osg 文件路径解析

最近项目开发遇到文件路径解析的问题，比如获取名字、获取文件父路径、获取相对路径、斜杠转化等等。在查看osgdb源码是突然发现osg已经写好了很多函数，供我们调用，可以提高项目开发的速度：

/** Gets the parent path from full name (Ex: /a/b/c.Ext => /a/b). */
extern OSGDB_EXPORT std::string getFilePath(const std::string& filename);
/** Gets the extension without dot (Ex: /a/b/c.Ext => Ext). */
extern OSGDB_EXPORT std::string getFileExtension(const std::string& filename);
/** Gets the extension including dot (Ex: /a/b/c.Ext => .Ext). */
extern OSGDB_EXPORT std::string getFileExtensionIncludingDot(const std::string& filename);
/** Gets the lowercase extension without dot (Ex: /a/b/c.Ext => ext). */
extern OSGDB_EXPORT std::string getLowerCaseFileExtension(const std::string& filename);
/** Gets file name with extension (Ex: /a/b/c.Ext => c.Ext). */
extern OSGDB_EXPORT std::string getSimpleFileName(const std::string& fileName);
/** Gets file path without last extension (Ex: /a/b/c.Ext => /a/b/c ; file.ext1.ext2 => file.ext1). */
extern OSGDB_EXPORT std::string getNameLessExtension(const std::string& fileName);
/** Gets file path without \b all extensions (Ex: /a/b/c.Ext => /a/b/c ; file.ext1.ext2 => file). */
extern OSGDB_EXPORT std::string getNameLessAllExtensions(const std::string& fileName);
/** Gets file name without last extension (Ex: /a/b/c.Ext => c ; file.ext1.ext2 => file.ext1). */
extern OSGDB_EXPORT std::string getStrippedName(const std::string& fileName);
/** If 'to' is in a subdirectory of 'from' then this function returns the subpath, otherwise it just returns the file name.
  * The function does \b not automagically resolve paths as the system does, so be careful to give canonical paths.
  * However, the function interprets slashes ('/') ans backslashes ('\') as they were equal.
  */
extern OSGDB_EXPORT std::string getPathRelative(const std::string& from, const std::string& to);
/** Gets root part of a path ("/" or "C:"), or an empty string if none found. */
extern OSGDB_EXPORT std::string getPathRoot(const std::string& path);
/** Tests if path is absolute, as !getPathRoot(path).empty(). */
extern OSGDB_EXPORT bool isAbsolutePath(const std::string& path);


/** Converts forward slashes (/) to back slashes (\). */
extern OSGDB_EXPORT std::string convertFileNameToWindowsStyle(const std::string& fileName);
/** Converts back slashes (\) to forward slashes (/). */
extern OSGDB_EXPORT std::string convertFileNameToUnixStyle(const std::string& fileName);
extern OSGDB_EXPORT std::string convertToLowerCase(const std::string& fileName);

const char UNIX_PATH_SEPARATOR = '/';
const char WINDOWS_PATH_SEPARATOR = '\\';

/** Get the path separator for the current platform. */
extern OSGDB_EXPORT char getNativePathSeparator();
/** Check if the path contains only the current platform's path separators. */
extern OSGDB_EXPORT bool isFileNameNativeStyle(const std::string& fileName);
/** Convert the path to contain only the current platform's path separators. */
extern OSGDB_EXPORT std::string convertFileNameToNativeStyle(const std::string& fileName);

extern OSGDB_EXPORT bool equalCaseInsensitive(const std::string& lhs,const std::string& rhs);
extern OSGDB_EXPORT bool equalCaseInsensitive(const std::string& lhs,const char* rhs);

extern OSGDB_EXPORT bool containsServerAddress(const std::string& filename);
extern OSGDB_EXPORT std::string getServerProtocol(const std::string& filename);
extern OSGDB_EXPORT std::string getServerAddress(const std::string& filename);
extern OSGDB_EXPORT std::string getServerFileName(const std::string& filename);

/** Concatenates two paths */
extern OSGDB_EXPORT std::string concatPaths(const std::string& left, const std::string& right);

/** Removes .. and . dirs in a path */
extern OSGDB_EXPORT std::string getRealPath(const std::string& path);

/** Splits a path into elements between separators (including Windows' root, if any). */
extern OSGDB_EXPORT void getPathElements(const std::string& path, std::vector<std::string> & out_elements);

比如我获取相对路径的代码：

        //对话框获取的路径
std::string localurl = _localUrlEdit->text().toStdString();
        
//工程文件所在路径        
std::string prjPath = _mapNode->getSceneDocument()->getPathName();


        std::string ext = osgDB::getFilePath( prjPath );
        std::string sublocalurl;
        if (ext.length()< localurl.length())
        {
            sublocalurl = localurl.substr(ext.length()+1);
            sublocalurl = osgDB::convertFileNameToWindowsStyle(sublocalurl);
        }