qlayout.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qlayout.h"
 
#include "qapplication.h"
#include "qlayoutengine_p.h"
#if QT_CONFIG(menubar)
#include "qmenubar.h"
#endif
#if QT_CONFIG(toolbar)
#include "qtoolbar.h"
#endif
#if QT_CONFIG(sizegrip)
#include "qsizegrip.h"
#endif
#include "qevent.h"
#include "qstyle.h"
#include "qvariant.h"
#include "qwidget_p.h"
#include "qlayout_p.h"
 
QT_BEGIN_NAMESPACE
 
static int menuBarHeightForWidth(QWidget *menubar, int w)
{
    if (menubar && !menubar->isHidden() && !menubar->isWindow()) {
        int result = menubar->heightForWidth(qMax(w, menubar->minimumWidth()));
        if (result == -1)
            result = menubar->sizeHint().height();
        const int min = qSmartMinSize(menubar).height();
        result = qBound(min, result, menubar->maximumSize().height());
        if (result != -1)
            return result;
    }
    return 0;
}
 
QLayout::QLayout(QWidget *parent)
    : QObject(*new QLayoutPrivate, parent)
{
    if (!parent)
        return;
    parent->setLayout(this);
}
 
QLayout::QLayout(QLayoutPrivate &dd, QLayout *lay, QWidget *w)
    : QObject(dd, lay ? static_cast<QObject*>(lay) : static_cast<QObject*>(w))
{
    Q_D(QLayout);
    if (lay) {
        lay->addItem(this);
    } else if (w) {
        if (Q_UNLIKELY(w->layout())) {
            qWarning("QLayout: Attempting to add QLayout \"%ls\" to %s \"%ls\", which"
                     " already has a layout",
                     qUtf16Printable(QObject::objectName()), w->metaObject()->className(),
                     qUtf16Printable(w->objectName()));
            setParent(nullptr);
        } else {
            d->topLevel = true;
            w->d_func()->layout = this;
            QT_TRY {
                invalidate();
            } QT_CATCH(...) {
                w->d_func()->layout = nullptr;
                QT_RETHROW;
            }
        }
    }
}
 
QLayoutPrivate::QLayoutPrivate()
    : QObjectPrivate(), insideSpacing(-1), userLeftMargin(-1), userTopMargin(-1), userRightMargin(-1),
      userBottomMargin(-1), topLevel(false), enabled(true), activated(true), autoNewChild(false),
      constraint(QLayout::SetDefaultConstraint), menubar(nullptr)
{
}
 
void QLayoutPrivate::getMargin(int *result, int userMargin, QStyle::PixelMetric pm) const
{
    if (!result)
        return;
 
    Q_Q(const QLayout);
    if (userMargin >= 0) {
        *result = userMargin;
    } else if (!topLevel) {
        *result = 0;
    } else if (QWidget *pw = q->parentWidget()) {
        *result = pw->style()->pixelMetric(pm, nullptr, pw);
    } else {
        *result = 0;
    }
}
 
// Static item factory functions that allow for hooking things in Designer
 
QLayoutPrivate::QWidgetItemFactoryMethod QLayoutPrivate::widgetItemFactoryMethod = nullptr;
QLayoutPrivate::QSpacerItemFactoryMethod QLayoutPrivate::spacerItemFactoryMethod = nullptr;
 
QWidgetItem *QLayoutPrivate::createWidgetItem(const QLayout *layout, QWidget *widget)
{
    if (widgetItemFactoryMethod)
        if (QWidgetItem *wi = (*widgetItemFactoryMethod)(layout, widget))
            return wi;
    return new QWidgetItemV2(widget);
}
 
QSpacerItem *QLayoutPrivate::createSpacerItem(const QLayout *layout, int w, int h, QSizePolicy::Policy hPolicy, QSizePolicy::Policy vPolicy)
{
    if (spacerItemFactoryMethod)
        if (QSpacerItem *si = (*spacerItemFactoryMethod)(layout, w, h, hPolicy, vPolicy))
            return si;
    return new QSpacerItem(w, h,  hPolicy, vPolicy);
}
 
