这期内容当中小编将会给大家带来有关利用PHP怎么实现一个GIF图片验证码功能，文章内容丰富且以专业的角度为大家分析和叙述，阅读完这篇文章希望大家可以有所收获。
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 .= "!\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：
<?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" />
<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>上述就是小编为大家分享的利用PHP怎么实现一个GIF图片验证码功能了，如果刚好有类似的疑惑，不妨参照上述分析进行理解。如果想知道更多相关知识，欢迎关注亿速云行业资讯频道。
免责声明：本站发布的内容（图片、视频和文字）以原创、转载和分享为主，文章观点不代表本网站立场，如果涉及侵权请联系站长邮箱：is@yisu.com进行举报，并提供相关证据，一经查实，将立刻删除涉嫌侵权内容。
