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How to scale a Line object to a given width using FabricJS?
In this tutorial, we are going to learn how to scale a Line object to a given width using FabricJS. A Line element is one of the basic elements provided in FabricJS. It is used for creating straight lines. Because line elements are geometrically one-dimensional and do not contain an interior, they are never filled. We can create a line object by creating an instance of fabric.Line, specifying the x and y coordinates of the line and adding it to the canvas. In order to scale a Line 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 line object.
absolute ? This parameter accepts a Boolean value which determines whether the viewport is to be ignored or not.
Default appearance of the Line object
Let's see a code example to see how our line object looks when the scaleToWidth method is not used. In this case, our line 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 Line object</h2>
<p>
You can see that the object has not been scaled in horizontal or vertical 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 Line object
var line = new fabric.Line([200, 100, 100, 40], {
stroke: "blue",
strokeWidth: 20,
});
// Add it to the canvas
canvas.add(line);
</script>
</body>
</html>
Passing the scaleToWidth method with a custom value
In this example, we will see how assigning a value to the scaleToWidth method scales our line object to a given width. Since we have passed the value as 200, that will be the new width of our line 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 line object is 200
</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 Line object
var line = new fabric.Line([200, 100, 100, 40], {
stroke: "blue",
strokeWidth: 20,
});
// Using the scaleToWidth method
line.scaleToWidth(200, false);
// Add it to the canvas
canvas.add(line);
</script>
</body>
</html>
Key Points
- The
scaleToWidthmethod resizes the line object to match the specified width while maintaining proportions - The
absoluteparameter controls whether viewport transformations are considered during scaling - Line objects in FabricJS are defined by start and end coordinates: [x1, y1, x2, y2]
Conclusion
The scaleToWidth method provides a convenient way to resize Line objects in FabricJS to specific widths. This method maintains the line's proportions while adjusting its horizontal scale to match your requirements.
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