutorial, we are going to learn how to lock the vertical movement 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 move only in the X-axis. This can be done by using the lockMovementY property.
Syntax
new fabric.Ellipse({ lockMovementY: 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 lockMovementY is a property.
Options Keys
-
lockMovementY ? This property accepts a Boolean value. If we assign it a 'true' value, then the object will no longer be able to move in the vertical direction.
Example 1: Default Behavior
Default behaviour of an Ellipse object in the canvas
Let's see an example to understand how we can move our ellipse object freely in the Y-axis when the lockMovementY property is not assigned a "true" value.
<!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 vertical movement of Ellipse using FabricJS?</h2>
<p>Here you can select the object and move it freely as we have not applied the <b>lockMovementX</b> or <b>lockMovementY</b> property.</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: Locking Vertical Movement
Passing lockMovementY as key with 'true' value
In this example, we will see how we can lock the vertical movement of an Ellipse object. By assigning the lockMovementY property a "true" value, we essentially cease movement in the vertical direction.
<!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 vertical movement of Ellipse using FabricJS?</h2>
<p>Here you can select the object but we have locked its vertical movement by applying the <b>lockMovementY</b> property.</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,
lockMovementY: true,
});
// Adding it to the canvas
canvas.add(ellipse);
canvas.setWidth(document.body.scrollWidth);
canvas.setHeight(250);
</script>
</body>
</html>
Key Differences
| Property Value | Vertical Movement | Horizontal Movement |
|---|---|---|
| Default (false) | Allowed | Allowed |
| lockMovementY: true | Locked | Allowed |
Conclusion
The lockMovementY property in FabricJS provides precise control over ellipse movement by restricting vertical dragging while maintaining horizontal freedom. This is particularly useful for creating constrained user interfaces or guided interactions.
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