在窗体中显示dwg格式缩略图

菜鸟还是菜鸟,本人下午忙活了半天,终于皇天不付有心人哈哈,能在winform窗体中实现这个功能.实现缩略图的类是网上面找来的,晚上回去好好消化掉先!~()

重要的两个类: public static Image GetThumbnail(string dwgFilePath) { if (!(File.Exists(dwgFilePath))) { return null; } FileStream dwgStream = null; BinaryReader dwgReader = null; MemoryStream bmpStream = new MemoryStream(); BinaryWriter bmpWriter = new BinaryWriter(bmpStream); try { dwgStream = new FileStream(dwgFilePath, FileMode.Open, FileAccess.Read); dwgReader = new BinaryReader(dwgStream); dwgStream.Seek(13, SeekOrigin.Begin); //从第十三字节开始读取 int dwgDescPos = dwgReader.ReadInt32(); //第13到17字节指示缩略图描述块的位置 dwgStream.Seek(dwgDescPos + 30, SeekOrigin.Begin); //将指针移到缩略图描述块的第31字节 int typePreview = dwgReader.ReadByte(); //第31字节为缩略图格式信息，2 为BMP格式，3为WMF格式 if (typePreview == 2 || typePreview == 3) { int bihPos = dwgReader.ReadInt32(); //BIH int bmpLen = dwgReader.ReadInt32(); //位图大小 dwgStream.Seek(bihPos + 14, SeekOrigin.Begin); //跳过BIH前14字节到biBitCount if (dwgReader.ReadInt16() != 8) //biBitCount != 8 { return null; } dwgStream.Seek(bihPos, SeekOrigin.Begin); byte[] bmpData = dwgReader.ReadBytes(bmpLen); //包含在DWG文件中的BMP数据，从BIH开始 bmpWriter.Write((short)19778); //BFH.bfType : 'BM', 4bytes bmpWriter.Write(0L); //BFH.bfSize, BFH.bfReserved : 0, 8bytes bmpWriter.Write(1078); //BFH.bfOffBits : BFH + BIH + Color Table = 14 + 40 + 1024, 4bytes bmpWriter.Write(SwapBlackAndWhiteInColorTable(bmpData)); bmpStream.Seek(0, SeekOrigin.Begin); return Image.FromStream(bmpStream); } return null; } catch (Exception) { return null; } finally { if (dwgReader != null) { dwgReader.Close(); } if (dwgStream != null) { dwgStream.Close(); } bmpWriter.Close(); bmpStream.Close(); } } /// <summary> /// 黑白反色 /// </summary> /// <param name="bytes">Image描述内容的字节码</param> /// <returns>反色后的字节码</returns> private static byte[] SwapBlackAndWhiteInColorTable(byte[] bytes) { for (int i = 40; i < 1064; i += 4) { if (bytes[i] == 0 && bytes[i + 1] == 0 && bytes[i + 2] == 0) { bytes[i] = bytes[i + 1] = bytes[i + 2] = 0xFF; } else if (bytes[i] == 0xFF && bytes[i + 1] == 0xFF && bytes[i + 2] == 0xFF) { bytes[i] = bytes[i + 1] = bytes[i + 2] = 0; } } return bytes; }

,代码想写好的简单测试代码下载地址:http://www.objectarx.net/bbs/viewthread.php?tid=1502&highlight=%CB%F5%C2%D4%CD%BC!~

有做cad二次开发的大家来交流下心得....