使用GetThumbnailImage進行圖片縮放操作

/// <summary>
        /// 獲取等比例縮放圖片的方法
        /// </summary>
        /// <param name="imgPath">待縮放圖片路徑</param>
        /// <param name="savePath">縮放圖片保存路徑</param>
        /// <param name="format">縮放圖片保存的格式</param>
        /// <param name="scaling">要保持的寬度或高度</param>
        /// <param name="keepWidthOrHeight">如果為true則保持寬度為scaling，否則保持高度為scaling</param>
        /// <returns></returns>
        public bool GetThumbnail(string imgPath, string savePath, ImageFormat format, int scaling, bool keepWidthOrHeight)
        {
            try
            {
                using (Bitmap myBitmap = new Bitmap(imgPath))
                {
                    int width = 0;
                    int height = 0;
                    int tw = myBitmap.Width;//圖像的實際寬度
                    int th = myBitmap.Height;//圖像的實際高度
                    if (keepWidthOrHeight)//保持寬度
                    {
                        #region 自動保持寬度
                        if (scaling >= tw)
                        {
                            width = tw;
                            height = th;
                        }
                        else
                        {
                            double ti = Convert.ToDouble(tw) / Convert.ToDouble(scaling);
                            if (ti == 0d)
                            {
                                width = tw;
                                height = th;
                            }
                            else
                            {
                                width = scaling;
                                height = Convert.ToInt32(Convert.ToDouble(th) / ti);
                            }
                        }
                        #endregion
                    }
           &nb