html、canvas、视频灰度、反色_html/css_WEB-ITnose-HTML Tutorial-php.cn

Home

Web Front-end

HTML Tutorial

html、canvas、视频灰度、反色_html/css_WEB-ITnose

WBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWB

Jun 24, 2016 am 11:23 AM

效果图：

代码：

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title>canvas 视频颜色灰度化，反色</title>    <style type="text/css">       *{           margin: 0;           padding: 0;       }       #wrap{           border: 1px solid #ccc;       }       #sourcevid{           width: 400px;           height: 400px;           border: 1px solid #ccc;       }    </style></head><body>      <video id="sourcevid" autoplay="true" loop="true" width="400" height="400">        <source src="vodeo/daxiongtui(1).mp4" type="video/mp4"/>        <source src="vodeo/daxiongtui.ogv" type="video/ogg"/>    </video>    <canvas id="wrap" width="400" height="400">你的浏览器不支持canvas！</canvas>    <script type="text/javascript">          //获取id          var canvas = document.getElementById("wrap");          var ctx = canvas.getContext("2d");          var sourcevid = document.getElementById("sourcevid");                    sourcevid.oncanplaythrough = function() {                        function play() {                //在画布里绘制出sourcevid                ctx.drawImage(sourcevid,0,0);                                //反色                //getImageData() 复制画布上指定矩形的像素数据                //getImageData() 方法返回 ImageData 对象，该对象拷贝了画布指定矩形的像素数据。                //对于 ImageData 对象中的每个像素，都存在着四方面的信息，即 RGBA 值：                //R - 红色 (0-255)                //G - 绿色 (0-255)                //B - 蓝色 (0-255)                //A - alpha 通道 (0-255; 0 是透明的，255 是完全可见的)                //color/alpha 以数组形式存在，并存储于 ImageData 对象的 data 属性中。                                var imageData = ctx.getImageData(0,0,200,400);                var t = imageData.data;                for(var i = 0 ; i < t.length; i += 4) {                    t[i] = 255 - t[i];                    t[i+1] = 255 - t[i+1];                    t[i+2] = 255 - t[i+2];                    // t[i+3] = 255;                }                // putImageData() 将图像数据放回画布                ctx.putImageData(imageData,200,0);                                //灰度                var imageData = ctx.getImageData(0,0,200,400);                    var d = imageData.data;//保存的是红绿蓝透明度的通道的值                    //console.log(imageData);                for(var i = 0; i < d.length; i += 4) {                    //var verage = (d[i] + d[i+1] + d[i+2])/3;                    var verage1 = 0.299 * d[i] + 0.587 * d[i+1] + 0.114 * d[i+2]                    d[i] = d[i+1] = d[i+2] = verage1;                }                ctx.putImageData(imageData,0,0);                                window.requestAnimationFrame(play);            }            play();        }    </script></body></html>

注：本例需在服务器上运行的才能看到效果、视频文件可换成本地视频（HBuilder有集成服务器或者使用wampmanager亦可）

Statement

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

HTML: Building the Structure of Web PagesApr 14, 2025 am 12:14 AM

HTML is the cornerstone of building web page structure. 1. HTML defines the content structure and semantics, and uses, etc. tags. 2. Provide semantic markers, such as, etc., to improve SEO effect. 3. To realize user interaction through tags, pay attention to form verification. 4. Use advanced elements such as, combined with JavaScript to achieve dynamic effects. 5. Common errors include unclosed labels and unquoted attribute values, and verification tools are required. 6. Optimization strategies include reducing HTTP requests, compressing HTML, using semantic tags, etc.

From Text to Websites: The Power of HTMLApr 13, 2025 am 12:07 AM

HTML is a language used to build web pages, defining web page structure and content through tags and attributes. 1) HTML organizes document structure through tags, such as,. 2) The browser parses HTML to build the DOM and renders the web page. 3) New features of HTML5, such as, enhance multimedia functions. 4) Common errors include unclosed labels and unquoted attribute values. 5) Optimization suggestions include using semantic tags and reducing file size.

Understanding HTML, CSS, and JavaScript: A Beginner's GuideApr 12, 2025 am 12:02 AM

WebdevelopmentreliesonHTML,CSS,andJavaScript:1)HTMLstructurescontent,2)CSSstylesit,and3)JavaScriptaddsinteractivity,formingthebasisofmodernwebexperiences.

The Role of HTML: Structuring Web ContentApr 11, 2025 am 12:12 AM

The role of HTML is to define the structure and content of a web page through tags and attributes. 1. HTML organizes content through tags such as , making it easy to read and understand. 2. Use semantic tags such as, etc. to enhance accessibility and SEO. 3. Optimizing HTML code can improve web page loading speed and user experience.

HTML and Code: A Closer Look at the TerminologyApr 10, 2025 am 09:28 AM

HTMLisaspecifictypeofcodefocusedonstructuringwebcontent,while"code"broadlyincludeslanguageslikeJavaScriptandPythonforfunctionality.1)HTMLdefineswebpagestructureusingtags.2)"Code"encompassesawiderrangeoflanguagesforlogicandinteract

HTML, CSS, and JavaScript: Essential Tools for Web DevelopersApr 09, 2025 am 12:12 AM

HTML, CSS and JavaScript are the three pillars of web development. 1. HTML defines the web page structure and uses tags such as, etc. 2. CSS controls the web page style, using selectors and attributes such as color, font-size, etc. 3. JavaScript realizes dynamic effects and interaction, through event monitoring and DOM operations.

The Roles of HTML, CSS, and JavaScript: Core ResponsibilitiesApr 08, 2025 pm 07:05 PM

HTML defines the web structure, CSS is responsible for style and layout, and JavaScript gives dynamic interaction. The three perform their duties in web development and jointly build a colorful website.

Is HTML easy to learn for beginners?Apr 07, 2025 am 12:11 AM

HTML is suitable for beginners because it is simple and easy to learn and can quickly see results. 1) The learning curve of HTML is smooth and easy to get started. 2) Just master the basic tags to start creating web pages. 3) High flexibility and can be used in combination with CSS and JavaScript. 4) Rich learning resources and modern tools support the learning process.

See all articles