将图片压缩成大小格式小的图片

将对图片的操作单独写一个内，代码如下：

public class DoPic
    {

        /// <summary>
        /// 将图片转成二进制流
        /// </summary>
        /// <param name="path"></param>
        /// <returns></returns>
        public static byte[] SaveImage(String path)
        {
            FileStream fs = new FileStream(path, FileMode.Open, FileAccess.Read); //将图片以文件流的形式进行保存
            BinaryReader br = new BinaryReader(fs);
            byte[] imgBytesIn = br.ReadBytes((int)fs.Length); //将流读入到字节数组中
            return imgBytesIn;
        }


        /// <summary>
        /// 现实二进制流代表的图片
        /// </summary>
        /// <param name="imgBytesIn"></param>
        public static void ShowImgByByte(byte[] imgBytesIn, string filePathIncludeName)
        {
            MemoryStream ms = new MemoryStream(imgBytesIn);

            Bitmap bmp = new Bitmap(ms);
            bmp.Save(filePathIncludeName, ImageFormat.Bmp);
            ms.Close();
        }





        /// <summary>
        /// 图像缩略图处理，无损压缩图片
        /// </summary>
        /// <param name="bytes">图像源数据</param>
        /// <param name="compression">压缩质量 1-100</param>
        /// <param name="thumbWidth">缩略图的宽</param>
        /// <param name="thumbHeight">缩略图的高</param>
        /// <returns></returns>
        public static byte[] ConvertToThumbnail(byte[] bytes, int compression = 100, int thumbWidth = 0, int thumbHeight = 0)
        {
            byte[] bs = null;

            try
            {
                if (bytes != null)
                {
                    using (MemoryStream ms = new MemoryStream(bytes))
                    {
                        using (Bitmap srcimg = new Bitmap(ms))
                        {
                            if (thumbWidth == 0 && thumbHeight == 0)
                            {
                                thumbWidth = srcimg.Width;
                                thumbHeight = srcimg.Height;
                            }
                            using (Bitmap dstimg = new Bitmap(thumbWidth, thumbHeight))//图片压缩质量
                            {
                                //从Bitmap创建一个System.Drawing.Graphics对象，用来绘制高质量的缩小图。
                                using (Graphics gr = Graphics.FromImage(dstimg))
                                {
                                    //把原始图像绘制成上面所设置宽高的缩小图
                                    Rectangle rectDestination = new Rectangle(0, 0, thumbWidth, thumbHeight);
                                    gr.Clear(Color.WhiteSmoke);
                                    gr.CompositingQuality = CompositingQuality.HighQuality;
                                    gr.SmoothingMode = SmoothingMode.HighQuality;
                                    gr.InterpolationMode = InterpolationMode.HighQualityBicubic;
                                    gr.DrawImage(srcimg, rectDestination, 0, 0, srcimg.Width, srcimg.Height, GraphicsUnit.Pixel);

                                    EncoderParameters ep = new EncoderParameters(1);
                                    ep.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, compression);//设置压缩的比例1-100
                                    ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();
                                    ImageCodecInfo jpegICIinfo = arrayICI.FirstOrDefault(t => t.FormatID == System.Drawing.Imaging.ImageFormat.Png.Guid);
                                    using (MemoryStream dstms = new MemoryStream())
                                    {
                                        if (jpegICIinfo != null)
                                        {
                                            dstimg.Save(dstms, jpegICIinfo, ep);
                                        }
                                        else
                                        {
                                            dstimg.Save(dstms, System.Drawing.Imaging.ImageFormat.Png);//保存到内存里
                                        }
                                        bs = new Byte[dstms.Length];
                                        dstms.Position = 0;
                                        dstms.Read(bs, 0, bs.Length);
                                    }
                                }
                            }
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                //LogManager.DefaultLogger.Error(LogConvert.ParseWebEx(ex), string.Concat("ConvertToThumbnail error.", thumbWidth, " ", thumbHeight));
            }
            return bs;
        }


    }

然后调用：

byte[] bys = DoPic.SaveImage(System.AppDomain.CurrentDomain.BaseDirectory + "timg.png");    //得到图片的Byte数组数据


byte[] newPic = DoPic.ConvertToThumbnail(bys, 1, 30, 30);     //将图片进行压缩


DoPic.ShowImgByByte(newPic, "E:\a.png");          //重新将新的图片保存