<?php 
/** 
*ImageCode 生成包含验证码的GIF图片的函数 
*@param $string 字符串 
*@param $width 宽度 
*@param $height 高度 
**/ 
function ImageCode($string='',$width=75,$height=25){ 
 $authstr=$string?$string:((time()%2==0)?mt_rand(1000,9999):mt_rand(10000,99999)); 
 $board_width=$width; 
 $board_height=$height; 
 // 生成一个32帧的GIF动画 
 for($i=0;$i<32;$i++){ 
  ob_start(); 
  $image=imagecreate($board_width,$board_height); 
  imagecolorallocate($image,0,0,0); 
  // 设定文字颜色数组 
  $colorList[]=ImageColorAllocate($image,15,73,210); 
  $colorList[]=ImageColorAllocate($image,0,64,0); 
  $colorList[]=ImageColorAllocate($image,0,0,64); 
  $colorList[]=ImageColorAllocate($image,0,128,128); 
  $colorList[]=ImageColorAllocate($image,27,52,47); 
  $colorList[]=ImageColorAllocate($image,51,0,102); 
  $colorList[]=ImageColorAllocate($image,0,0,145); 
  $colorList[]=ImageColorAllocate($image,0,0,113); 
  $colorList[]=ImageColorAllocate($image,0,51,51); 
  $colorList[]=ImageColorAllocate($image,158,180,35); 
  $colorList[]=ImageColorAllocate($image,59,59,59); 
  $colorList[]=ImageColorAllocate($image,0,0,0); 
  $colorList[]=ImageColorAllocate($image,1,128,180); 
  $colorList[]=ImageColorAllocate($image,0,153,51); 
  $colorList[]=ImageColorAllocate($image,60,131,1); 
  $colorList[]=ImageColorAllocate($image,0,0,0); 
  $fontcolor=ImageColorAllocate($image,0,0,0); 
  $gray=ImageColorAllocate($image,245,245,245); 
  $color=imagecolorallocate($image,255,255,255); 
  $color2=imagecolorallocate($image,255,0,0); 
  imagefill($image,0,0,$gray); 
  $space=15;// 字符间距 
  if($i>0){// 屏蔽第一帧 
   $top=0; 
   for($k=0;$k<strlen($authstr);$k++){ 
    $colorRandom=mt_rand(0,sizeof($colorList)-1); 
    $float_top=rand(0,4); 
    $float_left=rand(0,3); 
    imagestring($image,6,$space*$k,$top+$float_top,substr($authstr,$k,1),$colorList[$colorRandom]); 
   } 
  } 
  for($k=0;$k<20;$k++){ 
   $colorRandom=mt_rand(0,sizeof($colorList)-1); 
   imagesetpixel($image,rand()%70,rand()%15,$colorList[$colorRandom]); 
  
  } 
  // 添加干扰线 
  for($k=0;$k<3;$k++){ 
   $colorRandom=mt_rand(0,sizeof($colorList)-1); 
   $todrawline=1; 
   if($todrawline){ 
    imageline($image,mt_rand(0,$board_width),mt_rand(0,$board_height),mt_rand(0,$board_width),mt_rand(0,$board_height),$colorList[$colorRandom]); 
   }else{ 
    $w=mt_rand(0,$board_width); 
    $h=mt_rand(0,$board_width); 
    imagearc($image,$board_width-floor($w / 2),floor($h / 2),$w,$h, rand(90,180),rand(180,270),$colorList[$colorRandom]); 
   } 
  } 
  imagegif($image); 
  imagedestroy($image); 
  $imagedata[]=ob_get_contents(); 
  ob_clean(); 
  ++$i; 
