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)：

/**

* 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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