/// <summary> /// 无损压缩图片 /// </summary> /// <param name="content">base64字节流</param> /// <param name="flag">(数字越小压缩率越高)1-100</param> /// <param name="size">压缩后图片的最大大小</param> /// <param name="sfsc">是否是第一次调用</param> /// <returns></returns> public static string CompressImage(string content, int flag = 90, int size = 500, bool sfsc = true) { //如果是第一次调用,原始图像的大小小于要压缩的大小,则直接复制文件,并且返回true byte[] bytes = Convert.FromBase64String(content); if (sfsc == true && bytes.Length < size * 1024) { return content; } MemoryStream stream = new MemoryStream(bytes, 0, bytes.Length); stream.Write(bytes, 0, bytes.Length); Image iSource = Image.FromStream(stream); ImageFormat tFormat = iSource.RawFormat; int dHeight = iSource.Height / 2; int dWidth = iSource.Width / 2; //按比例缩放 Size tem_size = new Size(iSource.Width, iSource.Height); int sH; int sW; if (tem_size.Width > dHeight || tem_size.Width > dWidth) { if ((tem_size.Width * dHeight) > (tem_size.Width * dWidth)) { sW = dWidth; sH = (dWidth * tem_size.Height) / tem_size.Width; } else { sH = dHeight; sW = (tem_size.Width * dHeight) / tem_size.Height; } } else { sW = tem_size.Width; sH = tem_size.Height; } Bitmap ob = new Bitmap(dWidth, dHeight); Graphics g = Graphics.FromImage(ob); g.Clear(Color.WhiteSmoke); g.CompositingQuality =CompositingQuality.HighQuality; g.SmoothingMode = SmoothingMode.HighQuality; g.InterpolationMode =InterpolationMode.HighQualityBicubic; g.DrawImage(iSource, new Rectangle((dWidth - sW) / 2, (dHeight - sH) / 2, sW, sH), 0, 0, iSource.Width, iSource.Height, GraphicsUnit.Pixel); g.Dispose(); //以下代码为保存图片时,设置压缩质量 EncoderParameters ep = new EncoderParameters(); long[] qy = new long[1]; qy[0] = flag;//设置压缩的比例1-100 EncoderParameter eParam = new EncoderParameter(Encoder.Quality, qy); ep.Param[0] = eParam; //保存在内存流 MemoryStream ms = new MemoryStream(); ms.Position = 0; string imagebase64 = ""; try { ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders(); ImageCodecInfo jpegICIinfo = null; for (int x = 0; x < arrayICI.Length; x++) { if (arrayICI[x].FormatDescription.Equals("JPEG")) { jpegICIinfo = arrayICI[x]; break; } } if (jpegICIinfo != null) { ob.Save(ms, jpegICIinfo, ep); byte[] arr = new byte[ms.Length]; ms.Read(arr, 0, (int)ms.Length); imagebase64 = Convert.ToBase64String(arr); if (arr.Length > 1024 * size) { flag -= 10; CompressImage(content, flag, size, false); } } else { ob.Save(ms, tFormat); byte[] arr = new byte[ms.Length]; ms.Read(arr, 0, (int)ms.Length); imagebase64 = Convert.ToBase64String(bytes); } return imagebase64; } catch { return imagebase64; } finally { iSource.Dispose(); ob.Dispose(); ms.Close(); stream.Close(); } }
写的不咋地,但是能用了。。嘿