 
 
void QLayout::addWidget(QWidget *w)
{
    addChildWidget(w);
    addItem(QLayoutPrivate::createWidgetItem(this, w));
}
 
 
 
bool QLayout::setAlignment(QWidget *w, Qt::Alignment alignment)
{
    int i = 0;
    QLayoutItem *item = itemAt(i);
    while (item) {
        if (item->widget() == w) {
            item->setAlignment(alignment);
            invalidate();
            return true;
        }
        ++i;
        item = itemAt(i);
    }
    return false;
}
 
bool QLayout::setAlignment(QLayout *l, Qt::Alignment alignment)
{
    int i = 0;
    QLayoutItem *item = itemAt(i);
    while (item) {
        if (item->layout() == l) {
            item->setAlignment(alignment);
            invalidate();
            return true;
        }
        ++i;
        item = itemAt(i);
    }
    return false;
}
 
int QLayout::spacing() const
{
    Q_D(const QLayout);
    if (d->insideSpacing >=0) {
        return d->insideSpacing;
    } else {
        // arbitrarily prefer horizontal spacing to vertical spacing
        return qSmartSpacing(this, QStyle::PM_LayoutHorizontalSpacing);
    }
}
 
void QLayout::setSpacing(int spacing)
{
    Q_D(QLayout);
    d->insideSpacing = spacing;
    invalidate();
}
 
void QLayout::setContentsMargins(int left, int top, int right, int bottom)
{
    Q_D(QLayout);
 
    if (d->userLeftMargin == left && d->userTopMargin == top &&
        d->userRightMargin == right && d->userBottomMargin == bottom)
        return;
 
    d->userLeftMargin = left;
    d->userTopMargin = top;
    d->userRightMargin = right;
    d->userBottomMargin = bottom;
    invalidate();
}
 
void QLayout::setContentsMargins(const QMargins &margins)
{
    setContentsMargins(margins.left(), margins.top(), margins.right(), margins.bottom());
}
 
void QLayout::unsetContentsMargins()
{
    setContentsMargins(-1, -1, -1, -1);
}
 
void QLayout::getContentsMargins(int *left, int *top, int *right, int *bottom) const
{
    Q_D(const QLayout);
    d->getMargin(left, d->userLeftMargin, QStyle::PM_LayoutLeftMargin);
    d->getMargin(top, d->userTopMargin, QStyle::PM_LayoutTopMargin);
    d->getMargin(right, d->userRightMargin, QStyle::PM_LayoutRightMargin);
    d->getMargin(bottom, d->userBottomMargin, QStyle::PM_LayoutBottomMargin);
}
 
QMargins QLayout::contentsMargins() const
{
    int left, top, right, bottom;
    getContentsMargins(&left, &top, &right, &bottom);
    return QMargins(left, top, right, bottom);
}
 
QRect QLayout::contentsRect() const
{
    Q_D(const QLayout);
    int left, top, right, bottom;
    getContentsMargins(&left, &top, &right, &bottom);
    return d->rect.adjusted(+left, +top, -right, -bottom);
}
 
 
QWidget *QLayout::parentWidget() const
{
    Q_D(const QLayout);
    if (!d->topLevel) {
        if (parent()) {
            QLayout *parentLayout = qobject_cast<QLayout*>(parent());
            if (Q_UNLIKELY(!parentLayout)) {
                qWarning("QLayout::parentWidget: A layout can only have another layout as a parent.");
                return nullptr;
            }
            return parentLayout->parentWidget();
        } else {
            return nullptr;
        }
    } else {
        Q_ASSERT(parent() && parent()->isWidgetType());
        return static_cast<QWidget *>(parent());
    }
}
 
bool QLayout::isEmpty() const
{
    int i = 0;
    QLayoutItem *item = itemAt(i);
    while (item) {
        if (!item->isEmpty())
            return false;
        ++i;
        item = itemAt(i);
    }
    return true;
}
 
