HTMLcanvas rectangle shower-H5 Tutorial-php.cn

HTMLcanvas rectangle shower

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Release： 2017-05-28 10:40:48

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HTMLcanvasRectangle Shower

Execute on canvas
Get the drawing environment
Get full screen Screen Width and Screen Height
Determine the width of each text to determine the columns
LoopOutput
TimerCall

##HTML part

<!DOCTYPE HTML><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>HTMLcanvas矩形阵雨</title></head><body><canvas id="c">您的浏览器不支持 请升级</canvas></body></html>

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CSS Part

<style type="text/css">/* 基本的复位 */* {
    margin:0;
    padding:0;}/* 给body一个背景 使画布看起来更清晰 */body {
    background-color:#000;}canvas {
    display:block;}</style>

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##Javascript Part

<script type="text/jscript">
 var c = document.getElementById("c"); //获取id
 var ctx = c.getContext("2d"); //2d制图 
 c.width = window.innerWidth; //获取屏幕宽度 c.height = window.innerHeight; //获取屏幕高度
 
 var chinese = "abcdefghijklmnopqrstuvwxyz"; //canvas 阵雨文字 chinese = chinese.split(""); //split 分离
 
 var font_size = 10; //字体大小 10px
 var columns = c.width/font_size; 
 //获取列 屏幕宽度/字体大小
 var drops = []; // drop 落下 新建数组
 for(n=0; n < columns; n++) //控制列输出     drops[n] = 1; //draw
 function draw(){
     ctx.fillStyle = "rgba(0,0,0,0.05)"; //绘制矩形     ctx.fillRect(0,0,c.width,c.height); //以(0,0)为坐标 画制矩形     
     ctx.fillStyle = "#0F0"; //绿色字体     ctx.font = font_size + "px arial"; //以像素为单位 宋体
          
     for(var i=0; i< drops.length; i++)
     {         var text = chinese[Math.floor(Math.random()*chinese.length)];         // Math.floor 对浮点数向下取整         ctx.fillText(text, i*font_size, drops[i]*font_size);         // 规定在画布上输出的文本 开始绘制文本的x坐标 y坐标
         if(drops[i]*font_size > c.height && Math.random() > 0.975)         // 如果下落的文本大于屏幕高度 或者 随机数大于0.975             drops[i] = 0;         // 重置下落         drops[i]++;         // 继续执行     }
 }
 setInterval(draw,33); //33 执行一次draw()</script>

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