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：