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// ***************************************************************** -*- C++ -*-
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* Copyright (C) 2004, 2005 Andreas Huggel <ahuggel@gmx.net>
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* This program is part of the Exiv2 distribution.
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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@brief Provides abstract base classes Metadatum and Key
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@author Andreas Huggel (ahu)
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<a href="mailto:ahuggel@gmx.net">ahuggel@gmx.net</a>
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@author Brad Schick (brad)
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<a href="mailto:brad@robotbattle.com">brad@robotbattle.com</a>
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@date 09-Jan-04, ahu: created<BR>
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31-Jul-04, brad: isolated as a component<BR>
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23-Aug-04, ahu: added Key
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#ifndef METADATUM_HPP_
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#define METADATUM_HPP_
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// *****************************************************************************
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// included header files
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// + standard includes
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// *****************************************************************************
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// namespace extensions
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// *****************************************************************************
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@brief Abstract base class defining the %Key of a metadatum.
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Keys are used to identify and group metadata.
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//! Shortcut for a %Key auto pointer.
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typedef std::auto_ptr<Key> AutoPtr;
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@brief Return the key of the metadatum as a string. The key is of the
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form 'familyName.groupName.tagName'. Note however that the
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key is not necessarily unique, e.g., an ExifData may contain
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multiple metadata with the same key.
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virtual std::string key() const =0;
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//! Return an identifier for the type of metadata (the first part of the key)
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virtual const char* familyName() const =0;
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//! Return the name of the group (the second part of the key)
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virtual std::string groupName() const =0;
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//! Return the name of the tag (which is also the third part of the key)
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virtual std::string tagName() const =0;
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//! Return the tag number
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virtual uint16_t tag() const =0;
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@brief Return an auto-pointer to a copy of itself (deep copy).
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The caller owns this copy and the auto-pointer ensures that it
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AutoPtr clone() const;
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@brief Write the key to an output stream. You do not usually have
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to use this function; it is used for the implementation of
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the output operator for %Key,
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operator<<(std::ostream &os, const Key &key).
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std::ostream& write(std::ostream& os) const { return os << key(); }
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//! @name Manipulators
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@brief Assignment operator. Protected so that it can only be used
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by subclasses but not directly.
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Key& operator=(const Key& rhs) { return *this; }
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//! Internal virtual copy constructor.
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virtual Key* clone_() const =0;
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//! Output operator for Key types
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inline std::ostream& operator<<(std::ostream& os, const Key& key)
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return key.write(os);
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@brief Abstract base class defining the interface to access information
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related to one metadata tag.
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//! Default Constructor
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Metadatum(const Metadatum& rhs) {}
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virtual ~Metadatum() {}
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//! @name Manipulators
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@brief Set the value. This method copies (clones) the value pointed
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virtual void setValue(const Value* pValue) =0;
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@brief Set the value to the string buf.
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Uses Value::read(const std::string& buf). If the metadatum does
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not have a value yet, then an AsciiValue is created.
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virtual void setValue(const std::string& buf) =0;
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@brief Write value to a data buffer and return the number
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The user must ensure that the buffer has enough memory. Otherwise
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the call results in undefined behaviour.
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@param buf Data buffer to write to.
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@param byteOrder Applicable byte order (little or big endian).
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@return Number of characters written.
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virtual long copy(byte* buf, ByteOrder byteOrder) const =0;
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@brief Return the key of the metadatum. The key is of the form
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'familyName.ifdItem.tagName'. Note however that the key
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is not necessarily unique, i.e., an ExifData may contain
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multiple metadata with the same key.
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virtual std::string key() const =0;
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//! Return the name of the tag (which is also the third part of the key)
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virtual std::string tagName() const =0;
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virtual uint16_t tag() const =0;
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//! Return the type id of the value
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virtual TypeId typeId() const =0;
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//! Return the name of the type
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virtual const char* typeName() const =0;
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//! Return the size in bytes of one component of this type
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virtual long typeSize() const =0;
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//! Return the number of components in the value
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virtual long count() const =0;
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//! Return the size of the value in bytes
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virtual long size() const =0;
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//! Return the value as a string.
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virtual std::string toString() const =0;
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@brief Return the n-th component of the value converted to long. The
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return value is -1 if the value of the Metadatum is not set and
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the behaviour of the method is undefined if there is no n-th
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virtual long toLong(long n =0) const =0;
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@brief Return the n-th component of the value converted to float. The
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return value is -1 if the value of the Metadatum is not set and
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the behaviour of the method is undefined if there is no n-th
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virtual float toFloat(long n =0) const =0;
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@brief Return the n-th component of the value converted to
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Rational. The return value is -1/1 if the value of the
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Metadatum is not set and the behaviour of the method is
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undefined if there is no n-th component.
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virtual Rational toRational(long n =0) const =0;
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@brief Return an auto-pointer to a copy (clone) of the value. The
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caller owns this copy and the auto-poiner ensures that it will
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This method is provided for users who need full control over the
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value. A caller may, e.g., downcast the pointer to the appropriate
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subclass of Value to make use of the interface of the subclass to set
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or modify its contents.
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@return An auto-pointer containing a pointer to a copy (clone) of the
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value, 0 if the value is not set.
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virtual Value::AutoPtr getValue() const =0;
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@brief Return a constant reference to the value.
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This method is provided mostly for convenient and versatile output of
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the value which can (to some extent) be formatted through standard
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stream manipulators. Do not attempt to write to the value through
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ExifData::const_iterator i = exifData.findKey(key);
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if (i != exifData.end()) {
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std::cout << i->key() << " " << std::hex << i->value() << "\n";
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@return A constant reference to the value.
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@throw Error if the value is not set.
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virtual const Value& value() const =0;
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//! @name Manipulators
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@brief Assignment operator. Protected so that it can only be used
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by subclasses but not directly.
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Metadatum& operator=(const Metadatum& rhs) { return *this; }
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}; // class Metadatum
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//! Unary predicate that matches a Exifdatum with a given key
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class FindMetadatumByKey {
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//! Constructor, initializes the object with the tag to look for
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FindMetadatumByKey(const std::string& key) : key_(key) {}
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@brief Returns true if the key of the argument metadatum is equal
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to that of the object.
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bool operator()(const Metadatum& metadatum) const
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{ return key_ == metadatum.key(); }
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}; // class FindMetadatumByTag
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@brief Output operator for Metadatum types, printing the interpreted
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std::ostream& operator<<(std::ostream& os, const Metadatum& md);
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@brief Compare two metadata by tag. Return true if the tag of metadatum
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lhs is less than that of rhs.
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bool cmpMetadataByTag(const Metadatum& lhs, const Metadatum& rhs);
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@brief Compare two metadata by key. Return true if the key of metadatum
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lhs is less than that of rhs.
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bool cmpMetadataByKey(const Metadatum& lhs, const Metadatum& rhs);
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#endif // #ifndef METADATUM_HPP_
added
removed
src/plugins/exiv2/metadatum.hpp
