88 lines
2.0 KiB
HTML
88 lines
2.0 KiB
HTML
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<!doctype html>
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<html>
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<head>
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<meta charset="utf-8" />
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<title>流星雨</title>
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<meta name="keywords" content="关键词，关键字">
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<meta name="description" content="描述信息">
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<style>
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body {
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margin: 0;
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overflow: hidden;
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}
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</style>
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</head>
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<body>
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<!--
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<canvas>画布 画板 画画的本子
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-->
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<canvas width=400 height=400 style="background:#000000;" id="canvas"></canvas>
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<!--
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javascript
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画笔
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-->
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<script>
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//获取画板
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//doccument 当前文档
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//getElement 获取一个标签
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//ById 通过Id名称的方式
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//var 声明一片空间
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//var canvas 声明一片空间的名字叫做canvas
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var canvas = document.getElementById("canvas");
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//获取画板权限 上下文
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var ctx = canvas.getContext("2d");
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//让画板的大小等于屏幕的大小
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/*
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思路：
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1.获取屏幕对象
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2.获取屏幕的尺寸
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3.屏幕的尺寸赋值给画板
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*/
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//获取屏幕对象
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var s = window.screen;
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//获取屏幕的宽度和高度
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var w = s.width;
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var h = s.height;
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//设置画板的大小
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canvas.width = w;
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canvas.height = h;
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//设置文字大小
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var fontSize = 14;
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//计算一行有多少个文字 取整数 向下取整
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var clos = Math.floor(w/fontSize);
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//思考每一个字的坐标
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//创建数组把clos 个 0 （y坐标存储起来）
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var drops = [];
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var str = "qwertyuiopasdfghjklzxcvbnm";
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//往数组里面添加 clos 个 0
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for(var i = 0;i<clos;i++) {
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drops.push(0);
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}
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//绘制文字
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function drawString() {
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//给矩形设置填充色
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ctx.fillStyle="rgba(0,0,0,0.05)"
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//绘制一个矩形
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ctx.fillRect(0,0,w,h);
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//添加文字样式
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ctx.font = "600 "+fontSize+"px 微软雅黑";
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//设置文字颜色
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ctx.fillStyle = "#00ff00";
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for(var i = 0;i<clos;i++) {
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//x坐标
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var x = i*fontSize;
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//y坐标
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var y = drops[i]*fontSize;
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//设置绘制文字
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ctx.fillText(str[Math.floor(Math.random()*str.length)],x,y);
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if(y>h&&Math.random()>0.99){
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drops[i] = 0;
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}
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drops[i]++;
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}
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}
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//定义一个定时器，每隔30毫秒执行一次
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setInterval(drawString,30);
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</script>
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</body>
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</html>
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