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FabricJS – How to scale an Image object to a given width?
In this tutorial, we are going to learn how to scale an Image object to a given width using FabricJS. We can create an Image object by creating an instance of fabric.Image. Since it is one of the basic elements of FabricJS, we can also easily customize it by applying properties like angle, opacity etc. In order to scale an Image object to a given width, we use the scaleToWidth method.
Syntax
scaleToWidth(value: Number, absolute: Boolean): fabric.Object
Parameters
value ? This parameter accepts a Number which determines the new width value of our Image object.
absolute ? This parameter accepts a Boolean value which determines whether the viewport is to be ignored or not.
Default Appearance of the Image Object
Let's see a code example to see how our image object looks when the scaleToWidth method is not used. In this case, our image object will not be scaled in horizontal or vertical directions.
<!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 appearance of the Image object</h2>
<p>
You can see that the object has not been scaled in horizontal or vertical direction
</p>
<canvas id="canvas"></canvas>
<img src="https://www.tutorialspoint.com/images/logo.png" id="img1" style="display: none" />
<script>
// Initiate a canvas instance
var canvas = new fabric.Canvas("canvas");
canvas.setWidth(document.body.scrollWidth);
canvas.setHeight(250);
// Initiating the image element
var imageElement = document.getElementById("img1");
// Initiate an Image object
var image = new fabric.Image(imageElement, {
top: 50,
left: 110,
});
// Add it to the canvas
canvas.add(image);
</script>
</body>
</html>
Using scaleToWidth Method with Custom Value
In this example, we will see how assigning a value to the scaleToWidth method scales our image object to a given width. Since we have passed the value as 200, that will be the new width of our image object.
<!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 the scaleToWidth method with a custom value</h2>
<p>You can see that the new width of our image object is 200</p>
<canvas id="canvas"></canvas>
<img src="https://www.tutorialspoint.com/images/logo.png" id="img1" style="display: none" />
<script>
// Initiate a canvas instance
var canvas = new fabric.Canvas("canvas");
canvas.setWidth(document.body.scrollWidth);
canvas.setHeight(250);
// Initiating the image element
var imageElement = document.getElementById("img1");
// Initiate an Image object
var image = new fabric.Image(imageElement, {
top: 50,
left: 110,
});
// Using the scaleToWidth method
image.scaleToWidth(200, false);
// Add it to the canvas
canvas.add(image);
</script>
</body>
</html>
Key Points
- The scaleToWidth method maintains the aspect ratio while scaling to the specified width
- The absolute parameter determines whether viewport transformations are considered
- Setting absolute to false means the viewport is taken into account during scaling
- This method returns the fabric object itself, allowing for method chaining
Conclusion
The scaleToWidth method in FabricJS provides an easy way to resize image objects while maintaining their aspect ratio. This method is particularly useful when you need to standardize image widths in your canvas applications.
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