/**
   * Image constructor.
   * @param string $imagePath 图片路径
   * @param string $markPath 水印图片路径
   * @param int $new_width 缩略图宽度
   * @param int $new_height 缩略图高度
   * @param int $quality JPG图片格输出质量
   */
  public function __construct(string $imagePath,
                string $markPath = null,
                int $new_width = null,
                int $new_height = null,
                int $quality = 75)
  {
    $this->imgPath = $_SERVER['DOCUMENT_ROOT'] . $imagePath;
    $this->waterMarkPath = $markPath;
    $this->newWidth = $new_width "color: #800000">5.2. 生成缩略图函数_thumb()



   /**
   * 缩略图(按等比例,根据设置的宽度和高度进行裁剪)
   */
  private function _thumb()
  {

    //如果原图本身小于缩略图，按原图长高
    if ($this->newWidth > $this->width) $this->newWidth = $this->width;
    if ($this->newHeight > $this->height) $this->newHeight = $this->height;

    //背景图长高
    $gd_width = $this->newWidth;
    $gd_height = $this->newHeight;

    //如果缩略图宽高，其中有一边等于原图的宽高，就直接裁剪
    if ($gd_width == $this->width || $gd_height == $this->height) {
      $this->newWidth = $this->width;
      $this->newHeight = $this->height;
    } else {

      //计算缩放比率
      $per = 1;

      if (($this->newHeight / $this->height) > ($this->newWidth / $this->width)) {
        $per = $this->newHeight / $this->height;
      } else {
        $per = $this->newWidth / $this->width;
      }

      if ($per < 1) {
        $this->newWidth = $this->width * $per;
        $this->newHeight = $this->height * $per;
      }
    }

    $this->newImg = $this->_CreateImg($gd_width, $gd_height, $this->type);
    imagecopyresampled($this->newImg, $this->img, 0, 0, 0, 0, $this->newWidth, $this->newHeight, $this->width, $this->height);
  }




生成缩略图函数_thumb() ，是按照前面的分析来进行编码。 
5.3. 添加水印图片函数 _addWaterMark()    


   /**
   * 添加水印
   */
  private function _addWaterMark()
  {
    $ratio = 1 / 5; //水印缩放比率

    $Width = imagesx($this->newImg);
    $Height = imagesy($this->newImg);

    $n_width = $Width * $ratio;
    $n_height = $Width * $ratio;

    list($markWidth, $markHeight, $markType) = getimagesize($this->waterMarkPath);

    if ($n_width > $markWidth) $n_width = $markWidth;
    if ($n_height > $markHeight) $n_height = $markHeight;

    $Img = $this->_loadImg($this->waterMarkPath, $markType);
    $Img = $this->_thumb1($Img, $markWidth, $markHeight, $markType, $n_width, $n_height);
    $markWidth = imagesx($Img);
    $markHeight = imagesy($Img);
    imagecopyresampled($this->newImg, $Img, $Width - $markWidth - 10, $Height - $markHeight - 10, 0, 0, $markWidth, $markHeight, $markWidth, $markHeight);
    imagedestroy($Img);
  }




在添加水印图片中，用到一个_thumb1()函数来缩放水印图片：


  /**
   * 缩略图(按等比例)
   * @param resource $img 图像流
   * @param int $width
   * @param int $height
   * @param int $type
   * @param int $new_width
   * @param int $new_height
   * @return resource
   */
  private function _thumb1($img, $width, $height, $type, $new_width, $new_height)
  {

    if ($width < $height) {
      $new_width = ($new_height / $height) * $width;
    } else {
      $new_height = ($new_width / $width) * $height;
    }

    $newImg = $this->_CreateImg($new_width, $new_height, $type);
    imagecopyresampled($newImg, $img, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
    return $newImg;
  }





5.4. 完整代码：


<"color: #800000">new Image($_path, MARK, 400, 200, 100);

7.小结

这个Image 类能够生成缩略图，不出现黑边，添加水印图，能根据图片的大小缩放水印图。当然有个缺点，就是不能缩放GIF的动画，因为涉及到帧的处理，比较麻烦。
 以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。