How to use the @antv/g.Rect function in @antv/g

this.isFlipped = true;
    const maxItemWidth = this.get('maxItemWidth');
    const maxItemHeight = this.get('maxItemHeight');
    const maxWidth = this.get('maxWidth');
    const maxHeight = this.get('maxHeight');
    const itemsGroup = this.get('itemsGroup');
    const itemsBBox = itemsGroup.getBBox();
    const layout = this.get('layout');
    const paginationCfg = this._getPaginationCfg();
    // 根据layout创建clip
    let pageNumber = 0;
    let mode = 'up-down'; // 上下翻页
    let x = itemsBBox.tl.x;
    let y = itemsBBox.tl.y; // 翻页器位置
    let size = 0; // 翻页器尺寸
    const clip = new Rect({
      attrs: {
        x,
        y,
        width: maxWidth - paginationCfg.size,
        height: maxHeight,
      },
    });
    if (layout === 'horizontal') {
      const width = Math.max(maxWidth, itemsBBox.width);
      clip.attr('width', width);
      clip.attr('height', maxItemHeight);
      this.set('maxWidth', width);
      this.set('maxHeight', maxItemHeight);
      pageNumber = Math.ceil(itemsBBox.height / (maxItemHeight + this.get('itemMarginBottom')));
      x = x + width - paginationCfg.size; // temp:padding
      y = Math.ceil(y + maxItemHeight / 2);

}
    // 支持circle、rect、ellipse、Polygon及自定义path clip
    const { type, x, y } = clip;
    let clipShape = null;
    if (type === 'circle') {
      const { r } = clip;
      clipShape = new G.Circle({
        attrs: {
          r,
          x,
          y
        }
      });
    } else if (type === 'rect') {
      const { width, height } = clip;
      clipShape = new G.Rect({
        attrs: {
          x,
          y,
          width,
          height
        }
      });
    } else if (type === 'ellipse') {
      const { rx, ry } = clip;
      clipShape = new G.Ellipse({
        attrs: {
          x,
          y,
          rx,
          ry
        }