PHP实现将上传图片自动缩放到指定分辨率，并保持清晰度封装类示例

class AutoImage{  private $image;  public function resize($src, $width, $height){    //$src 就是 $_FILES['upload_image_file']['tmp_name']    //$width和$height是指定的分辨率    //如果想按指定比例放缩，可以将$width和$height改为$src的指定比例    $this->image = $src;    $info = getimagesize($src);//获取图片的真实宽、高、类型    if($info[0] == $width && $info[1] == $height){      //如果分辨率一样，直接返回原图      return $src;    }    switch ($info['mime']){      case 'image/jpeg':        header('Content-Type:image/jpeg');        $image_wp = imagecreatetruecolor($width, $height);        $image_src = imagecreatefromjpeg($src);        imagecopyresampled($image_wp, $image_src, 0, 0, 0, 0, $width, $height, $info[0], $info[1]);        imagedestroy($image_src);        imagejpeg($image_wp,$this->image);        break;      case 'image/png':        header('Content-Type:image/png');        $image_wp = imagecreatetruecolor($width, $height);        $image_src = imagecreatefrompng($src);        imagecopyresampled($image_wp, $image_src, 0, 0, 0, 0, $width, $height, $info[0], $info[1]);        imagedestroy($image_src);        imagejpeg($image_wp,$this->image);        break;      case 'image/gif':        header('Content-Type:image/gif');        $image_wp = imagecreatetruecolor($width, $height);        $image_src = imagecreatefromgif($src);        imagecopyresampled($image_wp, $image_src, 0, 0, 0, 0, $width, $height, $info[0], $info[1]);        imagedestroy($image_src);        imagejpeg($image_wp,$this->image);        break;    }    return $this->image;  }}