本文实例讲述了JavaScript+html5 canvas制作色彩斑斓的正方形效果。分享给大家供大家参考，具体如下：
运行效果截图如下：
index.html：
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-type" content="text/html;charset=UTF-8" />
<title>canvas中的透明度</title>
<style type="text/css">
#canvas {
background:black; margin-top:100px; margin-left:200px;
}
</style>
</head>
<body>
<canvas id="canvas" width="500px" height="500px" ></canvas>
</body>
<script type="text/javascript" src="/UploadFiles/2021-04-02/canvas.js">
canvas.js：
(function() {
var dyl = {cache: {}};
dyl.setContext = function(context) {
dyl.cache._context = context;
return context;
};
dyl.getDom = function(id) {
return document.getElementById(id);
};
dyl._getContext = function() {
return dyl.cache._context;
};
dyl.save = function() {
var context = dyl._getContext();
context "2d"));
};
dyl.createColor = function() {
var color = "rgb(";
color += Math.round(Math.random()*255);
color += ",";
color += Math.round(Math.random()*255);
color += ",";
color += Math.round(Math.random()*255);
color += ")";
return color;
};
dyl.addImg = function(img, x, y) {
var context = dyl._getContext();
if(!img || !context) {
return;
}
if(typeof img === "string") {
var oImg = new Image();
oImg.src = img;
oImg.onload = function() {
context.drawImage(oImg, x, y);
}
return;
}
context.drawImage(img, x, y);
};
dyl.rect = function(color, x, y, width, height, alpha) {
var context = dyl._getContext();
if(!context) {
return;
}
context.save();
context.fillStyle = color;
context.globalAlpha = alpha "_blank" href="https://www.jb51.net/Special/104.htm">jQuery动画与特效用法总结》、《jQuery常见经典特效汇总》及《JavaScript动画特效与技巧汇总》
希望本文所述对大家JavaScript程序设计有所帮助。
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