<?PHP
//影象處理類
class Image {
    private $file;    //圖片地址
    private $width;   //圖片長度
    private $height;   //圖片長度
    private $type;    //圖片型別
    private $img;    //原圖的資源控制代碼
    private $new;    //新圖的資源控制代碼
 
    //構造方法，初始化
    public function __construct($_file) {
        $this->file = $_file;
        list($this->width, $this->height, $this->type) = getimagesize($this->file);
        $this->img = $this->getFromImg($this->file, $this->type);
    }
    //縮圖(固定長高容器，影象等比例，擴容填充，裁剪)[固定了大小，不失真，不變形]
    public function thumb($new_width = 0,$new_height = 0) {
  
        if (empty($new_width) && empty($new_height)) {
			$new_width = $this->width;
			$new_height = $this->height;
        }
  
		if (!is_numeric($new_width) || !is_numeric($new_height)) {
			$new_width = $this->width;
			$new_height = $this->height;
		}
  
		//建立一個容器
		$_n_w = $new_width;
		$_n_h = $new_height;
	  
		//建立裁剪點
		$_cut_width = 0;
		$_cut_height = 0;
	  
		if ($this->width < $this->height) {
			$new_width = ($new_height / $this->height) * $this->width;
		} else {
			$new_height = ($new_width / $this->width) * $this->height;
		}
		if ($new_width < $_n_w) { //如果新高度小於新容器高度
			$r = $_n_w / $new_width; //按長度求出等比例因子
			$new_width *= $r; //擴充套件填充後的長度
			$new_height *= $r; //擴充套件填充後的高度
			$_cut_height = ($new_height - $_n_h) / 2; //求出裁剪點的高度
		}
	  
		if ($new_height < $_n_h) { //如果新高度小於容器高度
			$r = $_n_h / $new_height; //按高度求出等比例因子
			$new_width *= $r; //擴充套件填充後的長度
			$new_height *= $r; //擴充套件填充後的高度
			$_cut_width = ($new_width - $_n_w) / 2; //求出裁剪點的長度
		}
 
        $this->new = imagecreatetruecolor($_n_w,$_n_h);
        imagecopyresampled($this->new,$this->img,0,0,$_cut_width,$_cut_height,$new_width,$new_height,$this->width,$this->height);
    }
 
    //載入圖片，各種型別，返回圖片的資源控制代碼
    private function getFromImg($_file, $_type) {
        switch ($_type) {
			case 1 :
				$img = imagecreatefromgif($_file);
				break;
			case 2 :
				$img = imagecreatefromjpeg($_file);
				break;
			case 3 : 
				$img = imagecreatefrompng($_file);
				break;
			default:
				$img = '';
        }
        return $img;
    }
 
    //影象輸出
    public function out() {
        imagepng($this->new,$this->file);//第二個引數為新生成的圖片名
        imagedestroy($this->img);
        imagedestroy($this->new);
    }
}
//使用demo
$_path = '1.jpg';//$_path為圖片檔案的路徑
$_img = new Image($_path);
$_img->thumb(100, 100);
$_img->out();
 
?>