QSizePolicy::ControlTypes QLayout::controlTypes() const
{
    if (count() == 0)
        return QSizePolicy::DefaultType;
    QSizePolicy::ControlTypes types;
    for (int i = count() - 1; i >= 0; --i)
        types |= itemAt(i)->controlTypes();
    return types;
}
 
void QLayout::setGeometry(const QRect &r)
{
    Q_D(QLayout);
    d->rect = r;
}
 
QRect QLayout::geometry() const
{
    Q_D(const QLayout);
    return d->rect;
}
 
void QLayout::invalidate()
{
    Q_D(QLayout);
    d->rect = QRect();
    update();
}
 
static bool removeWidgetRecursively(QLayoutItem *li, QObject *w)
{
    QLayout *lay = li->layout();
    if (!lay)
        return false;
    int i = 0;
    QLayoutItem *child;
    while ((child = lay->itemAt(i))) {
        if (child->widget() == w) {
            delete lay->takeAt(i);
            lay->invalidate();
            return true;
        } else if (removeWidgetRecursively(child, w)) {
            return true;
        } else {
            ++i;
        }
    }
    return false;
}
 
 
void QLayoutPrivate::doResize()
{
    Q_Q(QLayout);
    QWidget *mw = q->parentWidget();
    QRect rect = mw->testAttribute(Qt::WA_LayoutOnEntireRect) ? mw->rect() : mw->contentsRect();
    const int mbh = menuBarHeightForWidth(menubar, rect.width());
    const int mbTop = rect.top();
    rect.setTop(mbTop + mbh);
    q->setGeometry(rect);
#if QT_CONFIG(menubar)
    if (menubar)
        menubar->setGeometry(rect.left(), mbTop, rect.width(), mbh);
#endif
}
 
 
void QLayout::widgetEvent(QEvent *e)
{
    Q_D(QLayout);
    if (!d->enabled)
        return;
 
    switch (e->type()) {
    case QEvent::Resize:
        if (d->activated)
            d->doResize();
        else
            activate();
        break;
    case QEvent::ChildRemoved:
        {
            QChildEvent *c = (QChildEvent *)e;
            QObject *child = c->child();
            QObjectPrivate *op = QObjectPrivate::get(child);
            if (op->wasWidget) {
#if QT_CONFIG(menubar)
                if (child == d->menubar)
                    d->menubar = nullptr;
#endif
                removeWidgetRecursively(this, child);
            }
        }
        break;
    case QEvent::LayoutRequest:
        if (static_cast<QWidget *>(parent())->isVisible())
            activate();
        break;
    default:
        break;
    }
}
 
void QLayout::childEvent(QChildEvent *e)
{
    Q_D(QLayout);
    if (!d->enabled)
        return;
 
    if (e->type() != QEvent::ChildRemoved)
        return;
 
    if (QLayout *childLayout = qobject_cast<QLayout *>(e->child()))
        removeItem(childLayout);
}
 
int QLayout::totalMinimumHeightForWidth(int w) const
{
    Q_D(const QLayout);
    int side=0, top=0;
    if (d->topLevel) {
        QWidget *parent = parentWidget();
        parent->ensurePolished();
        QWidgetPrivate *wd = parent->d_func();
        side += wd->leftmargin + wd->rightmargin;
        top += wd->topmargin + wd->bottommargin;
    }
    int h = minimumHeightForWidth(w - side) + top;
#if QT_CONFIG(menubar)
    h += menuBarHeightForWidth(d->menubar, w);
#endif
    return h;
}
 
int QLayout::totalHeightForWidth(int w) const
{
    Q_D(const QLayout);
    int side=0, top=0;
    if (d->topLevel) {
        QWidget *parent = parentWidget();
        parent->ensurePolished();
        QWidgetPrivate *wd = parent->d_func();
        side += wd->leftmargin + wd->rightmargin;
        top += wd->topmargin + wd->bottommargin;
    }
    int h = heightForWidth(w - side) + top;
#if QT_CONFIG(menubar)
    h += menuBarHeightForWidth(d->menubar, w);
#endif
    return h;
}
 