 } 
 $gif=new GIFEncoder($imagedata); 
 Header('Content-type:image/gif'); 
 echo $gif->GetAnimation(); 
} 
 
 
/** 
*GIFEncoder类 
**/ 
Class GIFEncoder{ 
 var $GIF="GIF89a";    /* GIF header 6 bytes  */ 
 var $VER="GIFEncoder V2.06";  /* Encoder version   */ 
 var $BUF=Array(); 
 var $LOP=0; 
 var $DIS=2; 
 var $COL=-1; 
 var $IMG=-1; 
 var $ERR=Array( 
  'ERR00'=>"Does not supported function for only one image!", 
  'ERR01'=>"Source is not a GIF image!", 
  'ERR02'=>"Unintelligible flag ", 
  'ERR03'=>"Could not make animation from animated GIF source", 
 ); 
 function GIFEncoder($GIF_src,$GIF_dly=100,$GIF_lop=0,$GIF_dis=0, $GIF_red=0,$GIF_grn=0,$GIF_blu=0,$GIF_mod='bin'){ 
  if(!is_array($GIF_src)&&!is_array($GIF_tim)){ 
   printf("%s: %s",$this->VER,$this->ERR['ERR00']); 
   exit(0); 
  } 
  $this->LOP=($GIF_lop>-1)?$GIF_lop:0; 
  $this->DIS=($GIF_dis>-1)?(($GIF_dis<3)?$GIF_dis:3):2; 
  $this->COL=($GIF_red>-1&&$GIF_grn>-1&&$GIF_blu>-1)?($GIF_red |($GIF_grn<<8)|($GIF_blu<<16)):-1; 
 
  for($i=0,$src_count=count($GIF_src);$i<$src_count;$i++){ 
   if(strToLower($GIF_mod)=="url"){ 
    $this->BUF[]=fread(fopen($GIF_src [$i],"rb"),filesize($GIF_src [$i])); 
   }elseif(strToLower($GIF_mod)=="bin"){ 
    $this->BUF [ ]=$GIF_src [ $i ]; 
   }else{ 
    printf("%s: %s(%s)!",$this->VER,$this->ERR [ 'ERR02' ],$GIF_mod); 
    exit(0); 
   } 
   if(substr($this->BUF[$i],0,6)!="GIF87a"&&substr($this->BUF [$i],0,6)!="GIF89a"){ 
    printf("%s: %d %s",$this->VER,$i,$this->ERR ['ERR01']); 
    exit(0); 
   } 
   for($j=(13+3*(2<<(ord($this->BUF[$i]{10})&0x07))),$k=TRUE;$k;$j++){ 
    switch($this->BUF [$i]{$j}){ 
     case "!": 
      if((substr($this->BUF[$i],($j+3),8))=="NETSCAPE"){ 
        printf("%s: %s(%s source)!",$this->VER,$this->ERR ['ERR03'],($i+1)); 
        exit(0); 
      } 
      break; 
     case ";": 
      $k=FALSE; 
     break; 
    } 
   } 
  } 
  GIFEncoder::GIFAddHeader(); 
  for($i=0,$count_buf=count($this->BUF);$i<$count_buf;$i++){ 
   GIFEncoder::GIFAddFrames($i,$GIF_dly[$i]); 
  } 
  GIFEncoder::GIFAddFooter(); 
 } 
 function GIFAddHeader(){ 
  $cmap=0; 
  if(ord($this->BUF[0]{10})&0x80){ 
   $cmap=3*(2<<(ord($this->BUF [0]{10})&0x07)); 
   $this->GIF.=substr($this->BUF [0],6,7); 
   $this->GIF.=substr($this->BUF [0],13,$cmap); 
   $this->GIF.="!\377\13NETSCAPE2.0\3\1".GIFEncoder::GIFWord($this->LOP)."\0"; 
  } 
 } 
 function GIFAddFrames($i,$d){ 
  $Locals_str=13+3*(2 <<(ord($this->BUF[$i]{10})&0x07)); 
  $Locals_end=strlen($this->BUF[$i])-$Locals_str-1; 
  $Locals_tmp=substr($this->BUF[$i],$Locals_str,$Locals_end); 
