php如何给图片添加水印的案例

<?php 
  /** 
   * 图片添加水印 
   * $target 源文件路径 
   * $wtrmrk_file 水印图片路径 
   * $newcopy 添加水印后的图片路径 
   * 
   */ 
  public function watermark_image($target, $wtrmrk_file, $newcopy) { 
    $watermark = imagecreatefrompng($wtrmrk_file); 
    imagealphablending($watermark, false); 
    imagesavealpha($watermark, true); 
    $img = imagecreatefromjpeg($target); 
    $img_w = imagesx($img); 
    $img_h = imagesy($img); 
    $wtrmrk_w = imagesx($watermark); 
    $wtrmrk_h = imagesy($watermark); 
    $dst_x = ($img_w ) – ($wtrmrk_w); // For centering the watermark on any image //phpfensi.com 
    $dst_y = ($img_h) – ($wtrmrk_h ); // For centering the watermark on any image 
    imagecopy($img, $watermark, $dst_x, $dst_y, 0, 0, $wtrmrk_w, $wtrmrk_h); 
     
    imagejpeg($img, $newcopy, 100); 
    imagedestroy($img); 
    imagedestroy($watermark); 
    //return $img; 
  } 
?>