exiv2/src/image.cpp

// ***************************************************************** -*- C++ -*-
/*
 * Copyright (C) 2004 Andreas Huggel <ahuggel@gmx.net>
 * 
 * This program is part of the Exiv2 distribution.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */
/*
  File:      image.cpp
  Version:   $Name:  $ $Revision: 1.3 $
  Author(s): Andreas Huggel (ahu) <ahuggel@gmx.net>
  History:   26-Jan-04, ahu: created
             11-Feb-04, ahu: isolated as a component
 */
// *****************************************************************************
#include "rcsid.hpp"
EXIV2_RCSID("@(#) $Name:  $ $Revision: 1.3 $ $RCSfile: image.cpp,v $")

// *****************************************************************************
// included header files
#include "image.hpp"
#include "types.hpp"

// + standard includes
#include <iostream>
#include <fstream>
#include <cstring>
#include <cstdio>                               // for rename
#include <sys/types.h>                          // for getpid
#include <unistd.h>                             // for getpid, unlink

// *****************************************************************************
// class member definitions
namespace Exif {

    JpegImage::JpegImage()
        : sizeExifData_(0), pExifData_(0)
    {
    }

    JpegImage::~JpegImage()
    {
        delete[] pExifData_;
    }

    const uint16 JpegImage::soi_    = 0xffd8;
    const uint16 JpegImage::app0_   = 0xffe0;
    const uint16 JpegImage::app1_   = 0xffe1;
    const char JpegImage::exifId_[] = "Exif\0\0";
    const char JpegImage::jfifId_[] = "JFIF\0";

    bool JpegImage::isJpeg(std::istream& is)
    {
        char c;
        is.get(c);
        if (!is.good()) return false;
        if (static_cast<char>((soi_ & 0xff00) >> 8) != c) {
            is.unget();
            return false;
        }
        is.get(c);
        if (!is.good()) return false;
        if (static_cast<char>(soi_ & 0x00ff) != c) {
            is.unget();
            return false;
        }
        return true;
    }

    int JpegImage::readExifData(const std::string& path)
    {
        std::ifstream file(path.c_str(), std::ios::binary);
        if (!file) return -1;
        return readExifData(file);
    }

    // Todo: implement this properly: skip unknown APP0 and APP1 segments
    int JpegImage::readExifData(std::istream& is)
    {
        // Check if this is a JPEG image in the first place
        if (!isJpeg(is)) {
            if (!is.good()) return 1;
            return 2;
        }

        // Read and check section marker and size
        char tmpbuf[10];
        is.read(tmpbuf, 10);
        if (!is.good()) return 1;
        uint16 marker = getUShort(tmpbuf, bigEndian);
        uint16 size = getUShort(tmpbuf + 2, bigEndian);
        if (size < 8) return 3;
        if (!(marker == app1_ && memcmp(tmpbuf + 4, exifId_, 6) == 0)) return 3;

        // Read the rest of the APP1 field (Exif data)
        long sizeExifData = size - 8;
        pExifData_ = new char[sizeExifData];
        is.read(pExifData_, sizeExifData);
        if (!is.good()) {
            delete[] pExifData_;
            pExifData_ = 0;
            return 1;
        }
        // Finally, set the size and offset of the Exif data buffer
        sizeExifData_ = sizeExifData;

        return 0;
    } // JpegImage::readExifData

    int JpegImage::writeExifData(const std::string& path) const
    {
        std::ifstream infile(path.c_str(), std::ios::binary);
        if (!infile) return -1;

        // Write the output to a temporary file
        pid_t pid = getpid();
        std::string tmpname = path + toString(pid);
        std::ofstream outfile(tmpname.c_str(), std::ios::binary);
        if (!outfile) return -2;

        int rc = writeExifData(outfile, infile);
        infile.close();
        outfile.close();
        if (rc == 0) {
            // rename temporary file
            if (rename(tmpname.c_str(), path.c_str()) == -1) rc = -3;
        }
        if (rc != 0) {
            // remove temporary file
            unlink(tmpname.c_str());
        }

        return rc;
    } // JpegImage::writeExifData

    // Todo: implement this properly: skip unknown APP0 and APP1 segments
    int JpegImage::writeExifData(std::ostream& os, std::istream& is) const
    {
        // Check if this is a JPEG image in the first place
        if (!isJpeg(is)) {
            if (!is.good()) return 1;
            return 2;
        }

        // Read and check section marker and size
        char tmpbuf[12];
        is.read(tmpbuf, 10);
        if (!is.good()) return 1;
        uint16 marker = getUShort(tmpbuf, bigEndian);
        uint16 size = getUShort(tmpbuf + 2, bigEndian);
        if (size < 8) return 3;
        if (!(   (marker == app0_ && memcmp(tmpbuf + 4, jfifId_, 5) == 0)
              || (marker == app1_ && memcmp(tmpbuf + 4, exifId_, 6) == 0))) {
            return 3;
        }

        // Write SOI and APP1 markers, size of APP1 field, Exif id and Exif data
        us2Data(tmpbuf, soi_, bigEndian);
        us2Data(tmpbuf + 2, app1_, bigEndian);
        us2Data(tmpbuf + 4, sizeExifData_ + 8, bigEndian);
        memcpy(tmpbuf + 6, exifId_, 6);
        os.write(tmpbuf, 12);
        os.write(pExifData_, sizeExifData_);
        if (!os.good()) return 4;
        // Copy rest of the stream
        is.ignore(size - 8);
        if (!is.good()) return 1;
        os.flush();
        is >> os.rdbuf();
        if (!os.good()) return 4;

        return 0;
    } // JpegImage::writeExifData

    void JpegImage::setExifData(const char* buf, long size)
    {
        sizeExifData_ = size;
        delete[] pExifData_;
        pExifData_ = new char[size];
        memcpy(pExifData_, buf, size);
    }

    TiffHeader::TiffHeader(ByteOrder byteOrder) 
        : byteOrder_(byteOrder), tag_(0x002a), offset_(0x00000008)
    {
    }

    int TiffHeader::read(const char* buf)
    {
        if (buf[0] == 0x49 && buf[1] == 0x49) {
            byteOrder_ = littleEndian;
        }
        else if (buf[0] == 0x4d && buf[1] == 0x4d) {
            byteOrder_ = bigEndian;
        }
        else {
            return 1;
        }
        tag_ = getUShort(buf+2, byteOrder_);
        offset_ = getULong(buf+4, byteOrder_);
        return 0;
    }

    long TiffHeader::copy(char* buf) const
    {
        switch (byteOrder_) {
        case littleEndian:
            buf[0] = 0x49;
            buf[1] = 0x49;
            break;
        case bigEndian:
            buf[0] = 0x4d;
            buf[1] = 0x4d;
            break;
        case invalidByteOrder:
            // do nothing
            break;
        }
        us2Data(buf+2, 0x002a, byteOrder_);
        ul2Data(buf+4, 0x00000008, byteOrder_);
        return size();
    }

}                                       // namespace Exif