QSize QLayout::totalMinimumSize() const
{
    Q_D(const QLayout);
    int side=0, top=0;
    if (d->topLevel) {
        QWidget *pw = parentWidget();
        pw->ensurePolished();
        QWidgetPrivate *wd = pw->d_func();
        side += wd->leftmargin + wd->rightmargin;
        top += wd->topmargin + wd->bottommargin;
    }
 
    QSize s = minimumSize();
#if QT_CONFIG(menubar)
    top += menuBarHeightForWidth(d->menubar, s.width() + side);
#endif
    return s + QSize(side, top);
}
 
QSize QLayout::totalSizeHint() const
{
    Q_D(const QLayout);
    int side=0, top=0;
    if (d->topLevel) {
        QWidget *pw = parentWidget();
        pw->ensurePolished();
        QWidgetPrivate *wd = pw->d_func();
        side += wd->leftmargin + wd->rightmargin;
        top += wd->topmargin + wd->bottommargin;
    }
 
    QSize s = sizeHint();
    if (hasHeightForWidth())
        s.setHeight(heightForWidth(s.width() + side));
#if QT_CONFIG(menubar)
    top += menuBarHeightForWidth(d->menubar, s.width());
#endif
    return s + QSize(side, top);
}
 
QSize QLayout::totalMaximumSize() const
{
    Q_D(const QLayout);
    int side=0, top=0;
    if (d->topLevel) {
        QWidget *pw = parentWidget();
        pw->ensurePolished();
        QWidgetPrivate *wd = pw->d_func();
        side += wd->leftmargin + wd->rightmargin;
        top += wd->topmargin + wd->bottommargin;
    }
 
    QSize s = maximumSize();
#if QT_CONFIG(menubar)
    top += menuBarHeightForWidth(d->menubar, s.width());
#endif
 
    if (d->topLevel)
        s = QSize(qMin(s.width() + side, QLAYOUTSIZE_MAX),
                   qMin(s.height() + top, QLAYOUTSIZE_MAX));
    return s;
}
 
QLayout::~QLayout()
{
    Q_D(QLayout);
    if (d->topLevel && parent() && parent()->isWidgetType() && parentWidget()->layout() == this)
        parentWidget()->d_func()->layout = nullptr;
    else if (QLayout *parentLayout = qobject_cast<QLayout *>(parent()))
        parentLayout->removeItem(this);
}
 
 
void QLayout::addChildLayout(QLayout *childLayout)
{
    if (Q_UNLIKELY(childLayout->parent())) {
        qWarning("QLayout::addChildLayout: layout %s \"%ls\" already has a parent",
                 childLayout->metaObject()->className(), qUtf16Printable(childLayout->objectName()));
        return;
    }
    childLayout->setParent(this);
 
    if (QWidget *mw = parentWidget()) {
        childLayout->d_func()->reparentChildWidgets(mw);
    }
 
}
 
bool QLayout::adoptLayout(QLayout *layout)
{
    const bool ok = !layout->parent();
    addChildLayout(layout);
    return ok;
}
 
#ifdef QT_DEBUG
static bool layoutDebug()
{
    static int checked_env = -1;
    if (checked_env == -1)
        checked_env = !!qEnvironmentVariableIntValue("QT_LAYOUT_DEBUG");
 
    return checked_env;
}
#endif
 
void QLayoutPrivate::reparentChildWidgets(QWidget *mw)
{
    Q_Q(QLayout);
    int n =  q->count();
 
