C# 生成缩略图 去除图片旋转角度
图片生成缩略图会有旋转角度
/// <summary> /// 测试JRE图片压缩后图片会旋转问题 /// </summary> public void Uploadimg1() { HttpPostedFile hpf = HttpContext.Current.Request.Files[0]; var context = HttpContext.Current; string newurl = context.Server.MapPath("/upload/img/" + DateTime.Now.ToString("yyyyMM") + "/"); string newfilename = hpf.FileName; hpf.SaveAs(newurl + "_" + newfilename); hpf.SaveAs(newurl + newfilename); JREUpLoadImage(hpf, newurl, "sm_", 244, 165, newfilename); File.Delete(newurl + "_" + newfilename); } /// <summary> /// 生成缩略图 /// </summary> /// <param name="upImage"></param> /// <param name="sSavePath"></param> /// <param name="sThumbExtension"></param> /// <param name="intThumbWidth"></param> /// <param name="intThumbHeight"></param> /// <param name="filename"></param> private void JREUpLoadImage(HttpPostedFile upImage, string sSavePath, string sThumbExtension, int intThumbWidth, int intThumbHeight, string filename) { string sThumbFile = ""; string sFilename = filename; int nFileLen = upImage.ContentLength; string extendName = System.IO.Path.GetExtension(upImage.FileName).ToLower(); byte[] myData = new Byte[nFileLen]; upImage.InputStream.Read(myData, 0, nFileLen); sFilename = System.IO.Path.GetFileName(filename); int file_append = 0; //以上为上传原图 try { //原图加载 using (Image sourceImage = Image.FromFile(sSavePath + sFilename)) { //旋转图片 RotateImage(sourceImage); //原图宽度和高度 int width = sourceImage.Width; int height = sourceImage.Height; int smallWidth; int smallHeight; //获取第一张绘制图的大小,(比较 原图的宽/缩略图的宽 和 原图的高/缩略图的高) if ((decimal)width / intThumbWidth <= ((decimal)height) / intThumbHeight) { smallWidth = width * intThumbHeight / height; smallHeight = intThumbHeight; } else { smallWidth = intThumbWidth; smallHeight = height * intThumbWidth / width; } //判断缩略图在当前文件夹下是否同名称文件存在 file_append = 0; sThumbFile = sThumbExtension + sFilename; while (System.IO.File.Exists(sSavePath + sThumbFile)) { file_append++; sThumbFile = sThumbExtension + System.IO.Path.GetFileNameWithoutExtension(upImage.FileName) + file_append.ToString() + ".jpg"; } //缩略图保存的绝对路径 string smallImagePath = sSavePath + sThumbFile; //新建一个图板,以最小等比例压缩大小绘制原图 using (Image bitmap = new Bitmap(smallWidth, smallHeight)) { //绘制中间图 using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap)) { //高清,平滑 g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; g.Clear(Color.Black); g.DrawImage( sourceImage, new System.Drawing.Rectangle(0, 0, smallWidth, smallHeight), new System.Drawing.Rectangle(0, 0, width, height), System.Drawing.GraphicsUnit.Pixel ); } //新建一个图板,以缩略图大小绘制中间图 using (System.Drawing.Image bitmap1 = new System.Drawing.Bitmap(intThumbWidth, intThumbHeight)) { //绘制缩略图 using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap1)) { //高清,平滑 g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; g.Clear(Color.Black); int lwidth = (smallWidth - intThumbWidth) / 2; int bheight = (smallHeight - intThumbHeight) / 2; g.DrawImage(bitmap, new Rectangle(0, 0, intThumbWidth, intThumbHeight), lwidth, bheight, intThumbWidth, intThumbHeight, GraphicsUnit.Pixel); g.Dispose(); bitmap.Save(smallImagePath, System.Drawing.Imaging.ImageFormat.Jpeg); } } } } } catch { //出错则删除 System.IO.File.Delete(sSavePath + sFilename); } } /// <summary> /// 旋转图片 /// </summary> /// <param name="img"></param> private void RotateImage(Image img) { var exif = ReadExif(img); if (exif.ContainsKey("Orientation")) { switch (int.Parse(exif["Orientation"])) { case 2: img.RotateFlip(RotateFlipType.RotateNoneFlipX);//horizontal flip break; case 3: img.RotateFlip(RotateFlipType.Rotate180FlipNone);//right-top //img = Rotate((Bitmap)img, 180); break; case 4: img.RotateFlip(RotateFlipType.RotateNoneFlipY);//vertical flip break; case 5: img.RotateFlip(RotateFlipType.Rotate90FlipX); break; case 6: img.RotateFlip(RotateFlipType.Rotate90FlipNone);//right-top break; case 7: img.RotateFlip(RotateFlipType.Rotate270FlipX); break; case 8: img.RotateFlip(RotateFlipType.Rotate270FlipNone);//left-bottom break; } } } /// <summary> /// 获取图片旋转角度 /// </summary> /// <param name="image"></param> /// <returns></returns> private Dictionary<string, string> ReadExif(Image image) { var exif = new Dictionary<string, string>(); var properties = image.PropertyItems; foreach (var property in properties) { switch (property.Id) { case 0x010E: exif["ImageTitle"] = ASCIIToString(property.Value); break; case 0x010F: exif["Make"] = ASCIIToString(property.Value); break; case 0x0110: exif["Model"] = ASCIIToString(property.Value); break; case 0x0112: exif["Orientation"] = ShortToString(property.Value, 0); break; case 0x011A: exif["XResolution"] = RationalToSingle(property.Value, 0); break; case 0x011B: exif["YResolution"] = RationalToSingle(property.Value, 0); break; case 0x0128: exif["ResolutionUnit"] = ShortToString(property.Value, 0); break; case 0x0131: exif["Software"] = ASCIIToString(property.Value); break; case 0x0132: exif["DateTime"] = ASCIIToString(property.Value); break; //GPS case 0x0002: exif["GPSLatitude"] = string.Format("{0}°{1}′{2}″", RationalToSingle(property.Value, 0), RationalToSingle(property.Value, 8), RationalToSingle(property.Value, 16) ); break; case 0x0004: exif["GPSLongitude"] = string.Format("{0}°{1}′{2}″", RationalToSingle(property.Value, 0), RationalToSingle(property.Value, 8), RationalToSingle(property.Value, 16) ); break; case 0x0006: exif["GPSAltitude"] = RationalToSingle(property.Value, 0); break; } } return exif; } string ByteToString(byte[] b, int startindex) { if (startindex + 1 <= b.Length) return ((char)b[startindex]).ToString(); else return string.Empty; } string ShortToString(byte[] b, int startindex) { if (startindex + 2 <= b.Length) return BitConverter.ToInt16(b, startindex).ToString(); else return string.Empty; } string RationalToSingle(byte[] b, int startindex) { if (startindex + 8 <= b.Length) return (BitConverter.ToSingle(b, startindex) / BitConverter.ToSingle(b, startindex + 4)).ToString(); else return string.Empty; } string ASCIIToString(byte[] b) { return Encoding.ASCII.GetString(b); }
