php实现图片上传时添加文字和图片水印技巧

本文实现的功能特别适用于一些商城和图片站中，分享了图片在上传时添加文字和图片水印的技巧，供大家参考，具体内容如下

1. water.class.php

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);
  } 
}

2. test1.php

watermark('12.jpg',5);
//$image->watermark('12.jpg',1);

3.效果图

以上就是本文的全部内容，希望对大家学习PHP程序设计有所帮助。