code: func (b *Base) GetCropOption(name string) *image.Rectangle {
  	if cropOption := b.CropOptions[strings.Split(name, "@")[0]]; cropOption != nil {
  		return &image.Rectangle{
  			Min: image.Point{X: cropOption.X, Y: cropOption.Y},
  			Max: image.Point{X: cropOption.X + cropOption.Width, Y: cropOption.Y + cropOption.Height},
  		}
  	}
  	return nil
  }
docs: // GetCropOption get crop options