[C++知识库]Qt源码分析--QWidget(1)--Window functions

1.void show();

/*!
    Shows the widget and its child widgets.
    This is equivalent to calling showFullScreen(), showMaximized(), or setVisible(true),
    depending on the platform's default behavior for the window flags.
     \sa raise(), showEvent(), hide(), setVisible(), showMinimized(), showMaximized(),
    showNormal(), isVisible(), windowFlags()
*/
void QWidget::show()
{
    Qt::WindowState defaultState = QGuiApplicationPrivate::platformIntegration()->defaultWindowState(data->window_flags);
    if (defaultState == Qt::WindowFullScreen)
        showFullScreen();
    else if (defaultState == Qt::WindowMaximized)
        showMaximized();
    else
        setVisible(true); // Don't call showNormal() as not to clobber Qt::Window(Max/Min)imized
}

/*!
    Shows the widget in full-screen mode.
    Calling this function only affects \l{isWindow()}{windows}.
    To return from full-screen mode, call showNormal().
    Full-screen mode works fine under Windows, but has certain
    problems under X. These problems are due to limitations of the
    ICCCM protocol that specifies the communication between X11
    clients and the window manager. ICCCM simply does not understand
    the concept of non-decorated full-screen windows. Therefore, the
    best we can do is to request a borderless window and place and
    resize it to fill the entire screen. Depending on the window
    manager, this may or may not work. The borderless window is
    requested using MOTIF hints, which are at least partially
    supported by virtually all modern window managers.
    An alternative would be to bypass the window manager entirely and
    create a window with the Qt::X11BypassWindowManagerHint flag. This
    has other severe problems though, like totally broken keyboard focus
    and very strange effects on desktop changes or when the user raises
    other windows.
    X11 window managers that follow modern post-ICCCM specifications
    support full-screen mode properly.
    \sa showNormal(), showMaximized(), show(), hide(), isVisible()
*/
void QWidget::showFullScreen()
{
    ensurePolished();
    setWindowState((windowState() & ~(Qt::WindowMinimized | Qt::WindowMaximized))
                   | Qt::WindowFullScreen);
    setVisible(true);
#if !defined Q_OS_QNX // On QNX this window will be activated anyway from libscreen
                      // activating it here before libscreen activates it causes problems
    activateWindow();
#endif
}

根据窗口状态不同， 做不同的展示。

2.void hide();

/*!
    Hides the widget. This function is equivalent to
    setVisible(false).
    \note If you are working with QDialog or its subclasses and you invoke
    the show() function after this function, the dialog will be displayed in
    its original position.
    \sa hideEvent(), isHidden(), show(), setVisible(), isVisible(), close()
*/
void QWidget::hide()
{
    setVisible(false);
}

void QWidget::setVisible(bool visible)
{
    if (testAttribute(Qt::WA_WState_ExplicitShowHide) && testAttribute(Qt::WA_WState_Hidden) == !visible)
        return;
    // Remember that setVisible was called explicitly
    setAttribute(Qt::WA_WState_ExplicitShowHide);
    Q_D(QWidget);
    d->setVisible(visible);
}

void QWidgetPrivate::setVisible(bool visible)
{
    Q_Q(QWidget);
    if (visible) { // show
        // Designer uses a trick to make grabWidget work without showing
        if (!q->isWindow() && q->parentWidget() && q->parentWidget()->isVisible()
            && !q->parentWidget()->testAttribute(Qt::WA_WState_Created))
            q->parentWidget()->window()->d_func()->createRecursively();
        //create toplevels but not children of non-visible parents
        QWidget *pw = q->parentWidget();
        if (!q->testAttribute(Qt::WA_WState_Created)
            && (q->isWindow() || pw->testAttribute(Qt::WA_WState_Created))) {
            q->create();
        }
        bool wasResized = q->testAttribute(Qt::WA_Resized);
        Qt::WindowStates initialWindowState = q->windowState();
        // polish if necessary
        q->ensurePolished();
        // whether we need to inform the parent widget immediately
        bool needUpdateGeometry = !q->isWindow() && q->testAttribute(Qt::WA_WState_Hidden);
        // we are no longer hidden
        q->setAttribute(Qt::WA_WState_Hidden, false);
        if (needUpdateGeometry)
            updateGeometry_helper(true);
        // activate our layout before we and our children become visible
        if (layout)
            layout->activate();
        if (!q->isWindow()) {
            QWidget *parent = q->parentWidget();
            while (parent && parent->isVisible() && parent->d_func()->layout  && !parent->data->in_show) {
                parent->d_func()->layout->activate();
                if (parent->isWindow())
                    break;
                parent = parent->parentWidget();
            }
            if (parent)
                parent->d_func()->setDirtyOpaqueRegion();
        }
        // adjust size if necessary
        if (!wasResized
            && (q->isWindow() || !q->parentWidget()->d_func()->layout))  {
            if (q->isWindow()) {
                q->adjustSize();
                if (q->windowState() != initialWindowState)
                    q->setWindowState(initialWindowState);
            } else {
                q->adjustSize();
            }
            q->setAttribute(Qt::WA_Resized, false);
        }
        q->setAttribute(Qt::WA_KeyboardFocusChange, false);
        if (q->isWindow() || q->parentWidget()->isVisible()) {
            show_helper();
            qApp->d_func()->sendSyntheticEnterLeave(q);
        }
        QEvent showToParentEvent(QEvent::ShowToParent);
        QCoreApplication::sendEvent(q, &showToParentEvent);
    } else { // hide
        if (QApplicationPrivate::hidden_focus_widget == q)
            QApplicationPrivate::hidden_focus_widget = nullptr;
        // hw: The test on getOpaqueRegion() needs to be more intelligent
        // currently it doesn't work if the widget is hidden (the region will
        // be clipped). The real check should be testing the cached region
        // (and dirty flag) directly.
        if (!q->isWindow() && q->parentWidget()) // && !d->getOpaqueRegion().isEmpty())
            q->parentWidget()->d_func()->setDirtyOpaqueRegion();
        if (!q->testAttribute(Qt::WA_WState_Hidden)) {
            q->setAttribute(Qt::WA_WState_Hidden);
            if (q->testAttribute(Qt::WA_WState_Created))
                hide_helper();
        }
        // invalidate layout similar to updateGeometry()
        if (!q->isWindow() && q->parentWidget()) {
            if (q->parentWidget()->d_func()->layout)
                q->parentWidget()->d_func()->layout->invalidate();
            else if (q->parentWidget()->isVisible())
                QCoreApplication::postEvent(q->parentWidget(), new QEvent(QEvent::LayoutRequest));
        }
        QEvent hideToParentEvent(QEvent::HideToParent);
        QCoreApplication::sendEvent(q, &hideToParentEvent);
    }
}

void QWidgetPrivate::hide_helper()
{
    Q_Q(QWidget);
    bool isEmbedded = false;
#if QT_CONFIG(graphicsview)
    isEmbedded = q->isWindow() && !bypassGraphicsProxyWidget(q) && nearestGraphicsProxyWidget(q->parentWidget()) != nullptr;
#else
    Q_UNUSED(isEmbedded);
#endif
    if (!isEmbedded && (q->windowType() == Qt::Popup))
        qApp->d_func()->closePopup(q);
    q->setAttribute(Qt::WA_Mapped, false);
    hide_sys();
    bool wasVisible = q->testAttribute(Qt::WA_WState_Visible);
    if (wasVisible) {
        q->setAttribute(Qt::WA_WState_Visible, false);
    }
    QHideEvent hideEvent;
    QCoreApplication::sendEvent(q, &hideEvent);
    hideChildren(false);
    // next bit tries to move the focus if the focus widget is now
    // hidden.
    if (wasVisible) {
        qApp->d_func()->sendSyntheticEnterLeave(q);
        QWidget *fw = QApplication::focusWidget();
        while (fw &&  !fw->isWindow()) {
            if (fw == q) {
                q->focusNextPrevChild(true);
                break;
            }
            fw = fw->parentWidget();
        }
    }
    if (QWidgetRepaintManager *repaintManager = maybeRepaintManager())
        repaintManager->removeDirtyWidget(q);
#ifndef QT_NO_ACCESSIBILITY
    if (wasVisible) {
        QAccessibleEvent event(q, QAccessible::ObjectHide);
        QAccessible::updateAccessibility(&event);
    }
#endif
}

将窗口从刷新列表中清除，隐藏窗口。

3.void raise();

void QWidget::raise()
{
    Q_D(QWidget);
    if (!isWindow()) {
        QWidget *p = parentWidget();
        const int parentChildCount = p->d_func()->children.size();
        if (parentChildCount < 2)
            return;
        const int from = p->d_func()->children.indexOf(this);
        Q_ASSERT(from >= 0);
        // Do nothing if the widget is already in correct stacking order _and_ created.
        if (from != parentChildCount -1)
            p->d_func()->children.move(from, parentChildCount - 1);
        if (!testAttribute(Qt::WA_WState_Created) && p->testAttribute(Qt::WA_WState_Created))
            create();
        else if (from == parentChildCount - 1)
            return;
        QRegion region(rect());
        d->subtractOpaqueSiblings(region);
        d->invalidateBackingStore(region);
    }
    if (testAttribute(Qt::WA_WState_Created))
        d->raise_sys();
    if (d->extra && d->extra->hasWindowContainer)
        QWindowContainer::parentWasRaised(this);
    QEvent e(QEvent::ZOrderChange);
    QCoreApplication::sendEvent(this, &e);
}

void QWidgetPrivate::raise_sys()
{
    Q_Q(QWidget);
    if (q->isWindow() || q->testAttribute(Qt::WA_NativeWindow)) {
        q->windowHandle()->raise();
    } else if (renderToTexture) {
        if (QWidget *p = q->parentWidget()) {
            setDirtyOpaqueRegion();
            p->d_func()->invalidateBackingStore(effectiveRectFor(q->geometry()));
        }
    }
}

void QWindow::raise()
{
    Q_D(QWindow);
    d->updateSiblingPosition(QWindowPrivate::PositionTop);
    if (d->platformWindow)
        d->platformWindow->raise();
}

4.void lower();

/*!
    Lower the window in the windowing system.
    Requests that the window be lowered to appear below other windows.
*/
void QWindow::lower()
{
    Q_D(QWindow);
    d->updateSiblingPosition(QWindowPrivate::PositionBottom);
    if (d->platformWindow)
        d->platformWindow->lower();
}

5.bool close();

/*!
    Close the window.
    This closes the window, effectively calling destroy(), and potentially
    quitting the application. Returns \c true on success, false if it has a parent
    window (in which case the top level window should be closed instead).
    \sa destroy(), QGuiApplication::quitOnLastWindowClosed(), closeEvent()
*/
bool QWindow::close()
{
    Q_D(QWindow);
    // Do not close non top level windows
    if (parent())
        return false;
    if (!d->platformWindow)
        return true;
    return d->platformWindow->close();
}