<?php
//圖片處理工具類
class Image{
    //屬性
    private $thumb_width; //縮略圖的寬
    private $thumb_height;
    //錯誤屬性
    public $thumb_error;
    //構造方法
    public function __construct($width = 0,$height = 0){
      $this->thumb_width = ($width == 0) ? $GLOBALS['config']['admin_goods_thumb']['width'] : $width;
      $this->thumb_height = ($height == 0) ? $GLOBALS['config']['admin_goods_thumb']['height'] : $height;
    }
    /*
     * 制作縮略圖
     * @param1 string $src，原圖路徑，/uploads/20150122101010abcdef.gif
     * @param2 string $path，縮略圖保存路徑/uploads/thumb_20150122101010abcdef.gif
     * @return 縮略圖的名字
    */
    public function makeThumb($src,$path){
      //判斷原圖是否存在
      if(!file_exists($src)){
        $this->thumb_error = '原圖不存在！';
        return false;
      }
      //打開原圖資源
      //獲取能夠使用的后綴
      $ext = $this->getFunctionName($src); //gif
      //拼湊函數(shù)名
      $open = 'imagecreatefrom' . $ext;    //imagecreatefromgif
      $save = 'image' . $ext;          //imagegif
      //如果不清楚；echo $open,$save;exit;
      //可變函數(shù)打開原圖資源
      $src_img = $open($src); //利用可變函數(shù)打開圖片資源
      //imagecreatefromgif($src)
      //縮略圖資源
      $dst_img = imagecreatetruecolor($this->thumb_width,$this->thumb_height);
      //背景色填充白色
      $dst_bg_color = imagecolorallocate($dst_img,255,255,255);
      imagefill($dst_img,0,0,$dst_bg_color);
      //寬高比確定寬高
      $dst_size = $this->thumb_width / $this->thumb_height;
      //獲取原圖數(shù)據(jù)
      $file_info = getimagesize($src);
      $src_size = $file_info[0]/$file_info[1];
      //求出縮略圖寬和高
      if($src_size > $dst_size){
        //原圖寬高比大于縮略圖
        $width = $this->thumb_width;
        $height = round($width / $src_size);
      }else{
        $height = $this->thumb_height;
        $width = round($height * $src_size);
      }
      //求出縮略圖起始位置
      $dst_x = round($this->thumb_width - $width)/2;
      $dst_y = round($this->thumb_height - $height)/2;
      //制作縮略圖
      if(imagecopyresampled($dst_img,$src_img,$dst_x,$dst_y,0,0,$width,$height,$file_info[0],$file_info[1])){
        //采樣成功：保存，將文件保存到對應的路徑下
        $thumb_name = 'thumb_' . basename($src);
        $save($dst_img,$path . '/' . $thumb_name);
        //保存成功
        return $thumb_name;
      }else{
        //采樣失敗
        $this->thumb_error = '縮略圖采樣失敗！';
        return false;
      }
    }
    /*
     * 獲取文件要調用的函數(shù)名
     * @param1 string $file，文件名字
     * @return 通過文件后綴名得到的函數(shù)字符串
    */
    private function getFunctionName($file){
      //得到文件的后綴
      $file_info = pathinfo($file);
      $ext = $file_info['extension']; //后綴：gif,png,jpg,jpeg,pjpeg
      //imagecreatefromgif,imagecreatefromjpeg,imagecreatefrompng
      //定義一個數(shù)組保存函數(shù)名
      $func = array(
        'gif' => 'gif',
        'png' => 'png',
        'jpg' => 'jpeg',
        'jpeg' => 'jpeg',
        'pjpeg' => 'jpeg'
      );
      //返回值
      return $func[$ext];
    }
}