PHP中动态显示签名和ip原理

<?php
//包含一个计数器，一个提醒语句，用户ip以及自己的广告图片。
//给浏览器发送头，说我是张图片
Header("Content-type: image/PNG");
//这里定义计数器，放到一个文件里的
$Visited=array();
if (!file_exists("Counter"))
{
for($i=0;$i<24;$i++)
$Visited[$i]=0;
$str=$Visited[0];
for($i=1;$i<24;$i++)
$str.=",$Visited[$i]";
$fp=fopen("Counter","w");
fputs($fp,$str);
fclose($fp);
}
else
{
$fp=fopen("Counter","r");
$str=trim(fgets($fp,100));
$Visited=explode(",",$str);
fclose($fp);
}
$Visited[date("G")]=intval($Visited[date("G")])+1;
$str=$Visited[0];
$max=intval($Visited[0]);
for($i=1;$i<24;$i++)
{
$str.=",$Visited[$i]";
if($max<=intval($Visited[$i]))
$max=intval($Visited[$i]);
}
$fp=fopen("Counter","w");
fputs($fp,$str);
fclose($fp);
$sum=0;
for($i=0;$i<24;$i++)
{
$sum+=$Visited[$i];
}
//计数器结束
//开始创建图片定义颜色字体等
$im = imagecreate(400,100);
$black = ImageColorAllocate($im, 0,0,0);
$white = ImageColorAllocate($im, 255,255,255);
$red = ImageColorAllocate($im, 255,0,0);
$blue = ImageColorAllocate($im, 0,0,255);
$font=5;
$maginx=20;
$maginy=20;
//定义ip和主机名，当然是用户端的
$ip = getenv('REMOTE_ADDR');
$host = gethostbyaddr($ip);
$today = getdate();
$wday = $today['wday'];
//提醒片断，是周末则好不是周末则提醒上课
if($wday==6 || $wday==0){
$tips = "enjoy the wonderful weekend!";
}else{
$tips = "you'd better go to school.";
}
if($wday ==1){
$wday = "Monday";
} elseif ($wday==2){
$wday="Tuesday";
} elseif ($wday==3){
$wday="Wednsday";
} elseif ($wday==4){
$wday="Thursday";
} elseif ($wday==5){
$wday="Friday";
} elseif ($wday==6){
$wday="Saturday";
} elseif ($wday==0){
$wday="Sunday";
}
//开始创建图像背景边框
imagefill($im,0,0,$black);
imagefilledrectangle ($im, 1, 1, 398, 98, $white);
//定义画笔
$style = array ($white,$white,$white,$white,$white,$white,$white,$white,$white,$red);
imagesetstyle ($im, $style);
//有个运动效果就用笔刷来刷了，相当于photoshop中的画笔工具也
//ads是我自己的广告图
$brush = imagecreatefrompng ("http://172.24.16.80/testpic/smile1.png");
$brush1 = imagecreatefrompng ("http://172.24.16.80/testpic/ads.png");
$w2 = imagecolorallocate($brush,255,255,255);
imagecolortransparent ($brush, $w2);
imagesetbrush ($im, $brush);
imageline ($im, 350,20,360,20, IMG_COLOR_STYLEDBRUSHED);
imagecopy ($im, $brush1, 270, 40, 0, 0, 119, 48);

//定义输出文字
imagestring($im,$font,$maginx,$maginy+20,"Your computer's named:{$host}",$red);
imagestring($im,$font,$maginx,$maginy,"Your IP Address is:{$ip}",$red);
imagestring($im,2,2,2,"Today is {$wday} and {$tips}",$blue);
imagestring($im,3,10,$maginy+40,"TotalRefreshTimesFromToday:$sum",$blue);

//图片结尾必然语句
ImagePNG($im);
ImageDestroy($im);
?>