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。