The Image
API supported by Canvas is very powerful; we can directly load the image and display it on the Canvas, and we can also cut and splice the display as needed Any image part;
In addition, Canvas provides us with the function of storing its pixel data. We can manipulate the pixel data and then redraw it onto the Canvas.
Although Canvas only provides a few Image API functions, it opens up a world of pixel-level manipulation;
It enables developers to create optimized applications directly in the web browser without any plug-ins.
Canvas Api allows access to DOM-defined Image objects:
,
It also supports using javascript to create Image object instances: var img1=new Image();
Create image After that, you can set its path: img1.;
##When the Image is called in the code, we need to ensure that it can Being loaded and used; when the load event of the Image occurs, we can create a listening event to trigger the operation on the Image;
img1.addEventListener('load', eventLoaded, false);
When the Image is completely loaded, eventLoaded will be triggered to execute; in these events, we can execute the Image operation;
function eventLoaded() { drawScreen();//The main method entry for Image operation; }
Display Image (display image);
Method: drawImage(image,x,y):
image represents the image to be drawn;
(x,y) represents the position of the upper left corner of the image when the image is drawn on the Canvas;
Resize Image
Method: drawImage(image,x,y,width,height):
image represents the original image;
Resize the image according to the parameters [width, height] , forming NewImage;
(x,y) represents the position of the upper left corner of NewImage when NewImage is drawn on Canvas;
Get some parts of Image
drawImage(image, sx, sy, sw, sh, x, y, width, height)
image represents the original image;
Point (sx, xy) and [width sw, height sh] form a rectangle, which is an operation for image, take the original Part of the image forms a new partImage;
Adjust the size of the partImage according to the parameters [width, height] to form a NewImage;
(x,y) represents the position of the upper left corner of NewImage when NewImage is drawn on Canvas;
example instance:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Images</title>
<script type="text/javascript" src="../script/modernizr-latest.js"></script>
<script type="text/javascript">
window.addEventListener("load", eventWindowLoaded, false);
function eventWindowLoaded() {
canvasApp();
}
function canvasSupport() {
return Modernizr.canvas;
}
function eventWindowLoaded() {
canvasApp();
}
function canvasApp() {
if(!canvasSupport()) {
return;
}
var theCanvas = document.getElementById("canvasOne");
var context = theCanvas.getContext("2d");
var imgmain = new Image();
imgmain.addEventListener('load', eventLoaded, false);
imgmain.src = "image.png";
function eventLoaded() {
drawScreen();
}
function drawScreen() {
context.fillStyle = "#EEEEEE";
context.fillRect(0, 0, theCanvas.width, theCanvas.height)
//display image107*86
context.drawImage(imgmain, 0, 0);
context.drawImage(imgmain, 120, 0);
//resize image
context.drawImage(imgmain, 0, 90, 107, 86);
context.drawImage(imgmain, 120, 90, 53, 43);
context.drawImage(imgmain, 190, 90, 26, 21);
//part of image
context.drawImage(imgmain, 0, 0, 107, 86, 0, 180, 107, 86);
context.drawImage(imgmain, 0, 0, 57, 86, 120, 180, 57, 86);
context.drawImage(imgmain, 50, 0, 57, 86, 190, 180, 57, 86);
context.drawImage(imgmain, 0, 0, 57, 43, 260, 180, 57, 43);
context.drawImage(imgmain, 50, 43, 57, 43, 330, 223, 57, 43);
}
}
</script>
</head>
<body>
<div style="position: absolute; top: 50px; left: 50px;">
<canvas id="canvasOne" width="500" height="300">
Your browser does not support HTML5 Canvas.
</canvas>
</div>
</body>
</html>Pictures cited in the example:
Example renderings:
The above is the detailed content of Detailed explanation of graphic code of Html5 Canvas Image (1). For more information, please follow other related articles on the PHP Chinese website!
html5的div一行可以放两个吗Apr 25, 2022 pm 05:32 PMhtml5的div元素默认一行不可以放两个。div是一个块级元素，一个元素会独占一行，两个div默认无法在同一行显示；但可以通过给div元素添加“display：inline;”样式，将其转为行内元素，就可以实现多个div在同一行显示了。
html5中列表和表格的区别是什么Apr 28, 2022 pm 01:58 PMhtml5中列表和表格的区别：1、表格主要是用于显示数据的，而列表主要是用于给数据进行布局；2、表格是使用table标签配合tr、td、th等标签进行定义的，列表是利用li标签配合ol、ul等标签进行定义的。
html5怎么让头和尾固定不动Apr 25, 2022 pm 02:30 PM固定方法：1、使用header标签定义文档头部内容，并添加“position:fixed;top:0;”样式让其固定不动；2、使用footer标签定义尾部内容，并添加“position: fixed;bottom: 0;”样式让其固定不动。
HTML5中画布标签是什么May 18, 2022 pm 04:55 PMHTML5中画布标签是“<canvas>”。canvas标签用于图形的绘制，它只是一个矩形的图形容器，绘制图形必须通过脚本（通常是JavaScript）来完成；开发者可利用多种js方法来在canvas中绘制路径、盒、圆、字符以及添加图像等。
html5中不支持的标签有哪些Mar 17, 2022 pm 05:43 PMhtml5中不支持的标签有：1、acronym，用于定义首字母缩写，可用abbr替代；2、basefont，可利用css样式替代；3、applet，可用object替代；4、dir，定义目录列表，可用ul替代；5、big，定义大号文本等等。
html5废弃了哪个列表标签Jun 01, 2022 pm 06:32 PMhtml5废弃了dir列表标签。dir标签被用来定义目录列表，一般和li标签配合使用，在dir标签对中通过li标签来设置列表项，语法“<dir><li>列表项值</li>...</dir>”。HTML5已经不支持dir，可使用ul标签取代。
Html5怎么取消td边框May 18, 2022 pm 06:57 PM3种取消方法：1、给td元素添加“border:none”无边框样式即可，语法“td{border:none}”。2、给td元素添加“border:0”样式，语法“td{border:0;}”，将td边框的宽度设置为0即可。3、给td元素添加“border:transparent”样式，语法“td{border:transparent;}”，将td边框的颜色设置为透明即可。
html5是什么意思Apr 26, 2021 pm 03:02 PMhtml5是指超文本标记语言（HTML）的第五次重大修改，即第5代HTML。HTML5是Web中核心语言HTML的规范，用户使用任何手段进行网页浏览时看到的内容原本都是HTML格式的，在浏览器中通过一些技术处理将其转换成为了可识别的信息。HTML5由不同的技术构成，其在互联网中得到了非常广泛的应用，提供更多增强网络应用的标准机。
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
SublimeText3 English version
Recommended: Win version, supports code prompts!
Safe Exam Browser
Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.
Zend Studio 13.0.1
Powerful PHP integrated development environment
DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software
mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),
