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。

<?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); 
  }  
} 

php生成动态验证码用法示例：

/*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 

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。