PHP实现GIF图片验证码

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 .= "!\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" 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。