ExternalFileWriter

/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield 
 *
 * This library is open source and may be redistributed and/or modified under  
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 * OpenSceneGraph Public License for more details.
*/

#ifndef OSGDB_PLUGIN_IMAGE_WRITER
#define OSGDB_PLUGIN_IMAGE_WRITER 1

#include <osgDB/Export>
#include <string>
#include <map>

namespace osg
{
    class Object;
}

namespace osgDB
{

    class Options;

    /// Helper allowing 'intelligent' writing of external files (images, shaders, etc.), regarding to a main file (a scene), especially in plugins.
    /// Goals are:
    ///   - Enable writing out objects only once (even if referenced multiple times)
    ///   - Handle duplicates (avoid writing two different objects at the same place, renaming files as needed)
    ///   - Handle directory creation when paths don't just exist
    ///   - Generate writing paths which may keep original directory structure (depending on user wishes). Ex:
    ///       Reading: model.osg and images/img1.jpg
    ///          Writing with    'keepRelativePaths': /somePath/newmodel.osg and /somePath/images/img1.jpg
    ///          Writing without 'keepRelativePaths': /somePath/newmodel.osg and /somePath/img1.jpg
    ///\author Sukender
    ///\todo Handling of naming constraints (such as "8.3" names in 3DS)
    class OSGDB_EXPORT ExternalFileWriter
    {
    public:
        /// Builds the helper class with all options.
        ///\param srcDirectory Directory of the initial main file (if any), used as a base when relativising objects names. Not used if keepRelativePaths==false.
        ///\param destDirectory Directory where to write the main file.
        ///\param keepRelativePaths If true, then relative paths of source objects are kept if possible (ex: If an image is initially "imageDir/image.jpg" relatively to the source dir, then we'd like to get "destDir/imageDir/image.jpg"). If false, then only the simple file name is used to write the object file.
        ///\param allowUpDirs When relativising objects paths, sets the maximum number of directories the objects can be written "up" the destination directory. Not used if keepRelativePaths==false. Examples: If an image is initially "../image.jpg" relatively to the source dir *AND* if we allow one dir level up, then we'd like to get "destDirParent/destDir/../image.jpg" (= "destDirParent/image.jpg"). If we *DO NOT* allow one dir level up, then we'd like to get "destDir/image.jpg".
        ExternalFileWriter(const std::string & srcDirectory, const std::string & destDirectory, bool keepRelativePaths, unsigned int allowUpDirs=0);

        /// Short constructor used when not relativising objects paths, or when having no initial model file (which is pretty the same here).
        ExternalFileWriter(const std::string & destDirectory);

        /// Writes the current object if not already done.
        ///\param obj Object to write, using corresponding osgDB::write method.
        ///\param options Writing options to pass to corresponding osgDB::write method.
        ///\param [out] out_absolutePath Pointer to a string to be filled with absolute writing path, or NULL.
        ///\param [out] out_relativePath Pointer to a string to be filled with write path relative to the destination directory if possible (absolute path if not), or NULL.
        ///\return true on success, false otherwise.
        bool write(const osg::Object & obj, const osgDB::Options * options, std::string * out_absolutePath=NULL, std::string * out_relativePath=NULL);

        struct ObjectData
        {
            ObjectData() : written(false) {}
            ObjectData(const std::string & absolutePath, const std::string & relativePath, bool written) : absolutePath(absolutePath), relativePath(relativePath), written(written) {}
            std::string absolutePath;
            std::string relativePath;
            bool written;        ///< Says if write succeded or not.
        };

        /// Set of written objects, with their absolute writing path.
        /// Objects being passed to the write() method but which have failed to be effectively written are also included.
        typedef std::map<const osg::Object*, ObjectData> ObjectsSet;

        /// Returns the written objects.
        const ObjectsSet & getObjects() const { return _objects; }

    protected:
        // Dev note:
        // A multi-indexed structure would be more efficient for ObjectsSet (such as boost::multi_index, indexed on object pointer (unique), and hashed indexed on absolute path (unique)).
        // In order to get a correct search time, SearchMap "replaces" the multi-index structure for hashed indexes on absolute paths.
        typedef std::multimap<unsigned int, const osg::Object*> SearchMap;
        typedef unsigned int ObjectIndex;       ///< Integer type used for indices of unnamed objects
        ObjectsSet _objects;
        SearchMap _searchMap;                    ///< Map used to search by absolute file path.
        ObjectIndex _lastGeneratedObjectIndex;
        const std::string _srcDirectory;
        const std::string _destDirectory;
        bool _keepRelativePaths;
        const unsigned int _allowUpDirs;

        /// Generates a unique name for an object to be written on disk.
        /// Side effect: updates _lastGeneratedObjectIndex to the index associated withe the returned name.
        void generateObjectName(std::string & out_relativePath, std::string & out_absolutePath, int type);

        bool absoluteObjectPathExists(const std::string & path);

    private:
        // Prevent copy
        ExternalFileWriter & operator=(const ExternalFileWriter &);
        ExternalFileWriter(const ExternalFileWriter &);
    };
}

#endif    // OSGDB_PLUGIN_IMAGE_WRITER