qt-everywhere-src-5.14.1/qtdoc/doc/src/howtos/restoring-geometry.qdoc

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/*!
    \page restoring-geometry.html
    \title Restoring a Window's Geometry
    \brief How to save & restore window geometry.
    \ingroup best-practices

    This document describes how to save and restore a \l{Window
    Geometry}{window's geometry} using the geometry properties. On
    Windows, this is basically storing the result of
    QWindow::geometry() and calling QWindow::setGeometry() in the next
    session before calling \l{QWindow::show()}{show()}.

    On X11, this might not work because an invisible window does not
    have a frame yet. The window manager will decorate the window
    later.  When this happens, the window shifts towards the
    bottom/right corner of the screen depending on the size of the
    decoration frame.  Although X provides a way to avoid this shift,
    some window managers fail to implement this feature.

    When using \l{Qt Widgets}, Qt provides functions that saves and restores a
    widget window's geometry and state for you. QWidget::saveGeometry()
    saves the window geometry and maximized/fullscreen state, while
    QWidget::restoreGeometry() restores it. The restore function also
    checks if the restored geometry is outside the available screen
    geometry, and modifies it as appropriate if it is:

    \snippet snippets/code/src_gui_widgets_qmainwindow.cpp 0
    \snippet snippets/code/src_gui_widgets_qmainwindow.cpp 1

    Another solution is to store both \l{QWidget::pos()}{pos()} and
    \l{QWidget::size()}{size()} and to restore the geometry using
    \l{QWidget::resize()} and \l{QWidget::move()}{move()} before
    calling \l{QWidget::show()}{show()}, as demonstrated in the
    \l{mainwindows/application}{Application} example.
*/