PHP生成图片缩略图类示例

class App_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 $fileName   */  public function __construct($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 $fileName   *   * @return array|null   */  protected function getImageInfo($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 $fileName   *   * @return null|resource   */  protected function getImageResource($fileName) {    $image = null;    if ( is_file($fileName) ) {      switch ($this->imgMime) {        case self::$imgMineList['jpeg']:          $image = imagecreatefromjpeg($fileName);          break;        case self::$imgMineList['gif']:          $image = imagecreatefromgif($fileName);          break;        case self::$imgMineList['png']:          $image = imagecreatefrompng($fileName);          break;        case self::$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 $percent   *   * @return array|null   */  protected function getSizeByScale($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 $reSample    重新采样图片，默认是   *   * @return bool   */  public function createImage($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;  }}