PHP添加文字水印或图片水印的水印类完整源代码与使用示例

php实现的给图片添加水印功能，可添加文字水印或图片水印，使用文字水印时需要提供字体文件，使用图片水印时需要提供水印图片，水印图片不能比要添加水印的图片大，请使用背景透明的水印图片。

该水印类支持自定义水印位置、自定义水印大小和水印的透明度，字体水印可自定义颜色等，功能已相应完善。

完整源代码如下(注解中已给出使用示例)：

<?php
/**
 * 图片加水印类，支持文字水印、透明度设置、自定义水印位置等。
 * 使用示例：
 *   $obj = new watermask($imgfilename);  //实例化对象
 *   $obj->$watertype = 1;   //类型：0为文字水印、1为图片水印
 *   $obj->$transparent = 45;   //水印透明度
 *   $obj->$waterstr = 'www.jb51.net';  //水印文字
 *   $obj->$fontsize = 18;   //文字字体大小
 *   $obj->$fontcolor = array(255,255,255);  //水印文字颜色（rgb）
 *   $obj->$fontfile = 'ahgbold.ttf';  //字体文件
 * ……
 *   $obj->output();    //输出水印图片文件覆盖到输入的图片文件
 */
class watermask{
  public $watertype     = 0;   //水印类型：0为文字水印、1为图片水印
  public $pos        = 0;   //水印位置
  public $transparent    = 45;   //水印透明度
  public $waterstr      = 'www.jb51.net';  //水印文字
  public $fontsize      = 18;   //文字字体大小
  public $fontcolor     = array(255,255,255);  //水印文字颜色（rgb）
  public $fontfile      = 'ahgbold.ttf';  //字体文件
  public $waterimg      = 'logo.png';  //水印图片
  private $srcimg       = '';   //需要添加水印的图片
  private $im         = '';   //图片句柄
  private $water_im      = '';   //水印图片句柄
  private $srcimg_info    = '';   //图片信息
  private $waterimg_info   = '';   //水印图片信息
  private $str_w       = '';   //水印文字宽度
  private $str_h       = '';   //水印文字高度
  private $x         = '';   //水印x坐标
  private $y         = '';   //水印y坐标
  function __construct($img) {    //析构函数
    $this->srcimg = file_exists($img) ? $img : die('"'.$img.'" 源文件不存在！');
  }
  private function imginfo() { //获取需要添加水印的图片的信息，并载入图片。
    $this->srcimg_info = getimagesize($this->srcimg);
    switch ($this->srcimg_info[2]) {
      case 3:
        $this->im = imagecreatefrompng($this->srcimg);
        break 1;
      case 2:
        $this->im = imagecreatefromjpeg($this->srcimg);
        break 1;
      case 1:
        $this->im = imagecreatefromgif($this->srcimg);
        break 1;
      default:
        die('原图片（'.$this->srcimg.'）格式不对，只支持png、jpeg、gif。');
    }
  }
  private function waterimginfo() { //获取水印图片的信息，并载入图片。
    $this->waterimg_info = getimagesize($this->waterimg);
    switch ($this->waterimg_info[2]) {
      case 3:
        $this->water_im = imagecreatefrompng($this->waterimg);
        break 1;
      case 2:
        $this->water_im = imagecreatefromjpeg($this->waterimg);
        break 1;
      case 1:
        $this->water_im = imagecreatefromgif($this->waterimg);
        break 1;
      default:
        die('水印图片（'.$this->srcimg.'）格式不对，只支持png、jpeg、gif。');
    }
  }
  private function waterpos() { //水印位置算法
    switch ($this->pos) {
      case 0:   //随机位置
        $this->x = rand(0,$this->srcimg_info[0]-$this->waterimg_info[0]);
        $this->y = rand(0,$this->srcimg_info[1]-$this->waterimg_info[1]);
        break 1;
      case 1:   //上左
        $this->x = 0;
        $this->y = 0;
        break 1;
      case 2:   //上中
        $this->x = ($this->srcimg_info[0]-$this->waterimg_info[0])/2;
        $this->y = 0;
        break 1;
      case 3:   //上右
        $this->x = $this->srcimg_info[0]-$this->waterimg_info[0];
