c#生成缩略图

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region 生成缩略图

    ///<summary>     /// 生成缩略图     /// </summary>     /// <param name="originalImagePath">源图路径（物理路径）</param>     /// <param name="thumbnailPath">缩略图路径（物理路径）</param>     /// <param name="width">缩略图宽度</param>     /// <param name="height">缩略图高度</param>     /// <param name="mode">生成缩略图的方式</param>         public void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode,out string outthumbnailPath)    {        System.Drawing.Image originalImage = System.Drawing.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"://指定高宽缩放（可能变形）                                 break;            case "W"://指定宽，高按比例                                     toheight = originalImage.Height * width / originalImage.Width;                break;            case "H"://指定高，宽按比例                 towidth = originalImage.Width * height / originalImage.Height;                break;            case "Cut"://指定高宽裁减（不变形）                                 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;        }        //新建一个bmp图片         System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);        //新建一个画板         Graphics g = System.Drawing.Graphics.FromImage(bitmap);        //设置高质量插值法         g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;        //设置高质量,低速度呈现平滑程度         g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;        //清空画布并以透明背景色填充         g.Clear(Color.Transparent);        //在指定位置并且按指定大小绘制原图片的指定部分         g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight),         new Rectangle(x, y, ow, oh),         GraphicsUnit.Pixel);        try        {            //以jpg格式保存缩略图             bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);            outthumbnailPath = thumbnailPath;        }        catch (System.Exception e)        {            throw e;        }        finally        {            originalImage.Dispose();            bitmap.Dispose();            g.Dispose();        }    }    #endregion
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