今天写动态canvas柱状图小结

时间：2022-05-22 03:59:16
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #main{
            margin-top:100px;
            text-align: center;
        }
        #c1{
            background: pink;
        }
    </style>
</head>
<body>
<div id="main">
    <canvas ID="c1" width="600" height="600"></canvas>

</div>
<script src="jquery-1.11.3.js"></script>
<script>
var ctx=c1.getContext("2d");

var arr=[0,0,0,0,0,0];
    $.ajax(
            {
                type:'get',
                url:"1.php",
                success:function(result){
                    console.log(typeof  result);
                  result= JSON.parse(result);
                    console.log(result);
                    ctx.font="20px  SimHei";

                           var timer=setInterval( function(){
                               paint(result,0);
                               paint(result,1);
                               paint(result,2);
                               paint(result,3);
                               paint(result,4);
                               paint(result,5);

                           },41);

                },
                error:function(){
                    console.log("失败");
                }
            }
    );

function paint(result,i){

    var g=ctx.createLinearGradient(0,0,600,600);
    g.addColorStop(0,"#f00");
    g.addColorStop(0.5,"#ff0");
    g.addColorStop(1,"#83ED4D");
    ctx.fillStyle=g;
    arr[i]+=10;因为要在一个定时器同时画6个柱状图，每次定时器还要保存上一次的数据因此用一个数组来存放6各数据
    if(arr[i]>result[i].value)
    {
        arr[i]=result[i].value;
    }
    ctx.fillRect(60*(i+1),570-arr[i],20,arr[i]);

    ctx.fillStyle='#000';
    var xtext=60*(i+1)-ctx.measureText(result[i].label).width/2+8;
    ctx.fillText(result[i].label,xtext,590);
}
</script>
</body>
</html>

1.php


<?php
/**
 * Created by PhpStorm.
 * User: Administrator
 * Date: 2016/12/10
 * Time: 9:22
 */
header("Content-Type:application/json");

$arr='[
   {"label": "部门1", "value":300},
   {"label": "部门2", "value":500},
   {"label": "部门3", "value":150},
   {"label": "部门4", "value":400},
   {"label": "部门5", "value":550},
   {"label": "部门6", "value":250}
]';
echo json_encode($arr);

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