Sample usage of high-level metadata operations.

// ***************************************************************** -*- C++ -*-
// addmoddel.cpp
// Sample program showing how to add, modify and delete Exif metadata.
#include <exiv2/exiv2.hpp>
#include <iostream>
#include <iomanip>
#include <cassert>
int main(int argc, char* const argv[])
try {
if (argc != 2) {
std::cout << "Usage: " << argv[0] << " file\n";
return 1;
std::string file(argv[1]);
// Container for exif metadata. This is an example of creating
// exif metadata from scratch. If you want to add, modify, delete
// metadata that exists in an image, start with ImageFactory::open
Exiv2::ExifData exifData;
// *************************************************************************
// Add to the Exif data
// This is the quickest way to add (simple) Exif data. If a metadatum for
// a given key already exists, its value is overwritten. Otherwise a new
// tag is added.
exifData["Exif.Image.Model"] = "Test 1"; // AsciiValue
exifData["Exif.Image.SamplesPerPixel"] = uint16_t(162); // UShortValue
exifData["Exif.Image.XResolution"] = -2; // LongValue
exifData["Exif.Image.YResolution"] = Exiv2::Rational(-2, 3); // RationalValue
std::cout << "Added a few tags the quick way.\n";
// Create a ASCII string value (note the use of create)
// Set the value to a string
v->read("1999:12:31 23:59:59");
// Add the value together with its key to the Exif data container
Exiv2::ExifKey key("Exif.Photo.DateTimeOriginal");
exifData.add(key, v.get());
std::cout << "Added key \"" << key << "\", value \"" << *v << "\"\n";
// Now create a more interesting value (without using the create method)
// Set two rational components from a string
rv->read("1/2 1/3");
// Add more elements through the extended interface of rational value
// Add the key and value pair to the Exif data
key = Exiv2::ExifKey("Exif.Image.PrimaryChromaticities");
exifData.add(key, rv.get());
std::cout << "Added key \"" << key << "\", value \"" << *rv << "\"\n";
// *************************************************************************
// Modify Exif data
// Since we know that the metadatum exists (or we don't mind creating a new
// tag if it doesn't), we can simply do this:
Exiv2::Exifdatum& tag = exifData["Exif.Photo.DateTimeOriginal"];
date.replace(0, 4, "2000");
std::cout << "Modified key \"" << tag.key()
<< "\", new value \"" << tag.value() << "\"\n";
// Alternatively, we can use findKey()
key = Exiv2::ExifKey("Exif.Image.PrimaryChromaticities");
Exiv2::ExifData::iterator pos = exifData.findKey(key);
if (pos == exifData.end()) throw Exiv2::Error(Exiv2::kerErrorMessage, "Key not found");
// Get a pointer to a copy of the value
v = pos->getValue();
// Downcast the Value pointer to its actual type
Exiv2::URationalValue* prv = dynamic_cast<Exiv2::URationalValue*>(v.release());
if (prv == 0) throw Exiv2::Error(Exiv2::kerErrorMessage, "Downcast failed");
// Modify the value directly through the interface of URationalValue
rv->value_[2] = std::make_pair(88,77);
// Copy the modified value back to the metadatum
std::cout << "Modified key \"" << key
<< "\", new value \"" << pos->value() << "\"\n";
// *************************************************************************
// Delete metadata from the Exif data container
// Delete the metadatum at iterator position pos
key = Exiv2::ExifKey("Exif.Image.PrimaryChromaticities");
pos = exifData.findKey(key);
if (pos == exifData.end()) throw Exiv2::Error(Exiv2::kerErrorMessage, "Key not found");
std::cout << "Deleted key \"" << key << "\"\n";
// *************************************************************************
// Finally, write the remaining Exif data to the image file
assert(image.get() != 0);
return 0;
catch (Exiv2::AnyError& e) {
std::cout << "Caught Exiv2 exception '" << e << "'\n";
return -1;
const Value & value() const
Return a constant reference to the value.
std::string toString() const
Return the value as a string.
void add(const ExifKey &key, const Value *pValue)
Add an Exifdatum from the supplied key and value pair. This method copies (clones) key and value....
An Exif metadatum, consisting of an ExifKey and a Value and methods to manipulate these.
Definition: exif.hpp:59
Include all Exiv2 header files.
@ asciiString
Exif ASCII type, 8-bit byte.
Definition: types.hpp:132
Error class interface. Allows the definition and use of a hierarchy of error classes which can all be...
Definition: error.hpp:174
iterator end()
End of the metadata.
Definition: exif.hpp:492
static AutoPtr create(TypeId typeId)
A (simple) factory to create a Value type.
Concrete keys for Exif metadata and access to Exif tag reference data.
Definition: tags.hpp:148
std::pair< int32_t, int32_t > Rational
8 byte signed rational type.
Definition: types.hpp:110
iterator erase(iterator pos)
Delete the Exifdatum at iterator position pos, return the position of the next exifdatum....
std::string key() const
Return the key of the Exifdatum.
@ date
IPTC date type.
Definition: types.hpp:148
std::auto_ptr< Image > AutoPtr
Image auto_ptr type.
Definition: image.hpp:84
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...
BasicError< char > Error
Error class used for exceptions (std::string based)
Definition: error.hpp:323
std::auto_ptr< ValueType< T > > AutoPtr
Shortcut for a ValueType<T> auto pointer.
Definition: value.hpp:1247
@ string
IPTC string type.
Definition: types.hpp:147
iterator findKey(const ExifKey &key)
Find the first Exifdatum with the given key, return an iterator to it.
ExifMetadata::iterator iterator
ExifMetadata iterator type.
Definition: exif.hpp:437
Template for a Value of a basic type. This is used for unsigned and signed short, long and rationals.
Definition: value.hpp:1244
std::auto_ptr< Value > AutoPtr
Shortcut for a Value auto pointer.
Definition: value.hpp:63
A container for Exif data. This is a top-level class of the Exiv2 library. The container holds Exifda...
Definition: exif.hpp:434