图片压缩&图片裁剪

项目需要，需要讲图片(jpg,png,tif)裁剪压缩为80*80的文件

借助一位老前辈的代码，如下

        #region 正方型裁剪并缩放
        /// <summary>
        /// 正方型裁剪
        /// 以图片中心为轴心，截取正方型，然后等比缩放
        /// 用于头像处理
        /// </summary>
        /// <remarks></remarks>
        /// <param name="fromFile">原图Stream对象</param>
        /// <param name="fileSaveUrl">缩略图存放地址</param>
        /// <param name="side">指定的边长（正方型）</param>80
        /// <param name="quality">质量（范围0-100）</param>
        public static void CutForSquare(Stream fromFile, string fileSaveUrl, int side, int quality)
        {
            //创建目录
            string dir = Path.GetDirectoryName(fileSaveUrl);
            if (!Directory.Exists(dir))
                Directory.CreateDirectory(dir);

            //原始图片（获取原始图片创建对象，并使用流中嵌入的颜色管理信息）
            Image initImage = Image.FromStream(fromFile, true);

            //原图宽高均小于模版，不作处理，直接保存
            if (initImage.Width <= side && initImage.Height <= side)
            {
                initImage.Save(fileSaveUrl, ImageFormat.Jpeg);
            }
            else
            {
                //原始图片的宽、高
                int initWidth = initImage.Width;
                int initHeight = initImage.Height;

                //非正方型先裁剪为正方型
                if (initWidth != initHeight)
                {
                    //截图对象
                    Image pickedImage = null;
                    Graphics pickedG = null;

                    //宽大于高的横图
                    if (initWidth > initHeight)
                    {
                        //对象实例化
                        pickedImage = new Bitmap(initHeight, initHeight);
                        pickedG = Graphics.FromImage(pickedImage);
                        //设置质量
                        pickedG.InterpolationMode = InterpolationMode.HighQualityBicubic;
                        pickedG.SmoothingMode = SmoothingMode.HighQuality;
                        //定位
                        Rectangle fromR = new Rectangle((initWidth - initHeight) / 2, 0, initHeight, initHeight);
                        Rectangle toR = new Rectangle(0, 0, initHeight, initHeight);
                        //画图
                        pickedG.DrawImage(initImage, toR, fromR, GraphicsUnit.Pixel);
                        //重置宽
                        initWidth = initHeight;
                    }
                    //高大于宽的竖图
                    else
                    {
                        //对象实例化
                        pickedImage = new Bitmap(initWidth, initWidth);
                        pickedG = Graphics.FromImage(pickedImage);
                        //设置质量
                        pickedG.InterpolationMode = InterpolationMode.HighQualityBicubic;
                        pickedG.SmoothingMode = SmoothingMode.HighQuality;
                        //定位
                        Rectangle fromR = new Rectangle(0, (initHeight - initWidth) / 2, initWidth, initWidth);
                        Rectangle toR = new Rectangle(0, 0, initWidth, initWidth);
                        //画图
                        pickedG.DrawImage(initImage, toR, fromR, GraphicsUnit.Pixel);
                        //重置高
                        initHeight = initWidth;
                    }

                    //将截图对象赋给原图
                    initImage = (Image)pickedImage.Clone();
                    //释放截图资源
                    pickedG.Dispose();
                    pickedImage.Dispose();
                }

                //缩略图对象
                Image resultImage = new Bitmap(side, side);
                Graphics resultG = Graphics.FromImage(resultImage);
                //设置质量
                resultG.InterpolationMode = InterpolationMode.HighQualityBicubic;
                resultG.SmoothingMode = SmoothingMode.HighQuality;
                //用指定背景色清空画布
                resultG.Clear(Color.White);
                //绘制缩略图
                resultG.DrawImage(initImage, new Rectangle(0, 0, side, side), new Rectangle(0, 0, initWidth, initHeight), GraphicsUnit.Pixel);

                //关键质量控制
                //获取系统编码类型数组,包含了jpeg,bmp,png,gif,tiff
                ImageCodecInfo[] icis = ImageCodecInfo.GetImageEncoders();
                ImageCodecInfo ici = null;
                foreach (ImageCodecInfo i in icis)
                {
                    if (i.MimeType == "image/jpeg" || i.MimeType == "image/png" || i.MimeType == "image/tiff")
                    {
                        ici = i;
                    }
                }
                EncoderParameters ep = new EncoderParameters(1);
                ep.Param[0] = new EncoderParameter(Encoder.Quality, (long)quality);

                //保存缩略图
                resultImage.Save(fileSaveUrl, ici, ep);

                //释放关键质量控制所用资源
                ep.Dispose();

                //释放缩略图资源
                resultG.Dispose();
                resultImage.Dispose();

                //释放原始图片资源
                initImage.Dispose();
            }
        }
        #endregion

引用

using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;

参考来源：https://www.cnblogs.com/wanzhongjun/p/11070139.html