<?php
header('Content-Type:text/html;charset=utf-8');
/* 
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
//给图片添加水印
Class Water{
  //开启水印
  private $watermark_on = '1';
   
  public $water_img;
   
  //水印位置
  public $pos = 1;  
   
  //压缩比
  public $pct = 80;
   
  //透明度
  public $quality = 80;
   
  public $text = '乐趣网zlblog.sinaapp.com';
   
  public $size = 12;
   
  public $color = '#000000';
   
  public $font = 'font.ttf';
   
  public function watermark( $img,$pos='',$out_img='',$water_img='',$text='' ){
    if(!$this->check($img) || !$this->watermark_on) return false;
     
    $water_img = $water_img ? $water_img : $this->water_img;
    //水印的开启状态
    $waterimg_on = $this->check($water_img) ? 1 : 0;
    //判断是否在原图上操作
    $out_img = $out_img ? $out_img : $img;
    //判断水印的位置
    $pos = $pos ? $pos : $this->pos;
    //水印文字
    $text = $text ? $text : $this->text;
     
     
    $img_info = getimagesize($img);
    $img_w = $img_info[0];
    $img_h = $img_info[1];
    //判断水印图片的类型
     
     
    if( $waterimg_on ){
      $w_info = getimagesize($water_img);
      $w_w = $w_info[0];
      $w_h = $w_info[1];
      if ( $img_w < $w_w || $img_h < $w_h ) return false;
      switch ( $w_info[2] ){
        case 1:
          $w_img = imagecreatefromgif($water_img);
          break;
        case 2:
          $w_img = imagecreatefromjpeg($water_img);
          break;
        case 3:
          $w_img = imagecreatefrompng($water_img);
          break;
      }
    }else{
      if( empty($text) || strlen($this->color)!=7 ) return FALSE;
      $text_info = imagettfbbox($this->size, 0, $this->font, $text);
      $w_w = $text_info[2] - $text_info[6];
      $w_h = $text_info[3] - $text_info[7];
    }
     
    //建立原图资源
     
    switch ( $img_info[2] ){
      case 1:
        $res_img = imagecreatefromgif($img);
        break;
      case 2:
        $res_img = imagecreatefromjpeg($img);
        break;
      case 3:
        $res_img = imagecreatefrompng($img);
        break;
    }
    //确定水印的位置
    switch ( $pos ){
      case 1:
        $x = $y =25;
        break;
      case 2:
        $x = ($img_w - $w_w)/2; 
        $y = 25;
        break;
      case 3:
        $x = $img_w - $w_w;
        $y = 25;
        break;
      case 4:
        $x = 25;
        $y = ($img_h - $w_h)/2;
        break;
      case 5:
        $x = ($img_w - $w_w)/2; 
        $y = ($img_h - $w_h)/2;
        break;
      case 6:
        $x = $img_w - $w_w;
        $y = ($img_h - $w_h)/2;
        break;
      case 7:
        $x = 25;
        $y = $img_h - $w_h;
        break;
      case 8:
        $x = ($img_w - $w_w)/2;
        $y = $img_h - $w_h;
        break;
      case 9:
        $x = $img_w - $w_w;
        $y = $img_h - $w_h;
        break;
      default :
        $x = mt_rand(25, $img_w - $w_w);
        $y = mt_rand(25, $img_h - $w_h);
    }
     
    //写入图片资源
    if( $waterimg_on ){
      imagecopymerge($res_img, $w_img, $x, $y, 0, 0, $w_w, $w_h, $this->pct); 
  }else{
    $r = hexdec(substr($this->color, 1,2));
    $g = hexdec(substr($this->color, 3,2));
    $b = hexdec(substr($this->color, 5,2));
    $color = imagecolorallocate($res_img, $r, $g, $b);
    imagettftext($res_img, $this->size, 0, $x, $y, $color, $this->font, $text);  
  }
   
  //生成图片类型
  switch ( $img_info[2] ){
    case 1:
      imagecreatefromgif($res_img,$out_img);
      break;
    case 2:
      //imagecreatefromjpeg($res_img,$out_img);
      imagejpeg($res_img,$out_img);
      break;
    case 3:
      imagejpeg($res_img,$out_img);
      break;
  }
  if(isset($res_img)) imagedestroy ($res_img);
  if(isset($w_img))  imagedestroy($w_img);
  return TRUE;
}  
  //验证图片是否存在
    private function check($img){
      $type = array('.jpg','.jpeg','.png','.gif');
      $img_type = strtolower(strrchr($img, '.'));
      return extension_loaded('gd') && file_exists($img) && in_array($img_type, $type);
    } 
}

<?php
 
/* 
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
//header('Content-Type:text/html;charset=utf-8');
include 'water.class.php';
$image = new Water();
$image->watermark('12.jpg',5);
//$image->watermark('12.jpg',1);