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这篇文章主要介绍了php生成动态验证码gif图片的相关资料，需要的朋友可以参考下
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();
}
/**
*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)?(($GIF_disCOL=($GIF_red>-1&&$GIF_grn>-1&&$GIF_blu>-1)?($GIF_red |($GIF_grnBUF[]=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*(2BUF[$i]{10})&0x07))),$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);$iBUF[0]{10})&0x80){
$cmap=3*(2BUF [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){
$Locals_str=13+3*(2 BUF[$i]{10})&0x07));
$Locals_end=strlen($this->BUF[$i])-$Locals_str-1;
$Locals_tmp=substr($this->BUF[$i],$Locals_str,$Locals_end);
$Global_len=2BUF [0]{10})&0x07);
$Locals_len=2BUF[$i]{10})&0x07);
$Global_rgb=substr($this->BUF[0],13,3*(2BUF[0]{10})&0x07)));
$Locals_rgb=substr($this->BUF[$i],13,3*(2BUF[$i]{10})&0x07)));
$Locals_ext="!\xF9\x04".chr(($this->DIS>0)&0xFF).chr(($d>>8)&0xFF)."\x0\x0";
if($this->COL>-1&&ord($this->BUF[$i]{10})&0x80){
for($j=0;$jBUF[$i]{10})&0x07));$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>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>8)&0xFF));
}
function GetAnimation(){
return($this->GIF);
}
}
php生成动态验证码用法示例：