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  • canvas画布,写字板

    <!doctype html>
    <html>
    <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
    <meta name="viewport" content="width=device-width">
    <meta name="description" content="">
    <meta name="keywords" content="">
    <style>
    *{margin:0;padding:0;}
    .out{
    800px;
    margin: 50px auto;
    position: relative;
    }
    .out p{
    font-size: 24px;
    color: red;
    position: absolute;
    top: 30px;
    left: 50%;
    transform: translateX(-50%);
    }
    .out button{
    color: green;
    font-style: 18px;
    cursor: pointer;
    position: absolute;
    top: 20px;
    right: 5%;
    border: none;
    background: none;
    outline: none;
    border: 1px solid green;
    padding: 2px 4px;
    border-radius: 2px;
    }
    #cvs1{
    background: #eee;
    cursor: pointer;
    }
    </style>
    </head>
    <body>
    <div class="out">
    <p>写写看...</p>
    <button>清除</button>
    <canvas id="cvs1" width="800" height="800"></canvas>
    </div>
    <script>
    var cvs=document.getElementById('cvs1'),
    ctx=cvs.getContext('2d'),
    l=cvs.getBoundingClientRect().left,
    t=cvs.getBoundingClientRect().top;

    ctx.beginPath();
    ctx.fillStyle="#eee";
    ctx.fillRect(0,0,800,800);
    ctx.closePath();

    cvs.onmousedown=function(ev){
    var ev=ev||window.event,
    x=ev.clientX-l,
    y=ev.clientY-t;

    ctx.beginPath();
    ctx.moveTo(x,y);

    document.onmousemove=function(ev){
    var ev=ev||window.event,
    dx=ev.clientX-l;
    dy=ev.clientY-t;

    ctx.lineTo(dx,dy);
    ctx.strokeStyle='red';
    ctx.lineWidth=4;
    ctx.stroke();
    return false;
    }
    document.onmouseup=function(){
    document.onmousedown=null;
    document.onmousemove=null;
    ctx.closePath();
    }
    return false;
    }

    document.getElementsByTagName('button')[0].onclick=function(){
    ctx.clearRect(0,0,800,800);
    }
    </script>
    </body>
    </html>

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  • 原文地址:https://www.cnblogs.com/luckyuns/p/6678824.html
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