__doctype__
<html>
__header2__
<body>

<div id="content">
__index1__

<h1>Getting started</h1>

<h2><a href="namespaces.html">Namespaces</a></h2>

<p>The <a href="index.html">Exiv2 library</a> is made up of all
elements defined in the <a href="namespaceExiv2.html">Exiv2
namespace</a>. The Action and Util namespaces are only used by the
Exiv2 command line utility. Thus, to learn about the library, focus on
the members of the Exiv2 namespace.</p>

<h2><a href="classes.html">Classes</a></h2>

<p>The top-level class of the Exiv2 library is 
<a class="el" href="classExiv2_1_1Image.html">Exiv2::Image</a>
 
(don't let the components diagram below mislead you). Exiv2::Image
defines the interface to access various image metadata. Derived from
Exiv2::Image are the implementations of different image formats. Most
applications will use
<a class="el" href="classExiv2_1_1ImageFactory.html">Exiv2::ImageFactory</a> 
to access images in files or memory, in which case the image format 
is transparent to them.</p>

<p>Metadata is manipulated through the classes
<a class="el" href="classExiv2_1_1ExifData.html">Exiv2::ExifData</a> 
and <a class="el" href="classExiv2_1_1IptcData.html">Exiv2::IptcData</a>
of the Exiv2 library. They hold a container
of Exif and IPTC metadata, respectively, and define related methods to
access and manipulate the metadata. The containers hold objects derived from
<a class="el" href="classExiv2_1_1Metadatum.html">Exiv2::Metadatum</a>. 
Interface class Exiv2::Metadatum defines methods to access the
information of one Exif tag or IPTC dataset. It models the tag data as
a key and value pair. 
The abstract base class 
<a class="el" href="classExiv2_1_1Key.html">Exiv2::Key</a> defines the 
interface for a key. Concrete keys implement Exif and IPTC keys.
The abstract base class 
<a class="el" href="classExiv2_1_1Value.html">Exiv2::Value</a> defines 
the interface to access tag information, from which concrete values are
derived. The actual value used in a metadatum depends on the type of
the Exif tag or IPTC dataset. It is usually determined when the Exif metadata 
is read from an image. It is also possible to manually create a Value and
together with a key add it to an ExifData or IptcData container.</p>

<h2><a href="examples.html">Examples</a></h2>

<p>There are several simple examples that demonstrate the basic use of Exiv2
functionality: <a href="exifprint_8cpp-example.html">Exifprint</a> 
shows how the Exif data of an image can be read and written to the screen.
<a href="iptcprint_8cpp-example.html">Iptcprint</a> is a similar 
example to print IPTC data.
<a href="addmoddel_8cpp-example.html">Addmoddel</a> shows how to
add, modify and delete Exif metadata. 
<a href="exifcomment_8cpp-example.html">Exifcomment</a> shows how to
set the exif comment of an image. 
For more real-world code have a look at the implementation of the
different actions of the Exiv2 utility (actions.cpp).</p>

<h2><a href="makernote.html">Makernotes</a></h2>

<p>Exif Makernote data can be accessed through ExifData in the same
way as the standard Exif tags. In other words, for each entry of a
known Makernote, there is a corresponding Metadatum in the ExifData
container. The abstract base class 
<a class="el" href="classExiv2_1_1MakerNote.html">Exiv2::MakerNote</a> defines
the Makernote interface. Subclass 
<a class="el" href="classExiv2_1_1IfdMakerNote.html">Exiv2::IfdMakerNote</a>
models makernotes encoded in IFD format. 
<a href="classExiv2_1_1MakerNote.html#_details">Implementing a new
IFD makernote</a> is straightforward. Implementing a new makernote that is not
encoded in IFD format however, is more difficult. Please 
<a href="mailto:ahuggel@gmx.net"> contact me</a> if you have such a
makernote specification and would like assistance adding it to Exiv2.</p>
  
<h2><a class="anchor">IFD (Image File Directory)</a></h2>

<p><a class="el" href="classExiv2_1_1Ifd.html">Exiv2::Ifd</a> is a generic
low-level class that models an image file directory as defined by TIFF
and used in the Exif standard.  Exiv2::Ifd could be used to implement
read only as well as read/write access to Exif (or TIFF) data without
the overhead (and convenience) of Exiv2::ExifData.</p>

<h2><a class="anchor">Components</a></h2>

<p>The picture below shows the components that make up the Exiv2
library and how they depend on each other. Component names are the
same as the basenames of their source files. Each component has its
own header and source files.</p>

<center>
<h3><a class="anchor">Exiv2 Components Diagram</a></h3>
<p><img src="../include/exiv2-components.png" width="660" height="543" alt="Exiv2 components diagram"></p>
</center>
<p>&nbsp;</p>

</div>
<!-- closes content -->

</body>
</html>
