addmoddel.cpp

Sample usage of high-level metadata operations.

// ***************************************************************** -*- C++ -*-
// addmoddel.cpp, $Rev$
// 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"] = int32_t(-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
rv->value_.push_back(std::make_pair(2,3));
rv->value_.push_back(std::make_pair(3,4));
// 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");
tag.setValue(date);
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(1, "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(1, "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
pos->setValue(rv.get());
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(1, "Key not found");
exifData.erase(pos);
std::cout << "Deleted key \"" << key << "\"\n";
// *************************************************************************
// Finally, write the remaining Exif data to the image file
assert(image.get() != 0);
image->setExifData(exifData);
image->writeMetadata();
return 0;
}
catch (Exiv2::AnyError& e) {
std::cout << "Caught Exiv2 exception '" << e << "'\n";
return -1;
}