Exiv2
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;
}
}
Exiv2::DataBuf::pData_
byte * pData_
Pointer to the buffer, 0 if none has been allocated.
Definition: types.hpp:269
Exiv2::FileIo
Provides binary file IO by implementing the BasicIo interface.
Definition: basicio.hpp:296
exif.hpp
Encoding and decoding of Exif data.
Exiv2::ExifData::findKey
iterator findKey(const ExifKey &key)
Find the first Exifdatum with the given key, return an iterator to it.
Definition: exif.cpp:581
Exiv2::ExifData::const_iterator
ExifMetadata::const_iterator const_iterator
ExifMetadata const iterator type.
Definition: exif.hpp:439
Exiv2::AnyError
Error class interface. Allows the definition and use of a hierarchy of error classes which can all be...
Definition: error.hpp:174
Exiv2::ExifData::end
iterator end()
End of the metadata.
Definition: exif.hpp:492
Exiv2::ImageFactory::open
static Image::AutoPtr open(const std::string &path, bool useCurl=true)
Create an Image subclass of the appropriate type by reading the specified file. Image type is derived...
Definition: image.cpp:893
Exiv2::DataBuf
Utility class containing a character array. All it does is to take care of memory allocation and dele...
Definition: types.hpp:204
Exiv2::ExifKey
Concrete keys for Exif metadata and access to Exif tag reference data.
Definition: tags.hpp:148
Exiv2::DataBuf::size_
long size_
The current size of the buffer.
Definition: types.hpp:271
image.hpp
Exiv2::ExifData::empty
bool empty() const
Return true if there is no Exif metadata.
Definition: exif.hpp:512
Exiv2::Image::AutoPtr
std::auto_ptr< Image > AutoPtr
Image auto_ptr type.
Definition: image.hpp:84
Exiv2::Error
BasicError< char > Error
Error class used for exceptions (std::string based)
Definition: error.hpp:323
Exiv2::string
IPTC string type.
Definition: types.hpp:147
Exiv2::FileIo::close
virtual int close()
Flush and unwritten data and close the file . It is safe to call close on an already closed instance.
Definition: basicio.cpp:981
Exiv2::FileIo::open
int open(const std::string &mode)
Open the file using using the specified mode.
Definition: basicio.cpp:958
Exiv2::FileIo::write
virtual long write(const byte *data, long wcount)
Write data to the file. The file position is advanced by the number of bytes written.
Definition: basicio.cpp:579
error.hpp
Error class for exceptions, log message class.
Exiv2::ExifData
A container for Exif data. This is a top-level class of the Exiv2 library. The container holds Exifda...
Definition: exif.hpp:434