使用代码生成图像缩略图与添加水印的方法

                           参数 原图片地址路径 新图片地址路径  新图片的宽 新图片的高  缩略图
 private void makeThumbnail(string sourcePath, string newPath, int width, int height)
        {
            System.Drawing.Image ig = System.Drawing.Image.FromFile(sourcePath);
            int towidth = width;
            int toheight = height;
            int x = 0;
            int y = 0;
            int ow = ig.Width;
            int oh = ig.Height;
            if ((double)ig.Width / (double)ig.Height > (double)towidth / (double)toheight)
            {
                oh = ig.Height;
                ow = ig.Height * towidth / toheight;
                y = 0;
                x = (ig.Width - ow) / 2;

            }
            else
            {
                ow = ig.Width;
                oh = ig.Width * height / towidth;
                x = 0;
                y = (ig.Height - oh) / 2;
            }
            System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);
            System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
            g.Clear(System.Drawing.Color.Transparent);
            g.DrawImage(ig, new System.Drawing.Rectangle(0, 0, towidth, toheight), new System.Drawing.Rectangle(x, y, ow, oh), System.Drawing.GraphicsUnit.Pixel);
            try
            {
                bitmap.Save(newPath, System.Drawing.Imaging.ImageFormat.Jpeg);
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                ig.Dispose();
                bitmap.Dispose();
                g.Dispose();
            }

        }









                         参数   原图片地址路径     添加在水印上的图片   添加在水印上的文字   生成新图片 水印图