In this tutorial, we will learn how to set the opacity of a rectangle using FabricJS. Rectangle is one of the various shapes provided by FabricJS. in order to create a rectangle, we have to create an instance of the Fabric.Rect class and add it to
We can customize the rectangular object by adding a fill color, removing its borders, and even changing its dimensions. Likewise, we can also use the opacity property to change its opacity.
Syntax
new fabric.Rect({ opacity: Number }: Object)Parameters
Options (optional) - This parameter is an object which is our rectangle Provides additional customization. Using this parameter, you can change properties such as color, cursor, border width, and many other properties related to objects whose opacity is an attribute.
Option Key
opacity - This property accepts a Number which allows us to control The object's opacity. The default value of the opacity attribute is 1.
Example 1
Default Appearance of Rectangle Object
Let’s look at a code example and look at our rectangle object What does the opacity property look like at its default value. In this example we are not passing any opacity key to the class as shown below<!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 id="Default-appearance-of-a-rectangle-object">Default appearance of a rectangle object</h2>
<p>You can see our rectangle is fully opaque</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 rectangle object
var rect = new fabric.Rect({
left: 55,
top: 90,
width: 170,
height: 70,
fill: "#ffb347",
padding: 9,
stroke: "#191970",
strokeWidth: 5,
});
// Add it to the canvas
canvas.add(rect);
</script>
</body>
</html>Example 2
Pass the opacity property as key
In this example we will see how to assign the value opacity property changes The opacity of the rectangular object in the canvas. Here we use 0.3 as opacity As a result, our rectangular object appears semi-transparent rather than fully opaque.
<!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 id="Passing-the-opacity-property-as-key">Passing the opacity property as key</h2>
<p>You can see our rectangle is not fully opaque</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 rectangle object
var rect = new fabric.Rect({
left: 55,
top: 90,
width: 170,
height: 70,
fill: "#ffb347",
padding: 9,
stroke: "#191970",
strokeWidth: 5,
opacity: 0.3,
});
// Add it to the canvas
canvas.add(rect);
</script>
</body>
</html>The above is the detailed content of How to set opacity of rectangle using FabricJS?. For more information, please follow other related articles on the PHP Chinese website!
JavaScript Frameworks: Powering Modern Web DevelopmentMay 02, 2025 am 12:04 AMThe power of the JavaScript framework lies in simplifying development, improving user experience and application performance. When choosing a framework, consider: 1. Project size and complexity, 2. Team experience, 3. Ecosystem and community support.
The Relationship Between JavaScript, C , and BrowsersMay 01, 2025 am 12:06 AMIntroduction I know you may find it strange, what exactly does JavaScript, C and browser have to do? They seem to be unrelated, but in fact, they play a very important role in modern web development. Today we will discuss the close connection between these three. Through this article, you will learn how JavaScript runs in the browser, the role of C in the browser engine, and how they work together to drive rendering and interaction of web pages. We all know the relationship between JavaScript and browser. JavaScript is the core language of front-end development. It runs directly in the browser, making web pages vivid and interesting. Have you ever wondered why JavaScr
Node.js Streams with TypeScriptApr 30, 2025 am 08:22 AMNode.js excels at efficient I/O, largely thanks to streams. Streams process data incrementally, avoiding memory overload—ideal for large files, network tasks, and real-time applications. Combining streams with TypeScript's type safety creates a powe
Python vs. JavaScript: Performance and Efficiency ConsiderationsApr 30, 2025 am 12:08 AMThe differences in performance and efficiency between Python and JavaScript are mainly reflected in: 1) As an interpreted language, Python runs slowly but has high development efficiency and is suitable for rapid prototype development; 2) JavaScript is limited to single thread in the browser, but multi-threading and asynchronous I/O can be used to improve performance in Node.js, and both have advantages in actual projects.
The Origins of JavaScript: Exploring Its Implementation LanguageApr 29, 2025 am 12:51 AMJavaScript originated in 1995 and was created by Brandon Ike, and realized the language into C. 1.C language provides high performance and system-level programming capabilities for JavaScript. 2. JavaScript's memory management and performance optimization rely on C language. 3. The cross-platform feature of C language helps JavaScript run efficiently on different operating systems.
Behind the Scenes: What Language Powers JavaScript?Apr 28, 2025 am 12:01 AMJavaScript runs in browsers and Node.js environments and relies on the JavaScript engine to parse and execute code. 1) Generate abstract syntax tree (AST) in the parsing stage; 2) convert AST into bytecode or machine code in the compilation stage; 3) execute the compiled code in the execution stage.
The Future of Python and JavaScript: Trends and PredictionsApr 27, 2025 am 12:21 AMThe future trends of Python and JavaScript include: 1. Python will consolidate its position in the fields of scientific computing and AI, 2. JavaScript will promote the development of web technology, 3. Cross-platform development will become a hot topic, and 4. Performance optimization will be the focus. Both will continue to expand application scenarios in their respective fields and make more breakthroughs in performance.
Python vs. JavaScript: Development Environments and ToolsApr 26, 2025 am 12:09 AMBoth Python and JavaScript's choices in development environments are important. 1) Python's development environment includes PyCharm, JupyterNotebook and Anaconda, which are suitable for data science and rapid prototyping. 2) The development environment of JavaScript includes Node.js, VSCode and Webpack, which are suitable for front-end and back-end development. Choosing the right tools according to project needs can improve development efficiency and project success rate.
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
SecLists
SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.
SublimeText3 English version
Recommended: Win version, supports code prompts!
Zend Studio 13.0.1
Powerful PHP integrated development environment
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Notepad++7.3.1
Easy-to-use and free code editor
