C# 无损压缩图片
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1 //命名空间 2 using System.Drawing.Imaging; 3 using System.Drawing; 4 using System.Drawing.Drawing2D; 5 6 /// <summary> 7 /// 无损压缩图片 8 /// </summary> 9 /// <param name="sFile">原图片</param> 10 /// <param name="dFile">压缩后保存位置</param> 11 /// <param name="dHeight">高度</param> 12 /// <param name="dWidth"></param> 13 /// <param name="flag">压缩质量 1-100</param> 14 /// <returns></returns> 15 public static bool GetPicThumbnail(string sFile, string dFile, int dHeight, int dWidth, int flag) 16 { 17 18 System.Drawing.Image iSource = System.Drawing.Image.FromFile(sFile); 19 ImageFormat tFormat = iSource.RawFormat; 20 int sW = 0, sH = 0; 21 //按比例缩放 22 Size tem_size = new Size(iSource.Width, iSource.Height); 23 24 if (tem_size.Width > dHeight||tem_size.Width > dWidth) 25 { 26 if ((tem_size.Width * dHeight) > (tem_size.Height * dWidth)) 27 { 28 sW = dWidth; 29 sH = (dWidth * tem_size.Height) / tem_size.Width; 30 } 31 else 32 { 33 sH = dHeight; 34 sW = (tem_size.Width * dHeight) / tem_size.Height; 35 } 36 } 37 else 38 { 39 sW = tem_size.Width; 40 sH = tem_size.Height; 41 } 42 Bitmap ob = new Bitmap(dWidth, dHeight); 43 Graphics g = Graphics.FromImage(ob); 44 g.Clear(Color.WhiteSmoke); 45 g.CompositingQuality = CompositingQuality.HighQuality; 46 g.SmoothingMode = SmoothingMode.HighQuality; 47 g.InterpolationMode = InterpolationMode.HighQualityBicubic; 48 g.DrawImage(iSource, new Rectangle((dWidth - sW) / 2, (dHeight - sH) / 2, sW, sH), 0, 0, iSource.Width, iSource.Height, GraphicsUnit.Pixel); 49 g.Dispose(); 50 //以下代码为保存图片时，设置压缩质量 51 EncoderParameters ep = new EncoderParameters(); 52 long[] qy = new long[1]; 53 qy[0] = flag;//设置压缩的比例1-100 54 EncoderParameter eParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, qy); 55 ep.Param[0] = eParam; 56 try 57 { 58 ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders(); 59 ImageCodecInfo jpegICIinfo = null; 60 for (int x = 0; x < arrayICI.Length; x++) 61 { 62 if (arrayICI[x].FormatDescription.Equals("JPEG")) 63 { 64 jpegICIinfo = arrayICI[x]; 65 break; 66 } 67 } 68 if (jpegICIinfo != null) 69 { 70 ob.Save(dFile, jpegICIinfo, ep);//dFile是压缩后的新路径 71 } 72 else 73 { 74 ob.Save(dFile, tFormat); 75 } 76 return true; 77 } 78 catch 79 { 80 return false; 81 } 82 finally 83 { 84 iSource.Dispose(); 85 ob.Dispose(); 86 } 87 88 }
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