PHP给图片添加水印
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.codetc.com'; //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$waterStr = 'www.codetc.com'; //水印文字
public$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) {
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) {
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-$this->waterImg_info);
$this->y = rand(0,$this->srcImg_info-$this->waterImg_info);
break 1;
case 1: //上左
$this->x = 0;
$this->y = 0;
break 1;
case 2: //上中
$this->x = ($this->srcImg_info-$this->waterImg_info)/2;
$this->y = 0;
break 1;
case 3: //上右
$this->x = $this->srcImg_info-$this->waterImg_info;
$this->y = 0;
break 1;
case 4: //中左
$this->x = 0;
$this->y = ($this->srcImg_info-$this->waterImg_info)/2;
break 1;
case 5: //中中
$this->x = ($this->srcImg_info-$this->waterImg_info)/2;
$this->y = ($this->srcImg_info-$this->waterImg_info)/2;
break 1;
case 6: //中右
$this->x = $this->srcImg_info-$this->waterImg_info;
$this->y = ($this->srcImg_info-$this->waterImg_info)/2;
break 1;
case 7: //下左
$this->x = 0;
$this->y = $this->srcImg_info-$this->waterImg_info;
break 1;
case 8: //下中
$this->x = ($this->srcImg_info-$this->waterImg_info)/2;
$this->y = $this->srcImg_info-$this->waterImg_info;
break 1;
default: //下右
$this->x = $this->srcImg_info-$this->waterImg_info;
$this->y = $this->srcImg_info-$this->waterImg_info;
break 1;
}
}
private function waterimg() {
if ($this->srcImg_info <= $this->waterImg_info || $this->srcImg_info <= $this->waterImg_info){
die('水印比原图大！');
}
$this->waterpos();
$cut = imagecreatetruecolor($this->waterImg_info,$this->waterImg_info);
imagecopy($cut,$this->im,0,0,$this->x,$this->y,$this->waterImg_info,$this->waterImg_info);
$pct = $this->transparent;
imagecopy($cut,$this->water_im,0,0,0,0,$this->waterImg_info,$this->waterImg_info);
imagecopymerge($this->im,$cut,$this->x,$this->y,0,0,$this->waterImg_info,$this->waterImg_info,$pct);
}
private function waterstr() {
$rect = imagettfbbox($this->fontSize,0,$this->fontFile,$this->waterStr);
$w = abs($rect-$rect);
$h = abs($rect-$rect);
$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,$this->fontColor,$this->fontColor,$this->fontColor);
imagettftext($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) {
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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