C# 生成缩略图

个人觉得比较好用的缩略图方法，用在每次从ftp服务端下载图片，之后引用该方法进行压缩图片；

/// <summary>
        /// 生成缩略图
        /// </summary>
        /// <param name="localimagepath">图片地址</param>
        /// <param name="thumbnailimagepath">缩略图地址</param>
        /// <param name="width">图片宽度</param>
        /// <param name="height">图片高度</param>
        /// <param name="p"></param>
        public static void getthumbnail(string localimagepath, string thumbnailimagepath, int width, int height)
        {
            system.drawing.image serverimage = system.drawing.image.fromfile(localimagepath);
            //画板大小
            int towidth = width;
            int toheight = height;
            //缩略图矩形框的像素点
            int x = 0;
            int y = 0;
            int ow = serverimage.width;
            int oh = serverimage.height;
 
            if (ow > oh)
            {
                toheight = serverimage.height * width / serverimage.width;
            }
            else
            {
                towidth = serverimage.width * height / serverimage.height;
            }
            //新建一个bmp图片
            system.drawing.image bm = new system.drawing.bitmap(width, height);
            //新建一个画板
            system.drawing.graphics g = system.drawing.graphics.fromimage(bm);
            //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(system.drawing.color.white);
            //在指定位置并且按指定大小绘制原图片的指定部分
            g.drawimage(serverimage, new system.drawing.rectangle((width - towidth) / 2, (height - toheight) / 2, towidth, toheight),
                0, 0, ow, oh,
                system.drawing.graphicsunit.pixel);
            try
            {
                //以jpg格式保存缩略图
                bm.save(thumbnailimagepath, system.drawing.imaging.imageformat.jpeg);
            }
            catch (system.exception e)
            {
                throw e;
            }
            finally
            {
                serverimage.dispose();
                bm.dispose();
                g.dispose();
            }
        }

　　转载自:http://www.wxzzz.com/1413.html