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：

<?php/** * ImageCode 生成GIF图片验证 * @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 { 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 = rand(0,1); $todrawline = 1; if($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"; var $VER = "GIFEncoder V2.06"; 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); } }

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

<?phpif(!isset($_SESSION)){ session_start();}require_once(dirname(__FILE__)."ImageCode.php");unset($_SESSION['yzm']);$randCode = '';$chars = 'abcdefghjkmnpqrstuvwxyzABCDEFGHJKLMNPRSTUVWXYZ23456789';for ( $i = 0; $i < 4; $i++ ){ $randCode .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);}$_SESSION['yzm']=$randCode; // 记录sessionImageCode($randCode, 60); ?>

第三步：调用和显示验证码，在需要添加验证码的页面加入以下代码，代码如下：

<input name="yzm" type="text" class="input1" size="12" style="width:70px;"/> <SCRIPT LANGUAGE="JavaScript"><!--document.write('<img id="yz_Img" name="imageField" class="yz_Img" title="刷新验证码" onclick="this.src=this.src+Math.random();" src="yzimg.php?'+Math.random()+'">');//--></SCRIPT>

以上就是为大家分享的如何使用php生成动态验证码的相应代码，希望对大家的学习有所帮助。