#if QT_CONFIG(menubar)
    if (menubar && menubar->parentWidget() != mw) {
        menubar->setParent(mw);
    }
#endif
    bool mwVisible = mw && mw->isVisible();
    for (int i = 0; i < n; ++i) {
        QLayoutItem *item = q->itemAt(i);
        if (QWidget *w = item->widget()) {
            QWidget *pw = w->parentWidget();
#ifdef QT_DEBUG
            if (Q_UNLIKELY(pw && pw != mw && layoutDebug())) {
                qWarning("QLayout::addChildLayout: widget %s \"%ls\" in wrong parent; moved to correct parent",
                         w->metaObject()->className(), qUtf16Printable(w->objectName()));
            }
#endif
            bool needShow = mwVisible && !(w->isHidden() && w->testAttribute(Qt::WA_WState_ExplicitShowHide));
            if (pw != mw)
                w->setParent(mw);
            if (needShow)
                QMetaObject::invokeMethod(w, "_q_showIfNotHidden", Qt::QueuedConnection); //show later
        } else if (QLayout *l = item->layout()) {
            l->d_func()->reparentChildWidgets(mw);
        }
    }
}
 
bool QLayoutPrivate::checkWidget(QWidget *widget) const
{
    Q_Q(const QLayout);
    if (Q_UNLIKELY(!widget)) {
        qWarning("QLayout: Cannot add a null widget to %s/%ls", q->metaObject()->className(),
                  qUtf16Printable(q->objectName()));
        return false;
    }
    if (Q_UNLIKELY(widget == q->parentWidget())) {
        qWarning("QLayout: Cannot add parent widget %s/%ls to its child layout %s/%ls",
                  widget->metaObject()->className(), qUtf16Printable(widget->objectName()),
                  q->metaObject()->className(), qUtf16Printable(q->objectName()));
        return false;
    }
    return true;
}
 
bool QLayoutPrivate::checkLayout(QLayout *otherLayout) const
{
    Q_Q(const QLayout);
    if (Q_UNLIKELY(!otherLayout)) {
        qWarning("QLayout: Cannot add a null layout to %s/%ls",
                 q->metaObject()->className(), qUtf16Printable(q->objectName()));
        return false;
    }
    if (Q_UNLIKELY(otherLayout == q)) {
        qWarning("QLayout: Cannot add layout %s/%ls to itself",
                 q->metaObject()->className(), qUtf16Printable(q->objectName()));
        return false;
    }
    return true;
}
 
void QLayout::addChildWidget(QWidget *w)
{
    QWidget *mw = parentWidget();
    QWidget *pw = w->parentWidget();
 
    //Qt::WA_LaidOut is never reset. It only means that the widget at some point has
    //been in a layout.
    if (pw && w->testAttribute(Qt::WA_LaidOut)) {
        QLayout *l = pw->layout();
        if (l && removeWidgetRecursively(l, w)) {
#ifdef QT_DEBUG
            if (Q_UNLIKELY(layoutDebug()))
                qWarning("QLayout::addChildWidget: %s \"%ls\" is already in a layout; moved to new layout",
                         w->metaObject()->className(), qUtf16Printable(w->objectName()));
#endif
        }
    }
    if (pw && mw && pw != mw) {
#ifdef QT_DEBUG
            if (Q_UNLIKELY(layoutDebug()))
                qWarning("QLayout::addChildWidget: %s \"%ls\" in wrong parent; moved to correct parent",
                         w->metaObject()->className(), qUtf16Printable(w->objectName()));
#endif
        pw = nullptr;
    }
    bool needShow = mw && mw->isVisible() && !(w->isHidden() && w->testAttribute(Qt::WA_WState_ExplicitShowHide));
    if (!pw && mw)
        w->setParent(mw);
    w->setAttribute(Qt::WA_LaidOut);
    if (needShow)
        QMetaObject::invokeMethod(w, "_q_showIfNotHidden", Qt::QueuedConnection); //show later
}
 
 
 
 
 
 
 
 
void QLayout::setMenuBar(QWidget *widget)
{
    Q_D(QLayout);
        if (widget)
            addChildWidget(widget);
    d->menubar = widget;
}
 
