示例#1
0
        /// <summary>
        /// Reads the APP1 section containing Exif metadata.
        /// </summary>
        private void ReadAPP1()
        {
            // Find the APP1 section containing Exif metadata
            app1 = file.Sections.Find(a => (a.Marker == JPEGMarker.APP1) &&
                                      (Encoding.ASCII.GetString(a.Header, 0, 6) == "Exif\0\0"));

            // If there is no APP1 section, add a new one after the last APP0 section (if any).
            if (app1 == null)
            {
                int insertionIndex = file.Sections.FindLastIndex(a => a.Marker == JPEGMarker.APP0);
                if (insertionIndex == -1)
                {
                    insertionIndex = 0;
                }
                insertionIndex++;
                ByteOrder = BitConverterEx.ByteOrder.BigEndian;
                app1      = new JPEGSection(JPEGMarker.APP1);
                file.Sections.Insert(insertionIndex, app1);
                return;
            }
#if DEBUG
            mMap = new MemoryBinStream();
            mMap.Seek(0, SeekOrigin.Begin);
            mMap.Write(new Bin("Exif Marker", 3, 6));
#endif

            byte[] header = app1.Header;
            SortedList <int, IFD> ifdqueue = new SortedList <int, IFD>();
            makerNoteOffset = 0;

            // TIFF header
            int tiffoffset = 6;
            if (header[tiffoffset] == 0x49)
            {
                ByteOrder = BitConverterEx.ByteOrder.LittleEndian;
            }
            else
            {
                ByteOrder = BitConverterEx.ByteOrder.BigEndian;
            }
            BitConverterEx conv = new BitConverterEx(ByteOrder, BitConverterEx.ByteOrder.System);

            // Offset to 0th IFD
            int ifd0offset = (int)conv.ToUInt32(header, tiffoffset + 4);
            ifdqueue.Add(ifd0offset, IFD.Zeroth);

            int thumboffset = -1;
            int thumblength = 0;
            int thumbtype   = -1;
#if DEBUG
            mMap.Write(new Bin("Byte Order: " + ByteOrder.ToString(), 4, 2));
            mMap.Write(new Bin("TIFF ID: 0x00, 0x2A", 4, 2));
            mMap.Write(new Bin("Offset to 0th IFD: " + ifd0offset.ToString(), 4, 4));
#endif
            // Read IFDs
            while (ifdqueue.Count != 0)
            {
                int ifdoffset  = tiffoffset + ifdqueue.Keys[0];
                IFD currentifd = ifdqueue.Values[0];
                ifdqueue.RemoveAt(0);

                // Field count
                ushort fieldcount = conv.ToUInt16(header, ifdoffset);
#if DEBUG
                mMap.Seek(ifdoffset, SeekOrigin.Begin);
                mMap.Write(new Bin(currentifd.ToString() + " IFD Field Count: " + fieldcount.ToString(), 5, 2));
#endif
                for (short i = 0; i < fieldcount; i++)
                {
                    // Read field info
                    int    fieldoffset = ifdoffset + 2 + 12 * i;
                    ushort tag         = conv.ToUInt16(header, fieldoffset);
                    ushort type        = conv.ToUInt16(header, fieldoffset + 2);
                    uint   count       = conv.ToUInt32(header, fieldoffset + 4);
                    byte[] value       = new byte[4];
                    Array.Copy(header, fieldoffset + 8, value, 0, 4);

                    // Fields containing offsets to other IFDs
                    if (currentifd == IFD.Zeroth && tag == 0x8769)
                    {
                        int exififdpointer = (int)conv.ToUInt32(value, 0);
                        ifdqueue.Add(exififdpointer, IFD.EXIF);
                    }
                    else if (currentifd == IFD.Zeroth && tag == 0x8825)
                    {
                        int gpsifdpointer = (int)conv.ToUInt32(value, 0);
                        ifdqueue.Add(gpsifdpointer, IFD.GPS);
                    }
                    else if (currentifd == IFD.EXIF && tag == 0xa005)
                    {
                        int interopifdpointer = (int)conv.ToUInt32(value, 0);
                        ifdqueue.Add(interopifdpointer, IFD.Interop);
                    }

                    // Save the offset to maker note data
                    if (currentifd == IFD.EXIF && tag == 37500)
                    {
                        makerNoteOffset = conv.ToUInt32(value, 0);
                    }

                    // Calculate the bytes we need to read
                    uint baselength = 0;
                    if (type == 1 || type == 2 || type == 7)
                    {
                        baselength = 1;
                    }
                    else if (type == 3)
                    {
                        baselength = 2;
                    }
                    else if (type == 4 || type == 9)
                    {
                        baselength = 4;
                    }
                    else if (type == 5 || type == 10)
                    {
                        baselength = 8;
                    }
                    uint totallength = count * baselength;

                    // If field value does not fit in 4 bytes
                    // the value field is an offset to the actual
                    // field value
                    int fieldposition = 0;
                    if (totallength > 4)
                    {
                        fieldposition = tiffoffset + (int)conv.ToUInt32(value, 0);
                        value         = new byte[totallength];
                        Array.Copy(header, fieldposition, value, 0, totallength);
                    }

                    // Compressed thumbnail data
                    if (currentifd == IFD.First && tag == 0x201)
                    {
                        thumbtype   = 0;
                        thumboffset = (int)conv.ToUInt32(value, 0);
                    }
                    else if (currentifd == IFD.First && tag == 0x202)
                    {
                        thumblength = (int)conv.ToUInt32(value, 0);
                    }

                    // Uncompressed thumbnail data
                    if (currentifd == IFD.First && tag == 0x111)
                    {
                        thumbtype = 1;
                        // Offset to first strip
                        if (type == 3)
                        {
                            thumboffset = (int)conv.ToUInt16(value, 0);
                        }
                        else
                        {
                            thumboffset = (int)conv.ToUInt32(value, 0);
                        }
                    }
                    else if (currentifd == IFD.First && tag == 0x117)
                    {
                        thumblength = 0;
                        for (int j = 0; j < count; j++)
                        {
                            if (type == 3)
                            {
                                thumblength += (int)conv.ToUInt16(value, 0);
                            }
                            else
                            {
                                thumblength += (int)conv.ToUInt32(value, 0);
                            }
                        }
                    }

                    // Create the exif property from the interop data
                    ExifProperty prop = ExifPropertyFactory.Get(tag, type, count, value, ByteOrder, currentifd);
                    Properties.Add(prop.Tag, prop);
#if DEBUG
                    mMap.Seek(fieldoffset, SeekOrigin.Begin);
                    mMap.Write(new Bin(ExifTagFactory.GetTagName(currentifd, tag) + " ID: " + tag.ToString(), 6, 2, prop));
                    mMap.Write(new Bin(ExifTagFactory.GetTagName(currentifd, tag) + " Type: " + type.ToString(), 6, 2, prop));
                    mMap.Write(new Bin(ExifTagFactory.GetTagName(currentifd, tag) + " Count: " + count.ToString(), 6, 4, prop));
                    mMap.Write(new Bin(ExifTagFactory.GetTagName(currentifd, tag) + " Value: " + string.Format("[0x{0:x2}, 0x{1:x2}, 0x{2:x2}, 0x{3:x2}]", value[0], value[1], value[2], value[3]), 6, 4, prop));
                    if (totallength > 4)
                    {
                        mMap.Seek(fieldposition, SeekOrigin.Begin);
                        mMap.Write(new Bin(ExifTagFactory.GetTagName(currentifd, tag) + " Data", 7, totallength, prop));
                    }
#endif
                }

                // 1st IFD pointer
                int firstifdpointer = (int)conv.ToUInt32(header, ifdoffset + 2 + 12 * fieldcount);
                if (firstifdpointer != 0)
                {
                    ifdqueue.Add(firstifdpointer, IFD.First);
                }
#if DEBUG
                mMap.Seek(ifdoffset + 2 + 12 * fieldcount, SeekOrigin.Begin);
                mMap.Write(new Bin("1st IFD Pointer: " + firstifdpointer.ToString(), 5, 4));
#endif
                // Read thumbnail
                if (thumboffset != -1 && thumblength != 0 && Thumbnail == null)
                {
                    if (thumbtype == 0)
                    {
                        using (MemoryStream ts = new MemoryStream(header, tiffoffset + thumboffset, thumblength))
                        {
                            Thumbnail = new JPEGFile(ts);
                        }
                    }
#if DEBUG
                    mMap.Seek(tiffoffset + thumboffset, SeekOrigin.Begin);
                    mMap.Write(new Bin("Thumbnail", 8, thumblength));
#endif
                }
            }
        }
示例#2
0
        /// <summary>
        /// Reads the given stream.
        /// </summary>
        /// <param name="stream">The data stream used to load the image.</param>
        /// <exception cref="NotValidJPEGFileException"></exception>
        private void Read(Stream stream)
        {
            Sections = new List <JPEGSection>();

            using (stream)
            {
                // Read the Start of Image (SOI) marker. SOI marker is represented
                // with two bytes: 0xFF, 0xD8.
                byte[] markerbytes = new byte[2];
                if (stream.Read(markerbytes, 0, 2) != 2 || markerbytes[0] != 0xFF && markerbytes[1] != 0xD8)
                {
                    throw new NotValidJPEGFileException();
                }
                stream.Seek(0, SeekOrigin.Begin);

