mrwthumb.cpp

Sample program to extract a Minolta thumbnail from the makernote

// ***************************************************************** -*- C++ -*-
// mrwthumb.cpp
// Sample program to extract a Minolta thumbnail from the makernote
#include "error.hpp"
#include "exif.hpp"
#include "image.hpp"
#include <cassert>
#include <iostream>
int main(int argc, char* const argv[])
{
try {
if (argc != 2) {
std::cout << "Usage: " << argv[0] << " file\n";
return 1;
}
assert(image.get() != 0);
image->readMetadata();
Exiv2::ExifData& exifData = image->exifData();
if (exifData.empty()) {
std::string error(argv[1]);
error += ": No Exif data found in the file";
throw Exiv2::Error(Exiv2::kerErrorMessage, error);
}
Exiv2::ExifKey key("Exif.Minolta.ThumbnailOffset");
Exiv2::ExifData::const_iterator format = exifData.findKey(key);
if (format != exifData.end()) {
Exiv2::DataBuf buf = format->dataArea();
// The first byte of the buffer needs to be patched
buf.pData_[0] = 0xff;
Exiv2::FileIo file("img_thumb.jpg");
file.open("wb");
file.write(buf.pData_, buf.size_);
file.close();
}
return 0;
} catch (Exiv2::AnyError& e) {
std::cout << "Caught Exiv2 exception '" << e << "'\n";
return -1;
}
}