这篇文章主要介绍了PHP如何生成GIF动态图片验证码，在注册界面时大家经常用到验证码，需要了解的朋友可以参考下

这是一个用PHP生成GIF动画来实现动态图片验证码的程序，非常实用，是php用户注册登录界面经常需要用到的验证码程序，有需要GIF动态图片验证码功能的朋友可以收藏一下。
第一步：创建ImageCode.php文件，验证码生成函数代码如下：

0) // 屏蔽第一帧 { for ($k = 0; $k 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) ? (( $GIF_dis COL = ($GIF_red > -1 && $GIF_grn > -1 && $GIF_blu > -1) ? ($GIF_red | ($GIF_grn BUF[] = fread (fopen($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 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 BUF[0]{10}) & 0x80 ) { $cmap = 3 * ( 2 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 ) { $Locals_str = 13 + 3 * (2 BUF[$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 BUF [0]{10} ) & 0x07 ); $Locals_len = 2 BUF[$i]{10}) & 0x07); $Global_rgb = substr($this->BUF[0], 13, 3 * (2 BUF[0]{10} ) & 0x07))); $Locals_rgb = substr ( $this->BUF[$i], 13, 3 * (2 BUF[$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; $j BUF[$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 > 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); } }

第二步：验证码生成，创建yzimg.php，并引用入文件ImageCode.php。代码如下：