求生成缩略图的代码

// <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 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
            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);
            }
            catch(System.Exception e)
            {
                throw e;
            }
            finally
            {
                originalImage.Dispose();
                bitmap.Dispose();
                g.Dispose();
            }
        }生成高质量缩略图通用函数

同意一楼，不过有一点小的建议。
即然是高质量图形，就别用JPG格式了，用PNG比较好，无损压缩。
要是用JPG的话，前面就别用高质量，低速度了。

http://blog.csdn.net/wangjun8868/archive/2008/11/12/3283493.aspx

http://www.cnblogs.com/ghd258/archive/2006/02/26/337957.html

private static void MakeImg(string originalImagePath, string thumbnailPath, int width, int height, string mode)
        {
            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":
                    break;
                case "W":
                    toheight = originalImage.Height * width/originalImage.Width;
                    break;
                case "H":
                    towidth = originalImage.Width * height/originalImage.Height;
                    break;
                case "Cut":
                    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;
            }
            System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth,toheight);
            Graphics g = System.Drawing.Graphics.FromImage(bitmap);
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
            g.Clear(Color.Transparent);
            g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight),
                new Rectangle(x, y, ow,oh),
                GraphicsUnit.Pixel);
            try
            {
                bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
            }
            catch(System.Exception e)
            {
                throw e;
            }
            finally
            {
                originalImage.Dispose();
                bitmap.Dispose();
                g.Dispose();
            }
        }

http://blog.csdn.net/ojekleen/archive/2008/08/01/2754255.aspx

调试易

求生成缩略图的代码

解决方案 »