        $this->y = 0;
        break 1;
      case 4:   //中左
        $this->x = 0;
        $this->y = ($this->srcimg_info[1]-$this->waterimg_info[1])/2;
        break 1;
      case 5:   //中中
        $this->x = ($this->srcimg_info[0]-$this->waterimg_info[0])/2;
        $this->y = ($this->srcimg_info[1]-$this->waterimg_info[1])/2;
        break 1;
      case 6:   //中右
        $this->x = $this->srcimg_info[0]-$this->waterimg_info[0];
        $this->y = ($this->srcimg_info[1]-$this->waterimg_info[1])/2;
        break 1;
      case 7:   //下左
        $this->x = 0;
        $this->y = $this->srcimg_info[1]-$this->waterimg_info[1];
        break 1;
      case 8:   //下中
        $this->x = ($this->srcimg_info[0]-$this->waterimg_info[0])/2;
        $this->y = $this->srcimg_info[1]-$this->waterimg_info[1];
        break 1;
      default:  //下右
        $this->x = $this->srcimg_info[0]-$this->waterimg_info[0];
        $this->y = $this->srcimg_info[1]-$this->waterimg_info[1];
        break 1;
    }
  }
  private function waterimg() {
    if ($this->srcimg_info[0] <= $this->waterimg_info[0] || $this->srcimg_info[1] <= $this->waterimg_info[1]){
      die('水印比原图大！');
    }
    $this->waterpos();
    $cut = imagecreatetruecolor($this->waterimg_info[0],$this->waterimg_info[1]);
    imagecopy($cut,$this->im,0,0,$this->x,$this->y,$this->waterimg_info[0],$this->waterimg_info[1]);
    $pct = $this->transparent;
    imagecopy($cut,$this->water_im,0,0,0,0,$this->waterimg_info[0],$this->waterimg_info[1]);
    imagecopymerge($this->im,$cut,$this->x,$this->y,0,0,$this->waterimg_info[0],$this->waterimg_info[1],$pct);
  }
  private function waterstr() {
    $rect = imagettfbbox($this->fontsize,0,$this->fontfile,$this->waterstr);
    $w = abs($rect[2]-$rect[6]);
    $h = abs($rect[3]-$rect[7]);
    $fontheight = $this->fontsize;
    $this->water_im = imagecreatetruecolor($w, $h);
    imagealphablending($this->water_im,false);
    imagesavealpha($this->water_im,true);
    $white_alpha = imagecolorallocatealpha($this->water_im,255,255,255,127);
    imagefill($this->water_im,0,0,$white_alpha);
    $color = imagecolorallocate($this->water_im,$this->fontcolor[0],$this->fontcolor[1],$this->fontcolor[2]);
    imagettftext($this->water_im,$this->fontsize,0,0,$this->fontsize,$color,$this->fontfile,$this->waterstr);
    $this->waterimg_info = array(0=>$w,1=>$h);
    $this->waterimg();
  }
  function output() {
    $this->imginfo();
    if ($this->watertype == 0) {
      $this->waterstr();
    }else {
      $this->waterimginfo();
      $this->waterimg();
    }
    switch ($this->srcimg_info[2]) {
      case 3:
        imagepng($this->im,$this->srcimg);
        break 1;
      case 2:
        imagejpeg($this->im,$this->srcimg);
        break 1;
      case 1:
        imagegif($this->im,$this->srcimg);
        break 1;
      default:
        die('添加水印失败！');
        break;
    }
    imagedestroy($this->im);
    imagedestroy($this->water_im);
  }
}
?>

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