PHP生成图片缩略图类示例

classApp_image_helper {

  protected$imgFileName;

  protected$imgWidth;

  protected$imgHeight;

  protected$imgMime;

  protected$imgResource;

  static $imgMineList

    =array(

      'jpeg'=>'image/jpeg',

      'gif'=>'image/gif',

      'png'=>'image/png',

      'wbmp'=>'image/wbmp',

    );

  /**

   * 根据文件名，初始化图片，

   * 计算出给定图片的宽、高、图片类型，并获取图片的资源保存到内存，便于下次使用

   * App_image_helper constructor.

   *

   * @param $fileName

   */

  publicfunction__construct($fileName) {

    $this->imgFileName =$fileName;

    list($this->imgWidth,$this->imgHeight,$this->imgMime) =$this->getImageInfo($this->imgFileName);

    $this->imgResource =$this->getImageResource($this->imgFileName);

  }

  /**

   * 根据图片路径获取相关宽、高、MIME类型信息

   *

   * @param $fileName

   *

   * @return array|null

   */

  protectedfunctiongetImageInfo($fileName) {

    $result= null;

    if(is_file($fileName) ) {

      $tmpImageInfo=getimagesize($fileName);

      if($tmpImageInfo) {

        $result=array($tmpImageInfo[0],$tmpImageInfo[1],$tmpImageInfo['mime']);

      }

    }

    return$result;

  }

  /**

   * 将图片文件转为资源类类型

   *

   * @param $fileName

   *

   * @return null|resource

   */

  protectedfunctiongetImageResource($fileName) {

    $image= null;

    if(is_file($fileName) ) {

      switch($this->imgMime) {

        caseself::$imgMineList['jpeg']:

          $image= imagecreatefromjpeg($fileName);

          break;

        caseself::$imgMineList['gif']:

          $image= imagecreatefromgif($fileName);

          break;

        caseself::$imgMineList['png']:

          $image= imagecreatefrompng($fileName);

          break;

        caseself::$imgMineList['wbmp']:

          $image= imagecreatefromwbmp($fileName);

          break;

        default:

          break;

      }

    }

    return$image;

  }

  /**

   * 可根据固定宽，等比缩放图片；或根据百分比，等比缩放图片

   *

   * @param int $width

   * @param int $percent

   *

   * @return array|null

   */

  protectedfunctiongetSizeByScale($width= 360,$percent= 1) {

    $result= null;

    if($this->imgWidth &&$this->imgHeight ) {

      if($width) {

        $result=array($width,intval($width*$this->imgHeight /$this->imgWidth));

      }elseif($percent) {

        $result=array(intval($this->imgWidth *$percent),intval($this->imgHeight *$percent));

      }

    }

    return$result;

  }

  /**

   * 外调

   *

   * @param int $percentOrWidth int整数表示图片缩放为固定宽度，0.0~0.99999表示缩放百分比

   * @param null $fileName

   * @param int $quality

   * @param bool $reSample    重新采样图片，默认是

   *

   * @return bool

   */

  publicfunctioncreateImage($percentOrWidth= 1,$fileName= null,$quality= 75,$reSample= true) {

    $result= false;

    $fileName? header('Content-Type: '.$this->imgMime) : false;

    $size=$this->getSizeByScale(($percentOrWidth<= 1) ? null :$percentOrWidth,$percentOrWidth);

    if($size) {

      $thumb= imagecreatetruecolor($size[0],$size[1]);

      if($reSample) {

        imagecopyresampled($thumb,$this->imgResource, 0, 0, 0, 0,$size[0],$size[1],$this->imgWidth,$this->imgHeight);

      }else{

        imagecopyresized($thumb,$this->imgResource, 0, 0, 0, 0,$size[0],$size[1],$this->imgWidth,$this->imgHeight);

      }

      $result= imagejpeg($thumb,$fileName,$quality);

    }

    return$result;

  }

}