產生縮圖

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        /// <summary>        /// 產生縮圖        /// </summary>        /// <param name="originalImagePath">源圖路徑（實體路徑）</param>        /// <param name="thumbnailPath">縮圖路徑（實體路徑）</param>        /// <param name="width">縮圖寬度</param>        /// <param name="height">縮圖高度</param>        /// <param name="mode">產生縮圖的方式</param>            public static void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode)        {            Image originalImage = Image.FromFile(originalImagePath);            int towidth = width;            int toheight = height;            int x = 0;            int y = 0;            int ow = originalImage.Width;            int oh = originalImage.Height;            switch (mode)            {                case "HW"://指定高寬縮放（可能變形）                                    break;                case "W"://指定寬，高按比例                                        toheight = originalImage.Height * width / originalImage.Width;                    break;                case "H"://指定高，寬按比例                    towidth = originalImage.Width * height / originalImage.Height;                    break;                case "Cut"://指定高寬裁減（不變形）                                    if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight)                    {                        oh = originalImage.Height;                        ow = originalImage.Height * towidth / toheight;                        y = 0;                        x = (originalImage.Width - ow) / 2;                    }                    else                    {                        ow = originalImage.Width;                        oh = originalImage.Width * height / towidth;                        x = 0;                        y = (originalImage.Height - oh) / 2;                    }                    break;                default:                    break;            }            //建立一個bmp圖片            Image bitmap = new System.Drawing.Bitmap(towidth, toheight);            //建立一個畫板            Graphics g = System.Drawing.Graphics.FromImage(bitmap);            //設定高品質插值法            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;            //設定高品質,低速度呈現平滑程度            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;            //清空畫布並以透明背景色填充            g.Clear(Color.Transparent);            //在指定位置並且按指定大小繪製原圖片的指定部分            g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight),                new Rectangle(x, y, ow, oh),                GraphicsUnit.Pixel);            try            {                //以jpg格式儲存縮圖                bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);            }            catch (System.Exception e)            {                throw e;            }            finally            {                originalImage.Dispose();                bitmap.Dispose();                g.Dispose();            }        }

 

產生縮圖