                // Search and read sections until we reach the end of file.
                while (stream.Position != stream.Length)
                {
                    // Read the next section marker. Section markers are two bytes
                    // with values 0xFF, 0x?? where ?? must not be 0x00 or 0xFF.
                    if (stream.Read(markerbytes, 0, 2) != 2 || markerbytes[0] != 0xFF || markerbytes[1] == 0x00 || markerbytes[1] == 0xFF)
                    {
                        throw new NotValidJPEGFileException();
                    }

                    JPEGMarker marker = (JPEGMarker)markerbytes[1];

                    byte[] header = new byte[0];
                    // SOI, EOI and RST markers do not contain any header
                    if (marker != JPEGMarker.SOI && marker != JPEGMarker.EOI && !(marker >= JPEGMarker.RST0 && marker <= JPEGMarker.RST7))
                    {
                        // Length of the header including the length bytes.
                        // This value is a 16-bit unsigned integer
                        // in big endian byte-order.
                        byte[] lengthbytes = new byte[2];
                        if (stream.Read(lengthbytes, 0, 2) != 2)
                        {
                            throw new NotValidJPEGFileException();
                        }
                        long length = (long)BitConverterEx.BigEndian.ToUInt16(lengthbytes, 0);

                        // Read section header.
                        header = new byte[length - 2];
                        int bytestoread = header.Length;
                        while (bytestoread > 0)
                        {
                            int count     = Math.Min(bytestoread, 4 * 1024);
                            int bytesread = stream.Read(header, header.Length - bytestoread, count);
                            if (bytesread == 0)
                            {
                                throw new NotValidJPEGFileException();
                            }
                            bytestoread -= bytesread;
                        }
                    }

                    // Start of Scan (SOS) sections and RST sections are immediately
                    // followed by entropy coded data. For that, we need to read until
                    // the next section marker once we reach a SOS or RST.
                    byte[] entropydata = new byte[0];
                    if (marker == JPEGMarker.SOS || (marker >= JPEGMarker.RST0 && marker <= JPEGMarker.RST7))
                    {
                        long position = stream.Position;

                        // Search for the next section marker
                        while (true)
                        {
                            // Search for an 0xFF indicating start of a marker
                            int nextbyte = 0;
                            do
                            {
                                nextbyte = stream.ReadByte();
                                if (nextbyte == -1)
                                {
                                    throw new NotValidJPEGFileException();
                                }
                            } while ((byte)nextbyte != 0xFF);

                            // Skip filler bytes (0xFF)
                            do
                            {
                                nextbyte = stream.ReadByte();
                                if (nextbyte == -1)
                                {
                                    throw new NotValidJPEGFileException();
                                }
                            } while ((byte)nextbyte == 0xFF);

                            // Looks like a section marker. The next byte must not be 0x00.
                            if ((byte)nextbyte != 0x00)
                            {
                                // We reached a section marker. Calculate the
                                // length of the entropy coded data.
                                stream.Seek(-2, SeekOrigin.Current);
                                long edlength = stream.Position - position;
                                stream.Seek(-edlength, SeekOrigin.Current);

                                // Read entropy coded data
                                entropydata = new byte[edlength];
                                int bytestoread = entropydata.Length;
                                while (bytestoread > 0)
                                {
                                    int count     = Math.Min(bytestoread, 4 * 1024);
                                    int bytesread = stream.Read(entropydata, entropydata.Length - bytestoread, count);
                                    if (bytesread == 0)
                                    {
                                        throw new NotValidJPEGFileException();
                                    }
                                    bytestoread -= bytesread;
                                }

                                break;
                            }
                        }
                    }

                    // Store section.
                    JPEGSection section = new JPEGSection(marker, header, entropydata);
                    Sections.Add(section);

                    // Some propriety formats store data past the EOI marker
                    if (marker == JPEGMarker.EOI)
                    {
                        int bytestoread = (int)(stream.Length - stream.Position);
                        TrailingData = new byte[bytestoread];
                        while (bytestoread > 0)
                        {
                            int count     = (int)Math.Min(bytestoread, 4 * 1024);
                            int bytesread = stream.Read(TrailingData, TrailingData.Length - bytestoread, count);
                            if (bytesread == 0)
                            {
                                throw new NotValidJPEGFileException();
                            }
                            bytestoread -= bytesread;
                        }
                    }
                }
                stream.Close();
            }
        }