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How to crop the top offset in a cloned image using FabricJS?
In this tutorial, we are going to learn how to crop the top offset in a cloned image 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 crop the top offset in a cloned image, we use the top property.
Syntax
cloneAsImage( callback: function, { top: Number}: Object): fabric.Object
Parameters
callback (optional) ? This parameter is a function which is to be invoked with a cloned image instance as the first argument.
options (optional) ? This parameter is an optional Object which provides additional customizations to our clone image. Using this parameter we can set a multiplier, crop the clone image, remove the current object transform or a lot of properties can be changed of which top is a property.
Options Keys
top ? This property accepts a Number value which denotes top offset that has to be cropped. This property is optional.
Without using the top property
Let's see a code example of how the cloned Image object appears when the top property is not used. In this case, the cloned image will not be cropped.
<!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>Without using the top property</h2>
<p>You can see that no cropping has been applied to the clone image</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 a shadow object
var shadow = new fabric.Shadow({
color: "#308080",
blur: 3,
});
// Initiate an Image object
var image = new fabric.Image(imageElement, {
top: 50,
left: 110,
skewX: 20,
shadow: shadow,
});
// Using cloneAsImage method
image.cloneAsImage(function(Img) {
Img.set("top", 90);
canvas.add(Img);
});
</script>
</body>
</html>
Using the top property
In this example, we have used the top property and passed it a value 30 which is the cropping top offset for the clone image. Therefore, the top portion will be cropped.
<!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>Using the top property</h2>
<p>You can see that cropping has been applied to the clone image</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 a shadow object
var shadow = new fabric.Shadow({
color: "#308080",
blur: 3,
});
// Initiate an Image object
var image = new fabric.Image(imageElement, {
top: 50,
left: 110,
skewX: 20,
shadow: shadow,
});
// Using cloneAsImage method
image.cloneAsImage(
function(Img) {
Img.set("top", 150);
canvas.add(Img);
}, {
top: 30,
}
);
</script>
</body>
</html>
Key Points
- The
cloneAsImage()method creates a copy of the image object as a static image - The
topproperty in the options parameter crops pixels from the top of the cloned image - Higher
topvalues will crop more pixels from the top portion of the image - The original image object remains unchanged when cloning
Conclusion
In this tutorial, we used two examples to demonstrate how you can crop the top offset in a cloned image using FabricJS. The top property provides precise control over image cropping during the cloning process.
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