php生成动态验证码gif图片

这是一个通过php生成的动态验证码图片的示例，重点是可以运行哦！下面先发下效果图：

下面是php生成动态验证码需要用到的相关类和函数。

0){// 屏蔽第一帧 
      $top=0; 
      for($k=0;$kGetAnimation(); 
} 
 
 
 
Class GIFEncoder{ 
  var $GIF="GIF89a";  
  var $VER="GIFEncoder V2.06";     
  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); 
      $this->GIF.="!37713NETSCAPE2.031".GIFEncoder::GIFWord($this->LOP).""; 
    }  
  }  
  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))); 
    $Locals_ext="!xF9x04".chr(($this->DIS<<2)+0).chr(($d>>0)&0xFF).chr(($d>>8)&0xFF)."x0x0"; 
    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){ 
   $Locals_ext="!xF9x04".chr(($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); 
  }  
} 

php生成动态验证码用法示例：

 
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 

以上就是php如何生成动态验证码的实现方法，希望对大家的学习有所帮助。