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__header2__
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<body>
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<div id="content">
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__index1__
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<h1>Getting started</h1>
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<h2><a href="namespaces.html">Namespaces</a></h2>
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<p>The <a href="index.html">Exiv2 library</a> is made up of all
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elements defined in the <a href="namespaceExiv2.html">Exiv2
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namespace</a>. The Action and Util namespaces are only used by the
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Exiv2 command line utility. Thus, to learn about the library, focus on
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the members of the Exiv2 namespace.</p>
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<h2><a href="classes.html">Classes</a></h2>
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<p>The top-level class of the Exiv2 library is
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<a class="el" href="classExiv2_1_1Image.html">Exiv2::Image</a>
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(don't let the components diagram below mislead you). Exiv2::Image
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defines the interface to access various image metadata. Derived from
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Exiv2::Image are the implementations of different image formats.
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However, the only image format currently supported is Jpeg. Most
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applications will use
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<a class="el" href="classExiv2_1_1ImageFactory.html">Exiv2::ImageFactory</a>
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to access images in files or memory, in which case the image format
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is transparent to them.</p>
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<p>Metadata is manipulated through the classes
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<a class="el" href="classExiv2_1_1ExifData.html">Exiv2::ExifData</a>
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and <a class="el" href="classExiv2_1_1IptcData.html">Exiv2::IptcData</a>
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of the Exiv2 library. They hold a container
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of Exif and Iptc metadata, respectively, and define related methods to
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access and manipulate the metadata. The containers hold objects derived from
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<a class="el" href="classExiv2_1_1Metadatum.html">Exiv2::Metadatum</a>.
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Interface class Exiv2::Metadatum defines methods to access the
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information of one Exif tag or Iptc dataset. It models the tag data as
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a key and value pair.
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The abstract base class
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<a class="el" href="classExiv2_1_1Key.html">Exiv2::Key</a> defines the
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interface for a key. Concrete keys implement Exif and Iptc keys.
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The abstract base class
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<a class="el" href="classExiv2_1_1Value.html">Exiv2::Value</a> defines
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the interface to access tag information, from which concrete values are
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derived. The actual value used in a metadatum depends on the type of
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the Exif tag or Iptc dataset. It is usually determined when the Exif metadata
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is read from an image. It is also possible to manually create a Value and
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together with a key add it to an ExifData or IptcData container.</p>
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<h2><a href="examples.html">Examples</a></h2>
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<p>There are several simple examples that demonstrate the basic use of Exiv2
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functionality: <a href="exifprint_8cpp-example.html">Exifprint</a>
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shows how the Exif data of an image can be read and written to the screen.
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<a href="iptcprint_8cpp-example.html">Iptcprint</a> is a similar
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example to print Iptc data.
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<a href="addmoddel_8cpp-example.html">Addmoddel</a> shows how to
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add, modify and delete Exif metadata.
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<a href="exifcomment_8cpp-example.html">Exifcomment</a> shows how to
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set the exif comment of an image.
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For more real-world code have a look at the implementation of the
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different actions of the Exiv2 utility (actions.cpp).</p>
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<h2><a href="makernote.html">Makernotes</a></h2>
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<p>Exif Makernote data can be accessed through ExifData in the same
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way as the standard Exif tags. In other words, for each entry of a
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known Makernote, there is a corresponding Metadatum in the ExifData
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container. The abstract base class
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<a class="el" href="classExiv2_1_1MakerNote.html">Exiv2::MakerNote</a> defines
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the Makernote interface. Subclass
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<a class="el" href="classExiv2_1_1IfdMakerNote.html">Exiv2::IfdMakerNote</a>
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models makernotes encoded in IFD format.
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<a href="classExiv2_1_1MakerNote.html#_details">Implementing a new
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IFD makernote</a> is straightforward. Implementing a new makernote that is not
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encoded in IFD format however, is more difficult. Please
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<a href="mailto:ahuggel@gmx.net"> contact me</a> if you have such a
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makernote specification and would like assistance adding it to Exiv2.</p>
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<h2><a class="anchor">IFD (Image File Directory)</a></h2>
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<p><a class="el" href="classExiv2_1_1Ifd.html">Exiv2::Ifd</a> is a generic
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low-level class that models an image file directory as defined by TIFF
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and used in the Exif standard. Exiv2::Ifd could be used to implement
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read only as well as read/write access to Exif (or TIFF) data without
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the overhead (and convenience) of Exiv2::ExifData.</p>
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<h2><a class="anchor">Components</a></h2>
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<p>The picture below shows the components that make up the Exiv2
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library and how they depend on each other. Component names are the
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same as the basenames of their source files. Each component has its
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own header and source files.</p>
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<center>
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<h3><a class="anchor">Exiv2 Components Diagram</a></h3>
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<p><img src="../include/exiv2-components.png" width="660" height="543" alt="Exiv2 components diagram"></p>
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</center>
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<p> </p>
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</div>
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