php 图片调整大小 封装类【转载】

 <?php
 class ImageResize
 {
     private $image;
     private $img_des;
     private $image_type;
     private $permissions;
     private $compression;

     /**
      * 构造函数
      * @param string $img_src     源图片
      * @param string $img_des     保存图片对象
      * @param int    $compression 压缩比率，范围0-100(0:压缩比最高，100：压缩比最低)
      * @param null   $permissions 改变文件模式
      *                            mode 参数由 4 个数字组成：
      *                            第一个数字永远是 0
      *                            第二个数字规定所有者的权限
      *                            第二个数字规定所有者所属的用户组的权限
      *                            第四个数字规定其他所有人的权限
      *                            1 - 执行权限，2 - 写权限，4 - 读权限
      */
     function __construct($img_src, $img_des = NULL, $compression = 75, $permissions = null)
     {
         $image_info = getimagesize($img_src);

         $this->img_des = $img_des;
         $this->image_type = $image_info[2];
         $this->compression = $compression;
         $this->permissions = $permissions;

         if ($this->image_type == IMAGETYPE_JPEG) {
             $this->image = ImageCreateFromJPEG($img_src);
         } elseif ($this->image_type == IMAGETYPE_GIF) {
             $this->image = ImageCreateFromGIF($img_src);
         } elseif ($this->image_type == IMAGETYPE_PNG) {
             $this->image = ImageCreateFromPNG($img_src);
         }
     }

     /**
      * 保存图片
      */
     function save()
     {
         if ($this->image_type == IMAGETYPE_JPEG) {
             imagejpeg($this->image, $this->img_des, $this->compression);
         } elseif ($this->image_type == IMAGETYPE_GIF) {
             imagegif($this->image, $this->img_des);
         } elseif ($this->image_type == IMAGETYPE_PNG) {
             imagepng($this->image, $this->img_des);
         }

         if ($this->permissions != null) {
             chmod($this->image, $this->compression);
         }
     }

     /**
      * 做为图片流直接输出
      */
     function output()
     {
         if ($this->image_type == IMAGETYPE_JPEG) {
             header('Content-Type: image/jpg');
             imagejpeg($this->image);
         } elseif ($this->image_type == IMAGETYPE_GIF) {
             header('Content-Type: image/gif');
             imagegif($this->image);
         } elseif ($this->image_type == IMAGETYPE_PNG) {
             header('Content-Type: image/png');
             imagepng($this->image);
         }
     }

     /**
      * 获取图片宽度
      * @return int 图片宽度
      */
     function getWidth()
     {
         return imagesx($this->image);
     }

     /*
      * 获取图片高度
      * @return int 图片高度
      */
     function getHeight()
     {
         return imagesy($this->image);
     }

     /**
      * 按照固定高度缩放图片
      * @param $height 需要改变大小的高度
      */
     function resizeToHeight($height)
     {
         $ratio = $height / $this->getHeight();
         $width = $this->getWidth() * $ratio;
         $this->resize($width, $height);
     }

     /**
      * 按照固定宽度缩放图片
      * @param $width 指定宽度
      */
     function resizeToWidth($width)
     {
         $ratio = $width / $this->getWidth();
         $height = $this->getheight() * $ratio;
         $this->resize($width, $height);
     }

     /**
      * 等比缩放图片
      * @param int $scale 缩放比例
      */
     function scale($scale)
     {
         $width = $this->getWidth() * $scale / 100;
         $height = $this->getheight() * $scale / 100;
         $this->resize($width, $height);
     }

     /**
      * 指定宽度和高度缩放图片
      * @param int $width  缩放宽度
      * @param int $height 缩放高度
      * @return 缩放后图片对象
      */
     function resize($width, $height)
     {
         $new_image = imagecreatetruecolor($width, $height);

         if ($this->image_type == IMAGETYPE_GIF || $this->image_type == IMAGETYPE_PNG) {
             $current_transparent = imagecolortransparent($this->image);
             if ($current_transparent != -1) {
                 $transparent_color = imagecolorsforindex($this->image, $current_transparent);
                 $current_transparent = imagecolorallocate($new_image, $transparent_color['red'], $transparent_color['green'], $transparent_color['blue']);
                 imagefill($new_image, 0, 0, $current_transparent);
                 imagecolortransparent($new_image, $current_transparent);
             } elseif ($this->image_type == IMAGETYPE_PNG) {
                 imagealphablending($new_image, false);
                 $color = imagecolorallocatealpha($new_image, 0, 0, 0, 127);
                 imagefill($new_image, 0, 0, $color);
                 imagesavealpha($new_image, true);
             }
         }

         imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight());
         $this->image = $new_image;
     }
 }

 ?>

使用方法：

 $image = new ImageResize($tmp_image_name, NULL, 100);
 $image->output();