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  • js预加载loading的canvas写法

    页面html:

    <!DOCTYPE html>
    <html>
    <head>
    <meta charset="UTF-8">
    <title>不需要页面图片显示加载</title>
    <style>
       html{
        background: gray;
       }
       #loading{
       z-index: 200;
       position: fixed;
       top: 50%;
       left: 50%;
       border:1px solid red;
    }
    #loading-screen {
       display: block;
       position: absolute;
       text-align: center;
        60px;
       height: 60px;
       top: 50%;
       -webkit-transform: translate(-50%,-50%);
       transform: translate(-50%,-50%);
       left: 50%;
       background: white;
       border-radius: 5px;
       z-index: 500;
    }
    #canvas-font-wrap{
        font-family: '微软雅黑';
        position:relative;
        height: 60px;
        60px;
        line-height: 60px;
        text-align: center;
        color: darkgray;
    }
    .font-center{
        height: 48px;
        48px;
        border:2px solid rgb(223,223,223);
        border-radius: 25px;
        line-height:48px;
        position: absolute;
        left: 4px;
        top:4px;
    }
    
    #loading-screen .vip-cvs {
       position: absolute;
       left: 0;
       top: 0;
       -webkit-transform: translate(-25%,-25%) scale(0.5);
       transform: translate(-25%,-25%) scale(0.5);
    }
    </style>
    </head>
    <body>
    <div id="loading">
       <div id='loading-screen'>
        <div id="canvas-font-wrap"style="">
        <div class="font-center" style="">cpp</div>
        </div>
           <canvas class='vip-cvs' width='120' height='120' id="canvas"></canvas>
       </div>
    </div>
    <!--//js路径更改自己的路径-->
    <script type="text/JavaScript" src="../js/jQuery.min.js" ></script>
    <!--js路径更改自己的路径-->
    <script type="text/javascript" src="../js/loadAnimation.js" ></script>
    <script type="text/javascript">
    showLoadingScreen();
    </script>
    </body>
    </html>
    

      

    页面加载打圈的js写法:

     1 /**
     2 
     3  * Created by chenxiaopeng on 2016/10/13.
     4  */
     5 var loadingHandel = null;
     6 function initLoadingAnimate() {
     7     var step = 0;
     8     var bg = $('.vip-cvs')[0];
     9     var ctx = bg.getContext('2d');
    10     var imd = null;
    11     var circ = Math.PI * 2;
    12     var quart = Math.PI / 2;
    13     var lineColor = '#e5007f';
    14     var backforward = true;
    15 
    16 
    17     ctx.clearRect(0, 0, 120, 120);
    18     ctx.beginPath();
    19     ctx.strokeStyle = lineColor;
    20     ctx.lineCap = 'square';
    21     ctx.closePath();
    22     ctx.fill();
    23     ctx.lineWidth = 2.8;
    24     imd = ctx.getImageData(0, 0, 120, 120);
    25     
    26     var draw = function(current) {
    27         ctx.putImageData(imd,0,0,0,0,120,120);
    28         ctx.beginPath();
    29         ctx.arc(60, 60, 50, -(quart), ((circ) * current) - quart, backforward);
    30         ctx.stroke();
    31     }
    32     function stepDraw() {
    33     //draw(0.5);
    34         step += 0.01;
    35         draw(step);
    36         if (step >= 0.99) {
    37             step = 0;
    38             if (!backforward) {
    39                 backforward = true;
    40             } else {
    41                 backforward = false;
    42             }
    43         }
    44     }
    45     loadingHandel = setInterval(stepDraw, 10);
    46 }
    47 
    48 function clearLoadingAnimation() {
    49     clearInterval(loadingHandel);
    50 }
    51 
    52 function showLoadingScreen() {
    53     initLoadingAnimate();
    54     $('#loading').show();
    55 }
    56 
    57 function hideLoadingScreen() {
    58     clearLoadingAnimation();
    59     $('#loading').hide();
    60 }

    //需要引进jquery,整个页面没有图片,很棒。

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  • 原文地址:https://www.cnblogs.com/viper-Demo/p/6004958.html
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