这里的问题是，嵌入的图像不是简单的
BMP或
JPEG。那是个
Microsoft Word Picture
并且OLE标头信息比原始
GetImageBytesFromOLEField()代码的300字节窗口大得多。（也就是说，在扫描300个字节后，它只是放弃了“无法确定标头大小…”。）
以下是该代码在其自己的类中的更新版本。课程测试包括提供的
Microsoft Word Picture，简单的
BMP和简单的
JPEG。
using System;using System.Collections.Generic;using System.Linq;namespace OleImageTest{ public static class OleImageUnwrap { public static byte[] GetImageBytesFromOLEField(byte[] oleFieldBytes) { // adapted from http://blogs.msdn.com/b/pranab/archive/2008/07/15/removing-ole-header-from-images-stored-in-ms-access-db-as-ole-object.aspx const int maxNumberOfBytesToSearch = 10000; byte[] imageBytes; // return value var imageSignatures = new List<byte[]>(); // PNG_ID_BLOCK = "x89PNGrnx1an" imageSignatures.Add(new byte[] { 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A }); // JPG_ID_BLOCK = "xFFxD8xFF" imageSignatures.Add(new byte[] { 0xFF, 0xD8, 0xFF }); // GIF_ID_BLOCK = "GIF8" imageSignatures.Add(new byte[] { 0x47, 0x49, 0x46, 0x38 }); // TIFF_ID_BLOCK = "II*x00" imageSignatures.Add(new byte[] { 0x49, 0x49, 0x2A, 0x00 }); // BITMAP_ID_BLOCK = "BM" imageSignatures.Add(new byte[] { 0x42, 0x4D }); int numberOfBytesToSearch = (oleFieldBytes.Count() < maxNumberOfBytesToSearch ? oleFieldBytes.Count() : maxNumberOfBytesToSearch); var startingBytes = new byte[numberOfBytesToSearch]; Array.Copy(oleFieldBytes, startingBytes, numberOfBytesToSearch); var positions = new List<int>(); foreach (byte[] blockSignature in imageSignatures) { positions = startingBytes.IndexOfSequence(blockSignature, 0); if (positions.Count > 0) { break; } } int iPos = -1; if (positions.Count > 0) { iPos = positions[0]; } if (iPos == -1) throw new Exception("Unable to determine header size for the OLE Object"); imageBytes = new byte[oleFieldBytes.LongLength - iPos]; System.IO.MemoryStream ms = new System.IO.MemoryStream(); ms.Write(oleFieldBytes, iPos, oleFieldBytes.Length - iPos); imageBytes = ms.ToArray(); ms.Close(); ms.Dispose(); return imageBytes; } private static List<int> IndexOfSequence(this byte[] buffer, byte[] pattern, int startIndex) { // ref: http://stackoverflow.com/a/332667/2144390 List<int> positions = new List<int>(); int i = Array.IndexOf<byte>(buffer, pattern[0], startIndex); while (i >= 0 && i <= buffer.Length - pattern.Length) { byte[] segment = new byte[pattern.Length]; Buffer.BlockCopy(buffer, i, segment, 0, pattern.Length); if (segment.SequenceEqual<byte>(pattern)) positions.Add(i); i = Array.IndexOf<byte>(buffer, pattern[0], i + 1); } return positions; } }}
