完美png图片添加水印类

被添加水印图片和水印图片都可以是png，保证透明无色背景，可调节透明度

<?php
class Imgshuiyin{
/* 缩略图相关常量定义 */
const THUMB_SCALING = 1; //常量，标识缩略图等比例缩放类型
const THUMB_FILLED = 2; //常量，标识缩略图缩放后填充类型
const THUMB_CENTER = 3; //常量，标识缩略图居中裁剪类型
const THUMB_NORTHWEST = 4; //常量，标识缩略图左上角裁剪类型
const THUMB_SOUTHEAST = 5; //常量，标识缩略图右下角裁剪类型
const THUMB_FIXED = 6; //常量，标识缩略图固定尺寸缩放类型
/* 水印相关常量定义 */
const WATER_NORTHWEST = 1; //常量，标识左上角水印
const WATER_NORTH = 2; //常量，标识上居中水印
const WATER_NORTHEAST = 3; //常量，标识右上角水印
const WATER_WEST = 4; //常量，标识左居中水印
const WATER_CENTER = 5; //常量，标识居中水印
const WATER_EAST = 6; //常量，标识右居中水印
const WATER_SOUTHWEST = 7; //常量，标识左下角水印
const WATER_SOUTH = 8; //常量，标识下居中水印
const WATER_SOUTHEAST = 9; //常量，标识右下角水印
/* 翻转相关常量定义 */
const FLIP_X = 1; //X轴翻转
const FLIP_Y = 2; //Y轴翻转
/**
* 图像资源对象
*
* @var resource
*/
protected $im;
protected function __construct(\SplFileInfo $file)
{
//获取图像信息
$info = @getimagesize($file->getPathname());

//检测图像合法性
if (false === $info || (IMAGETYPE_GIF === $info[2] && empty($info['bits']))) {
//throw new ImageException('Illegal image file');
}

//设置图像信息
$this->info = [
'width' => $info[0],
'height' => $info[1],
'type' => image_type_to_extension($info[2], false),
'mime' => $info['mime'],
];

//打开图像
if ('gif' == $this->info['type']) {
//$this->gif = new Gif($file->getPathname());
//$this->im = @imagecreatefromstring($this->gif->image());
} else {
$fun = "imagecreatefrom{$this->info['type']}";
$this->im = @$fun($file->getPathname());
}

if (empty($this->im)) {
//throw new ImageException('Failed to create image resources!');
}

}
/**
* 打开一个图片文件
* @param \SplFileInfo|string $file
* @return Image
*/
public static function open($file)
{
if (is_string($file)) {
$file = new \SplFileInfo($file);
}
if (!$file->isFile()) {
//throw new ImageException('image file not exist');
}
return new self($file);
}
/**
* 添加水印
*
* @param string $source 水印图片路径
* @param int $locate 水印位置
* @param int $alpha 透明度
* @return $this
*/
public function water($source, $locate = 5, $alpha = 100)
{
if (!is_file($source)) {
// throw new ImageException('水印图像不存在');
}
//获取水印图像信息
$info = getimagesize($source);
if (false === $info || (IMAGETYPE_GIF === $info[2] && empty($info['bits']))) {
//throw new ImageException('非法水印文件');
}
//创建水印图像资源
$fun = 'imagecreatefrom' . image_type_to_extension($info[2], false);
$water = $fun($source);
//设定水印图像的混色模式
imagealphablending($water, true);
/* 设定水印位置 */
switch ($locate) {
/* 右下角水印 */
case self::WATER_SOUTHEAST:
$x = $this->info['width'] - $info[0];
$y = $this->info['height'] - $info[1];
break;
/* 左下角水印 */
case self::WATER_SOUTHWEST:
$x = 0;
$y = $this->info['height'] - $info[1];
break;
/* 左上角水印 */
case self::WATER_NORTHWEST:
$x = $y = 0;
break;
/* 右上角水印 */
case self::WATER_NORTHEAST:
$x = $this->info['width'] - $info[0];
$y = 0;
break;
/* 居中水印 */
case self::WATER_CENTER:
$x = ($this->info['width'] - $info[0]) / 2;
$y = ($this->info['height'] - $info[1]) / 2;
break;
/* 下居中水印 */
case self::WATER_SOUTH:
$x = ($this->info['width'] - $info[0]) / 2;
$y = $this->info['height'] - $info[1];
break;
/* 右居中水印 */
case self::WATER_EAST:
$x = $this->info['width'] - $info[0];
$y = ($this->info['height'] - $info[1]) / 2;
break;
/* 上居中水印 */
case self::WATER_NORTH:
$x = ($this->info['width'] - $info[0]) / 2;
$y = 0;
break;
/* 左居中水印 */
case self::WATER_WEST:
$x = 0;
$y = ($this->info['height'] - $info[1]) / 2;
break;
default:
/* 自定义水印坐标 */
if (is_array($locate)) {
list($x, $y) = $locate;
} else {
// throw new ImageException('不支持的水印位置类型');
}
}
do {
//添加水印
$src = imagecreatetruecolor($info[0], $info[1]);
// 调整默认颜色
$color = imagecolorallocate($src, 0, 0, 0);
//设置透明
imagecolortransparent($src,$color);
imagefill($src, 0, 0, $color);
imagecopy($src, $this->im, 0, 0, $x, $y, $info[0], $info[1]);
imagecopy($src, $water, 0, 0, 0, 0, $info[0], $info[1]);
imagecopymerge($this->im, $src, $x, $y, 0, 0, $info[0], $info[1], $alpha);
//销毁零时图片资源
imagedestroy($src);
} while (!empty($this->gif) && $this->gifNext());
//销毁水印资源
imagedestroy($water);
return $this;
} /**
* 保存图像
* @param string $pathname 图像保存路径名称
* @param null|string $type 图像类型
* @param int $quality 图像质量
* @param bool $interlace 是否对JPEG类型图像设置隔行扫描
* @return $this
*/
public function save($pathname, $type = null, $quality = 80, $interlace = true)
{
//自动获取图像类型
if (is_null($type)) {
$type = $this->info['type'];
} else {
$type = strtolower($type);
}
//保存图像
if ('jpeg' == $type || 'jpg' == $type) {
//JPEG图像设置隔行扫描
imageinterlace($this->im, $interlace);
imagejpeg($this->im, $pathname, $quality);
} elseif ('gif' == $type && !empty($this->gif)) {
$this->gif->save($pathname);
} elseif ('png' == $type) {
//设定保存完整的 alpha 通道信息
imagesavealpha($this->im, true);
//ImagePNG生成图像的质量范围从0到9的
imagepng($this->im, $pathname, min((int) ($quality / 10), 9));
} else {
$fun = 'image' . $type;
$fun($this->im, $pathname);
}

return $this;
}
}