动态折线图：实时动态数据可视化

<?php
       
        function line_stats_pic($value_y,$width,$high,$strong=1,$fix=0){
        //y值处理函数
        function line_point_y($num,$width,$high,$max_num_add,$min_num_add,$y_pxdensity){
          $return=$high-floor(($num-$min_num_add+$y_pxdensity)/(($max_num_add-$min_num_add)/$high));
          return $return;
        }
         
        //参数处理
        $allnum=sizeof($value_y);
        $max_num=max($value_y);              //最大值
        $min_num=min($value_y);              //最小值
        $limit_m=$max_num-$min_num;            //极差
        $max_num_add=$max_num+$limit_m*0.1;        //轴最大值
        $min_num_add=$min_num-$limit_m*0.1;        //轴最小值
        $limit=$max_num_add-$min_num_add;         //极差-坐标轴y
        $y_pxdensity=($max_num_add-$min_num_add)/$high;  //y轴密度
        $x_pxdensity=floor($width/$allnum);        //x轴密度
        reset($value_y);                 //将数组指针归零
        $i=0;
        foreach($value_y as $val){
          $point_y[$i]=line_point_y($val,$width,$high,$max_num_add,$min_num_add,$y_pxdensity);
          $i++;
        }
        $zero_y=line_point_y(0,$width,$high,$max_num_add,$min_num_add,$y_pxdensity);  //零点的y值
        $empty_size_x=(strlen($max_num) > strlen($min_num) ? strlen($max_num) : strlen($min_num))*5+3;          //左边空白
         
        //图片流开始
        header("Content-type:image/png");