//通过构造方法队成员属性进行初始化
function __construct($path='./',$isRandName=true,$type='png'){
$this->path = $path;
$this->isRandName = $isRandName;
$this->type = $type;
}
//对外公开的水印方法

/**

• @param char $image 原图
• @param char $water 水印图片
• @param char $postion 位置
• @param int $tmp 透明度
• @param char $prefix 前缀
  */
  function water($image,$water,$postion,$tmp=100,$prefix='water_'){
  //判断这两个图片是否存在
  if(!file_exists($image)||!file_exists($water)){
  die('图片资源不存在');
  }
  //得到原图和水印图片的宽高
  $imageInfo = self::getImageInfo($image);
  $waterInfo = self::getImageInfo($water);
  //判断水印图片是否能贴上来
  if (!$this->checkImage($imageInfo,$waterInfo)){
  die('水印图片太大');
  }
  //打开图片
  $imageRes = self::openAnyImage($image);
  $waterRes = self::openAnyImage($water);
  //根据水印图片的位置计算水印图片的坐标
  $pos = $this->getPosition($postion,$imageInfo,$waterInfo);
  //将水印图片贴过来
  imagecopymerge($imageRes,$waterRes,$pos['x'],$pos['y'],$waterInfo["width"],$waterInfo["height"],$tmp);
  //得到要保存图片的文件名
  $newName = $this->createNewName($image,$prefix);
  //得到保存图片的路径,也就是文件的全路径
  $newPath = rtrim($this->path,'/').'/'.$newName;
  //保存图片
  $this->saveImage($imageRes,$newPath);
  //销毁资源
  imagedestroy($imageRes);
  imagedestroy($waterRes);

//返回路径
return $newPath;

}
//保存图像资源
protected function saveImage($imageRes,$newPath){
$func = 'image'.$this->type;
//通过变量函数进行保存
$func($imageRes,$newPath);
}
//得到文件名函数
protected function createNewName($imagePath,$prefix){
if ($this->isRandName){
$name = $prefix.uniqid().'.'.$this->type;
}else {
$name = $prefix.pathinfo($imagePath)['filename'].'.'.$this->type;
}
return $name;
}
//根据位置计算水印图片的坐标
protected function getPosition($postion,$waterInfo){
switch ($postion){
case 1:
$x = 0;
$y = 0;
break;
case 2:
$x = ($imageInfo['width']-$waterInfo["width"])/2;
$y = 0;
break;
case 3:
$x = $imageInfo["width"]- $waterInfo["width"];
$y = 0;
break;
case 4:
$x = 0;
$y = ($imageInfo["height"]-$waterInfo["height"])/2;
break;
case 5:
$x = ($imageInfo['width']-$waterInfo["width"])/2;
$y = ($imageInfo["height"]-$waterInfo["height"])/2;
break;
case 6:
$x = $imageInfo["width"]- $waterInfo["width"];
$y = ($imageInfo["height"]-$waterInfo["height"])/2;
break;
case 7:
$x = 0;
$y = $imageInfo['height'] - $waterInfo["height"];
break;
case 8:
$x = ($imageInfo['width']-$waterInfo["width"])/2;
$y = $imageInfo['height'] - $waterInfo["height"];
break;
case 9:
$x = $imageInfo["width"]- $waterInfo["width"];
$y = $imageInfo['height'] - $waterInfo["height"];
break;
case 0:
$x = mt_rand(0,$imageInfo["width"]- $waterInfo["width"]);
$y = mt_rand(0,$imageInfo['height'] - $waterInfo["height"]);
break;
}
return ['x'=>$x,'y'=>$y];
}
protected function checkImage($imageInfo,$waterInfo){
if (($waterInfo['width'] > $imageInfo['width'])||($waterInfo['height'] > $imageInfo['height'])){
return false;
}
return true;
}
//静态方法。根据图片的路径得到图片的信息，宽度，高度、mime类型
static function getImageInfo($imagePath){
$info = getimagesize($imagePath);
$data['width']=$info[0];
$data['height']=$info[1];
$data['mime'] = $info['mime'];
return $data;
}
static function openAnyImage($imagePath){
//得到图像的mime类型
$mime = self::getImageInfo($imagePath)['mime'];
//根据不同的mime类型打开不同的图像
switch ($mime){
case 'image/png':
$image = imagecreatefrompng($imagePath);
break;
case 'image/gif':
$image = imagecreatefromgif($imagePath);
break;
case 'image/jpeg':
$image = imagecreatefromjpeg($imagePath);
break;
case 'image/wbmp':
$image = imagecreatefromwbmp($imagePath);
break;
}
return $image;
}

}