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# addmoddel.cpp

Sample usage of high-level metadata operations.

    00001 // ***************************************************************** -*- C++ -*-
    00002 // addmoddel.cpp, $Rev: 631 $
    00003 // Sample program showing how to add, modify and delete Exif metadata.
    00004
    00005 #include "image.hpp"
    00006 #include "exif.hpp"
    00007 #include <iostream>
    00008 #include <iomanip>
    00009 #include <cassert>
    00010
    00011 int main(int argc, char* const argv[])
    00012 try {
    00013     if (argc != 2) {
    00014         std::cout << "Usage: " << argv[0] << " file\n";
    00015         return 1;
    00016     }
    00017     std::string file(argv[1]);
    00018
    00019     // Container for exif metadata. This is an example of creating
    00020     // exif metadata from scratch. If you want to add, modify, delete
    00021     // metadata that exists in an image, start with ImageFactory::open
    00022     Exiv2::ExifData exifData;
    00023
    00024     // *************************************************************************
    00025     // Add to the Exif data
    00026
    00027     // This is the quickest way to add (simple) Exif data. If a metadatum for
    00028     // a given key already exists, its value is overwritten. Otherwise a new
    00029     // tag is added.
    00030     exifData["Exif.Image.Model"] = "Test 1";                     // AsciiValue
    00031     exifData["Exif.Image.SamplesPerPixel"] = uint16_t(162);      // UShortValue
    00032     exifData["Exif.Image.XResolution"] = int32_t(-2);            // LongValue
    00033     exifData["Exif.Image.YResolution"] = Exiv2::Rational(-2, 3); // RationalValue
    00034     std::cout << "Added a few tags the quick way.\n";
    00035
    00036     // Create a ASCII string value (note the use of create)
    00037     Exiv2::Value::AutoPtr v = Exiv2::Value::create(Exiv2::asciiString);
    00038     // Set the value to a string
    00039     v->read("1999:12:31 23:59:59");
    00040     // Add the value together with its key to the Exif data container
    00041     Exiv2::ExifKey key("Exif.Photo.DateTimeOriginal");
    00042     exifData.add(key, v.get());
    00043     std::cout << "Added key \"" << key << "\", value \"" << *v << "\"\n";
    00044
    00045     // Now create a more interesting value (without using the create method)
    00046     Exiv2::URationalValue::AutoPtr rv(new Exiv2::URationalValue);
    00047     // Set two rational components from a string
    00048     rv->read("1/2 1/3");
    00049     // Add more elements through the extended interface of rational value
    00050     rv->value_.push_back(std::make_pair(2,3));
    00051     rv->value_.push_back(std::make_pair(3,4));
    00052     // Add the key and value pair to the Exif data
    00053     key = Exiv2::ExifKey("Exif.Image.PrimaryChromaticities");
    00054     exifData.add(key, rv.get());
    00055     std::cout << "Added key \"" << key << "\", value \"" << *rv << "\"\n";
    00056
    00057     // *************************************************************************
    00058     // Modify Exif data
    00059
    00060     // Since we know that the metadatum exists (or we don't mind creating a new
    00061     // tag if it doesn't), we can simply do this:
    00062     Exiv2::Exifdatum& tag = exifData["Exif.Photo.DateTimeOriginal"];
    00063     std::string date = tag.toString();
    00064     date.replace(0, 4, "2000");
    00065     tag.setValue(date);
    00066     std::cout << "Modified key \"" << key
    00067               << "\", new value \"" << tag.value() << "\"\n";
    00068
    00069     // Alternatively, we can use findKey()
    00070     key = Exiv2::ExifKey("Exif.Image.PrimaryChromaticities");
    00071     Exiv2::ExifData::iterator pos = exifData.findKey(key);
    00072     if (pos == exifData.end()) throw Exiv2::Error(1, "Key not found");
    00073     // Get a pointer to a copy of the value
    00074     v = pos->getValue();
    00075     // Downcast the Value pointer to its actual type
    00076     Exiv2::URationalValue* prv = dynamic_cast<Exiv2::URationalValue*>(v.release());
    00077     if (prv == 0) throw Exiv2::Error(1, "Downcast failed");
    00078     rv = Exiv2::URationalValue::AutoPtr(prv);
    00079     // Modify the value directly through the interface of URationalValue
    00080     rv->value_[2] = std::make_pair(88,77);
    00081     // Copy the modified value back to the metadatum
    00082     pos->setValue(rv.get());
    00083     std::cout << "Modified key \"" << key
    00084               << "\", new value \"" << pos->value() << "\"\n";
    00085
    00086     // *************************************************************************
    00087     // Delete metadata from the Exif data container
    00088
    00089     // Delete the metadatum at iterator position pos
    00090     key = Exiv2::ExifKey("Exif.Image.PrimaryChromaticities");
    00091     pos = exifData.findKey(key);
    00092     if (pos == exifData.end()) throw Exiv2::Error(1, "Key not found");
    00093     exifData.erase(pos);
    00094     std::cout << "Deleted key \"" << key << "\"\n";
    00095
    00096     // *************************************************************************
    00097     // Finally, write the remaining Exif data to the image file
    00098     Exiv2::Image::AutoPtr image = Exiv2::ImageFactory::open(file);
    00099     assert(image.get() != 0);
    00100
    00101     image->setExifData(exifData);
    00102     image->writeMetadata();
    00103
    00104     return 0;
    00105 }
    00106 catch (Exiv2::AnyError& e) {
    00107     std::cout << "Caught Exiv2 exception '" << e << "'\n";
    00108     return -1;
    00109 }