Qt技巧：获取本地系统标准路径

Qt提供QStandardPaths:standardLocations(type)方法来获取系统的标准路径(列表)，其中type 的取值如下：

Constant	Value	Description
QStandardPaths::DesktopLocation	0	Returns the user's desktop directory. This is a generic value. On systems with no concept of a desktop, this is the same as QStandardPaths::HomeLocation.
QStandardPaths::DocumentsLocation	1	Returns the directory containing user document files. This is a generic value. The returned path is never empty.
QStandardPaths::FontsLocation	2	Returns the directory containing user's fonts. This is a generic value. Note that installing fonts may require additional, platform-specific operations.
QStandardPaths::ApplicationsLocation	3	Returns the directory containing the user applications (either executables, application bundles, or shortcuts to them). This is a generic value. Note that installing applications may require additional, platform-specific operations. Files, folders or shortcuts in this directory are platform-specific.
QStandardPaths::MusicLocation	4	Returns the directory containing the user's music or other audio files. This is a generic value. If no directory specific for music files exists, a sensible fallback for storing user documents is returned.
QStandardPaths::MoviesLocation	5	Returns the directory containing the user's movies and videos. This is a generic value. If no directory specific for movie files exists, a sensible fallback for storing user documents is returned.
QStandardPaths::PicturesLocation	6	Returns the directory containing the user's pictures or photos. This is a generic value. If no directory specific for picture files exists, a sensible fallback for storing user documents is returned.
QStandardPaths::TempLocation	7	Returns a directory where temporary files can be stored. The returned value might be application-specific, shared among other applications for this user, or even system-wide. The returned path is never empty.
QStandardPaths::HomeLocation	8	Returns the user's home directory (the same as ()). On Unix systems, this is equal to the HOME environment variable. This value might be generic or application-specific, but the returned path is never empty.
QStandardPaths::DataLocation	9	Returns a directory location where persistent application data can be stored. This is an application-specific directory. To obtain a path to store data to be shared with other applications, use QStandardPaths::GenericDataLocation. The returned path is never empty.
QStandardPaths::CacheLocation	10	Returns a directory location where user-specific non-essential (cached) data should be written. This is an application-specific directory. The returned path is never empty.
QStandardPaths::GenericCacheLocation	15	Returns a directory location where user-specific non-essential (cached) data, shared across applications, should be written. This is a generic value. Note that the returned path may be empty if the system has no concept of shared cache.
QStandardPaths::GenericDataLocation	11	Returns a directory location where persistent data shared across applications can be stored. This is a generic value. The returned path is never empty.
QStandardPaths::RuntimeLocation	12	Returns a directory location where runtime communication files should be written, like Unix local sockets. This is a generic value. The returned path may be empty on some systems.
QStandardPaths::ConfigLocation	13	Returns a directory location where user-specific configuration files should be written. This may be either a generic value or application-specific, and the returned path is never empty.
QStandardPaths::DownloadLocation	14	Returns a directory for user's downloaded files. This is a generic value. If no directory specific for downloads exists, a sensible fallback for storing user documents is returned.
QStandardPaths::GenericConfigLocation	16	Returns a directory location where user-specific configuration files shared between multiple applications should be written. This is a generic value and the returned path is never empty.

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