C# 使用原生环境对图片进行压缩

以下代码将会返回System.Drawing.Image，请在调用时输入文件路径，目标质量（1-100）。

        public System.Drawing.Image compressImage(string fileName,int newQuality) 
        {
            using (System.Drawing.Image image = System.Drawing.Image.FromFile(fileName))
            using (System.Drawing.Image memImage = new Bitmap(image, image.Width, image.Height)) //如果需要自定义长宽，请把参数提取至构造方法
            {
                ImageCodecInfo myImageCodecInfo;
                System.Drawing.Imaging.Encoder myEncoder;
                EncoderParameter myEncoderParameter;
                EncoderParameters myEncoderParameters;
                myImageCodecInfo = GetEncoderInfo("image/jpeg");
                myEncoder = System.Drawing.Imaging.Encoder.Quality;
                myEncoderParameters = new EncoderParameters(1);
                myEncoderParameter = new EncoderParameter(myEncoder, newQuality);
                myEncoderParameters.Param[0] = myEncoderParameter;

                MemoryStream memStream = new MemoryStream();
                memImage.Save(memStream, myImageCodecInfo, myEncoderParameters);
                System.Drawing.Image newImage = System.Drawing.Image.FromStream(memStream);
                ImageAttributes imageAttributes = new ImageAttributes();
                using (Graphics g = Graphics.FromImage(newImage))
                {
                    g.InterpolationMode =
                      System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;  //**
                    g.DrawImage(newImage, new Rectangle(System.Drawing.Point.Empty, newImage.Size), 0, 0,
                      newImage.Width, newImage.Height, GraphicsUnit.Pixel, imageAttributes);
                }
                return newImage;
            }
        }

        private static ImageCodecInfo GetEncoderInfo(String mimeType)
        {
            ImageCodecInfo[] encoders;
            encoders = ImageCodecInfo.GetImageEncoders();
            foreach (ImageCodecInfo ici in encoders)
                if (ici.MimeType == mimeType) return ici;

            return null;
        }

如果有别的需求，请将构造方法替换，例如直接输入Image对象或修改输出长宽。