Web Front-end
JS Tutorial
js draws two intersecting rectangles and one of them contains transparency
js draws two intersecting rectangles and one of them contains transparency
Hello~ Today I will introduce to you how to draw two intersecting rectangles through javascript and one of them has alpha transparency. Doesn’t it seem a bit unclear at first glance? Let’s take a look at the rendering below and you’ll see clearly at a glance!
As shown in the picture:
Understand it~
That is to say, we now need to write a javascript program to achieve such a Renderings, do you have any ideas?
Haha, no nonsense, let’s get straight to the point.
Above code:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>js绘制两个相交的矩形并且其中有一个包含透明度</title>
</head>
<body onload="draw();">
<canvas id="canvas" width="150" height="150"></canvas>
<script>
function draw()
{
var canvas = document.getElementById("canvas");
if (canvas.getContext)
{
var context = canvas.getContext("2d");
context.fillStyle = "rgb(256,0,0)";
context.fillRect (15, 10, 55, 50);
context.fillStyle = "rgba(0, 0, 200, 0.6)";
context.fillRect (35, 30, 55, 50);
}
}
</script>
</body>
</html>You can directly copy this code to run locally for testing. The effect is the same as the picture above.
So regarding the above code, we introduce several important knowledge points:
1. getElementById() method can return the first object with the specified ID. Quote.
2, Body onload event, the onload event is triggered immediately after the page is loaded. Note: All major browsers support the onload event.
3, <canvas></canvas> tag defines graphics, such as charts and other images. Note: Internet Explorer 8 or earlier does not support the
4, fillStyle Property sets or returns the color, gradient, or pattern used to fill the painting. The default value is #000000; its js syntax is "context.fillStyle=color|gradient|pattern;".
5, fillRect() method draws a "filled" rectangle. The default fill color is black; its js syntax is "context.fillRect(x,y,width,height);".
Finally, I would like to recommend the classic course "JavaScript Quick Introduction_Jade Girl Heart Sutra Series" on this platform to everyone. It is free for public welfare ~ everyone is welcome to learn ~
The above is the detailed content of js draws two intersecting rectangles and one of them contains transparency. For more information, please follow other related articles on the PHP Chinese website!
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
AI Hentai Generator
Generate AI Hentai for free.
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
1378
52
How to implement an online speech recognition system using WebSocket and JavaScript
Dec 17, 2023 pm 02:54 PM
How to use WebSocket and JavaScript to implement an online speech recognition system Introduction: With the continuous development of technology, speech recognition technology has become an important part of the field of artificial intelligence. The online speech recognition system based on WebSocket and JavaScript has the characteristics of low latency, real-time and cross-platform, and has become a widely used solution. This article will introduce how to use WebSocket and JavaScript to implement an online speech recognition system.
WebSocket and JavaScript: key technologies for implementing real-time monitoring systems
Dec 17, 2023 pm 05:30 PM
WebSocket and JavaScript: Key technologies for realizing real-time monitoring systems Introduction: With the rapid development of Internet technology, real-time monitoring systems have been widely used in various fields. One of the key technologies to achieve real-time monitoring is the combination of WebSocket and JavaScript. This article will introduce the application of WebSocket and JavaScript in real-time monitoring systems, give code examples, and explain their implementation principles in detail. 1. WebSocket technology
How to use JavaScript and WebSocket to implement a real-time online ordering system
Dec 17, 2023 pm 12:09 PM
Introduction to how to use JavaScript and WebSocket to implement a real-time online ordering system: With the popularity of the Internet and the advancement of technology, more and more restaurants have begun to provide online ordering services. In order to implement a real-time online ordering system, we can use JavaScript and WebSocket technology. WebSocket is a full-duplex communication protocol based on the TCP protocol, which can realize real-time two-way communication between the client and the server. In the real-time online ordering system, when the user selects dishes and places an order
How to implement an online reservation system using WebSocket and JavaScript
Dec 17, 2023 am 09:39 AM
How to use WebSocket and JavaScript to implement an online reservation system. In today's digital era, more and more businesses and services need to provide online reservation functions. It is crucial to implement an efficient and real-time online reservation system. This article will introduce how to use WebSocket and JavaScript to implement an online reservation system, and provide specific code examples. 1. What is WebSocket? WebSocket is a full-duplex method on a single TCP connection.
JavaScript and WebSocket: Building an efficient real-time weather forecasting system
Dec 17, 2023 pm 05:13 PM
JavaScript and WebSocket: Building an efficient real-time weather forecast system Introduction: Today, the accuracy of weather forecasts is of great significance to daily life and decision-making. As technology develops, we can provide more accurate and reliable weather forecasts by obtaining weather data in real time. In this article, we will learn how to use JavaScript and WebSocket technology to build an efficient real-time weather forecast system. This article will demonstrate the implementation process through specific code examples. We
Simple JavaScript Tutorial: How to Get HTTP Status Code
Jan 05, 2024 pm 06:08 PM
JavaScript tutorial: How to get HTTP status code, specific code examples are required. Preface: In web development, data interaction with the server is often involved. When communicating with the server, we often need to obtain the returned HTTP status code to determine whether the operation is successful, and perform corresponding processing based on different status codes. This article will teach you how to use JavaScript to obtain HTTP status codes and provide some practical code examples. Using XMLHttpRequest
How to use insertBefore in javascript
Nov 24, 2023 am 11:56 AM
Usage: In JavaScript, the insertBefore() method is used to insert a new node in the DOM tree. This method requires two parameters: the new node to be inserted and the reference node (that is, the node where the new node will be inserted).
JavaScript and WebSocket: Building an efficient real-time image processing system
Dec 17, 2023 am 08:41 AM
JavaScript is a programming language widely used in web development, while WebSocket is a network protocol used for real-time communication. Combining the powerful functions of the two, we can create an efficient real-time image processing system. This article will introduce how to implement this system using JavaScript and WebSocket, and provide specific code examples. First, we need to clarify the requirements and goals of the real-time image processing system. Suppose we have a camera device that can collect real-time image data
