source: trunk/doc/src/deployment/qt-conf.qdoc@ 814

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/*!
    \page qt-conf.html

    \title Using qt.conf

    The \c qt.conf file overrides the hard-coded paths that are
    compiled into the Qt library. These paths are accessible using the
    QLibraryInfo class. Without \c qt.conf, the functions in
    QLibraryInfo return these hard-coded paths; otherwise they return
    the paths as specified in \c qt.conf.

    Without \c qt.conf, the Qt libraries will use the hard-coded paths
    to look for plugins, translations, and so on. These paths may not
    exist on the target system, or they may not be
    accesssible. Because of this, you need \c qt.conf to make the Qt
    libraries look elsewhere.

        Note that on OS/2, the libraries do not use the hard-coded paths
        by default. Instead, they look for plugins and other components in a
        directory that contains the QtCore DLL library (or the application
        executable if Qt is built as a static library). This behavior may
        also be overridden using the \c qt.conf file.
    
    QLibraryInfo will load \c qt.conf from one of the following locations:

    \list 1

    \o \c :/qt/etc/qt.conf using the resource system

    \o on Mac OS X, in the Resource directory inside the appliction
    bundle, for example \c assistant.app/Contents/Resources/qt.conf

    \o in the directory containing the application executable, i.e.
    QCoreApplication::applicationDirPath() + QDir::separator() + "qt.conf"

    \endlist

    On OS/2, if neither of the above locations contains \c qt.conf,
    QLibraryInfo will additionally try the following locations, in the
    given order:

    \list 1

    \o \c qt.conf in the directory containing the QtCore DLL library
    (or the application executable if Qt is built as a static library)

    \o hard-coded system-wide \c .conf file (if set by the given build
    of the Qt library)
    
    \o \c %ETC%\qt.conf
    
    \endlist
    
    The \c qt.conf file is an INI text file, as described in the \l
    {QSettings::Format}{QSettings} documentation. The file should have
    a \c Paths group which contains the entries that correspond to
    each value of the QLibraryInfo::LibraryLocation enum. See the
    QLibraryInfo documentation for details on the meaning of the
    various locations.

    \table

    \header \o Entry            \o Default Value

    \row \o Prefix              \o QCoreApplication::applicationDirPath()
    \row \o Documentation       \o \c doc
    \row \o Headers             \o \c include
    \row \o Libraries           \o \c lib
    \row \o Binaries            \o \c bin
    \row \o Plugins             \o \c plugins
    \row \o Data                \o \c .
    \row \o Translations        \o \c translations
    \row \o Settings            \o \c .
    \row \o Examples            \o \c .
    \row \o Demos               \o \c .

    \endtable

    Absolute paths are used as specified in the \c qt.conf file. All
    paths are relative to the \c Prefix. On Windows and X11, the \c
    Prefix is relative to the directory containing the application
    executable (QCoreApplication::applicationDirPath()). On Mac OS X,
    the \c Prefix is relative to the \c Contents in the application
    bundle. For example, \c application.app/Contents/plugins/ is the
    default location for loading Qt plugins. Note that the plugins
    need to be placed in specific sub-directories under the
    \c{plugins} directory (see \l{How to Create Qt Plugins} for
    details). On OS/2, the \c Prefix is always relative to the directory
    where \c qt.conf or \c qtsys.conf is loaded from.
    
    For example, a \c qt.conf file could contain the following:

    \snippet doc/src/snippets/code/doc_src_qt-conf.qdoc 0

    Subgroups of the \c Paths group may be used to specify locations
    for specific versions of the Qt libraries. Such subgroups are of
    the form \c Paths/x.y.z, where x is the major version of the Qt
    libraries, y the minor, and z the patch level. The subgroup that
    most closely matches the current Qt version is used. If no
    subgroup matches, the \c Paths group is used as the fallback. The
    minor and patch level values may be omitted, in which case they
    default to zero.

    For example, given the following groups:

    \snippet doc/src/snippets/code/doc_src_qt-conf.qdoc 1

    The current version will be matched as shown: