using System;using System.Collections.Generic;using System.Drawing;using System.Drawing.Drawing2D;using System.Drawing.Imaging;using System.IO;using System.Linq;using System.Text;using System.Threading.Tasks;namespace CompressImg{ public class CompressHelp { /// <summary> /// 无损压缩图片 /// </summary> /// <param name="sFile">文件位置</param> /// <param name="dFile">压缩后保存位置</param> /// <param name="flag">压缩比例，eg:按照百分比算如80，就是原图的高度乘以80%</param> /// <returns></returns> public bool GetPicThumbnail(string sFile, string dFile, int flag) { int size = 200;//设置图片压缩大小值以内 System.Drawing.Image iSource = System.Drawing.Image.FromFile(sFile); ImageFormat tFormat = iSource.RawFormat; int sW = 0, sH = 0; FileInfo dFiles = new FileInfo(dFile); //判断目录是否存在 if (!Directory.Exists(dFiles.DirectoryName)) { Directory.CreateDirectory(dFiles.DirectoryName); } FileInfo fileInfo = new FileInfo(sFile); //判断图片大小 if (fileInfo.Length <= 1024 * size) { fileInfo.CopyTo(dFile, true); return true; } //按比例缩放 Size tem_size = new Size(iSource.Width, iSource.Height); int dHeight = iSource.Height * flag / 100; //高度压缩百分不 int dWidth = iSource.Width * flag / 100;//宽度压缩百分比 if (tem_size.Width > dHeight || tem_size.Width > dWidth) //将**改成c#中的或者操作符号 { if ((tem_size.Width * dHeight) > (tem_size.Height * 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(System.Drawing.Imaging.Encoder.Quality, qy); ep.Param[0] = eParam; 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(dFile, jpegICIinfo, ep);//dFile是压缩后的新路径 FileInfo fi = new FileInfo(dFile); if (fi.Length > 1024 * size) { flag -= 10; GetPicThumbnail(sFile, dFile, flag); } } else { ob.Save(dFile, tFormat); } return true; } catch { return false; } finally { iSource.Dispose(); ob.Dispose(); } } }}