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"; /* 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 .= "!37713netscape2.031" . gifencoder::gifword ( $this->lop ) . " ";
}
}
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)));
$locals_ext = "!xf9x04" . chr(($this->dis << 2) + 0) . chr(($d >> 0) & 0xff) . chr(($d >> 8) & 0xff) . "x0x0";
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 )
{
$locals_ext = "!xf9x04" . chr(($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：
<?php
if(!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session
imagecode($randcode, 60);
/*方法二*/
/*$authstr = mt_rand(1000, 9999); // 生成随机字符串
$_session['yzm'] = $authstr; // 记录session
imagecode($authstr, 60); // 显示gif动画*/
?>
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。
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