  $Global_len=2<<(ord($this->BUF [0]{10})&0x07); 
  $Locals_len=2<<(ord($this->BUF[$i]{10})&0x07); 
  $Global_rgb=substr($this->BUF[0],13,3*(2<<(ord($this->BUF[0]{10})&0x07))); 
  $Locals_rgb=substr($this->BUF[$i],13,3*(2<<(ord($this->BUF[$i]{10})&0x07))); 
  $Locals_ext="!\xF9\x04".chr(($this->DIS<<2)+0).chr(($d>>0)&0xFF).chr(($d>>8)&0xFF)."\x0\x0"; 
  if($this->COL>-1&&ord($this->BUF[$i]{10})&0x80){ 
   for($j=0;$j<(2<<(ord($this->BUF[$i]{10})&0x07));$j++){ 
    if(ord($Locals_rgb{3*$j+0})==($this->COL>> 0)&0xFF&&ord($Locals_rgb{3*$j+1})==($this->COL>> 8)&0xFF&&ord($Locals_rgb{3*$j+2})==($this->COL>>16)&0xFF){ 
     $Locals_ext="!\xF9\x04".chr(($this->DIS<<2)+1).chr(($d>>0)&0xFF).chr(($d>>8)&0xFF).chr($j)."\x0"; 
     break; 
    } 
   } 
  } 
  switch($Locals_tmp{0}){ 
   case "!": 
    $Locals_img=substr($Locals_tmp,8,10); 
    $Locals_tmp=substr($Locals_tmp,18,strlen($Locals_tmp)-18); 
    break; 
   case ",": 
    $Locals_img=substr($Locals_tmp,0,10); 
    $Locals_tmp=substr($Locals_tmp,10,strlen($Locals_tmp)-10); 
    break; 
  } 
  if(ord($this->BUF[$i]{10})&0x80&&$this->IMG>-1){ 
   if($Global_len==$Locals_len){ 
    if(GIFEncoder::GIFBlockCompare($Global_rgb,$Locals_rgb,$Global_len)){ 
     $this->GIF.=($Locals_ext.$Locals_img.$Locals_tmp); 
    }else{ 
     $byte=ord($Locals_img{9}); 
     $byte|=0x80; 
     $byte&=0xF8; 
     $byte|=(ord($this->BUF [0]{10})&0x07); 
     $Locals_img{9}=chr($byte); 
     $this->GIF.=($Locals_ext.$Locals_img.$Locals_rgb.$Locals_tmp); 
    } 
   }else{ 
    $byte=ord($Locals_img{9}); 
    $byte|=0x80; 
    $byte&=0xF8; 
    $byte|=(ord($this->BUF[$i]{10})&0x07); 
    $Locals_img {9}=chr($byte); 
    $this->GIF.=($Locals_ext.$Locals_img.$Locals_rgb.$Locals_tmp); 
   } 
  }else{ 
   $this->GIF.=($Locals_ext.$Locals_img.$Locals_tmp); 
  } 
  $this->IMG=1; 
 } 
 function GIFAddFooter(){ 
  $this->GIF.=";"; 
 } 
 function GIFBlockCompare($GlobalBlock,$LocalBlock,$Len){ 
  for($i=0;$i<$Len;$i++){ 
   if($GlobalBlock{3*$i+0}!=$LocalBlock{3*$i+0}||$GlobalBlock{3*$i+1}!=$LocalBlock{3*$i+1}||$GlobalBlock{3*$i+2}!=$LocalBlock{3*$i+2}){ 
    return(0); 
   } 
  } 
  return(1); 
 } 
 function GIFWord($int){ 
  return(chr($int&0xFF).chr(($int>>8)&0xFF)); 
 } 
 function GetAnimation(){ 
  return($this->GIF); 
 } 
} 

/*调用示例*/ 
session_start(); 
$checkCode=''; 
$chars='abcdefghjkmnpqrstuvwxyzABCDEFGHJKLMNPRSTUVWXYZ23456789'; 
for($i=0;$i<4;$i++){ 
 $checkCode.=substr($chars,mt_rand(0,strlen($chars)-1),1); 
} 
$_SESSION['code']=strtoupper($checkCode);// 记录session 
ImageCode($checkCode,60);// 显示GIF动画