QWidget *QLayout::menuBar() const
{
    Q_D(const QLayout);
    return d->menubar;
}
 
 
QSize QLayout::minimumSize() const
{
    return QSize(0, 0);
}
 
QSize QLayout::maximumSize() const
{
    return QSize(QLAYOUTSIZE_MAX, QLAYOUTSIZE_MAX);
}
 
Qt::Orientations QLayout::expandingDirections() const
{
    return Qt::Horizontal | Qt::Vertical;
}
 
void QLayout::activateRecursiveHelper(QLayoutItem *item)
{
    item->invalidate();
    QLayout *layout = item->layout();
    if (layout) {
        QLayoutItem *child;
        int i=0;
        while ((child = layout->itemAt(i++)))
            activateRecursiveHelper(child);
        layout->d_func()->activated = true;
    }
}
 
void QLayout::update()
{
    QLayout *layout = this;
    while (layout && layout->d_func()->activated) {
        layout->d_func()->activated = false;
        if (layout->d_func()->topLevel) {
            Q_ASSERT(layout->parent()->isWidgetType());
            QWidget *mw = static_cast<QWidget*>(layout->parent());
            QCoreApplication::postEvent(mw, new QEvent(QEvent::LayoutRequest));
            break;
        }
        layout = static_cast<QLayout*>(layout->parent());
    }
}
 
bool QLayout::activate()
{
    Q_D(QLayout);
    if (!d->enabled || !parent())
        return false;
    if (!d->topLevel)
        return static_cast<QLayout*>(parent())->activate();
    if (d->activated)
        return false;
    QWidget *mw = static_cast<QWidget*>(parent());
    if (Q_UNLIKELY(!mw)) {
        qWarning("QLayout::activate: %s \"%ls\" does not have a main widget",
                 metaObject()->className(), qUtf16Printable(objectName()));
        return false;
    }
    activateRecursiveHelper(this);
 
    QWidgetPrivate *md = mw->d_func();
    uint explMin = md->extra ? md->extra->explicitMinSize : 0;
    uint explMax = md->extra ? md->extra->explicitMaxSize : 0;
 
    switch (d->constraint) {
    case SetFixedSize:
        // will trigger resize
        mw->setFixedSize(totalSizeHint());
        break;
    case SetMinimumSize:
        mw->setMinimumSize(totalMinimumSize());
        break;
    case SetMaximumSize:
        mw->setMaximumSize(totalMaximumSize());
        break;
    case SetMinAndMaxSize:
        mw->setMinimumSize(totalMinimumSize());
        mw->setMaximumSize(totalMaximumSize());
        break;
    case SetDefaultConstraint: {
        bool widthSet = explMin & Qt::Horizontal;
        bool heightSet = explMin & Qt::Vertical;
        if (mw->isWindow()) {
            QSize ms = totalMinimumSize();
            if (widthSet)
                ms.setWidth(mw->minimumSize().width());
            if (heightSet)
                ms.setHeight(mw->minimumSize().height());
            mw->setMinimumSize(ms);
        } else if (!widthSet || !heightSet) {
            QSize ms = mw->minimumSize();
            if (!widthSet)
                ms.setWidth(0);
            if (!heightSet)
                ms.setHeight(0);
            mw->setMinimumSize(ms);
        }
        break;
    }
    case SetNoConstraint:
        break;
    }
 
    d->doResize();
 
    if (md->extra) {
        md->extra->explicitMinSize = explMin;
        md->extra->explicitMaxSize = explMax;
    }
    // ideally only if sizeHint() or sizePolicy() has changed
    mw->updateGeometry();
    return true;
}
 
QLayoutItem *QLayout::replaceWidget(QWidget *from, QWidget *to, Qt::FindChildOptions options)
{
    Q_D(QLayout);
    if (!from || !to)
        return nullptr;
    if (from == to)     // Do not return a QLayoutItem for \a from, since ownership still
        return nullptr; // belongs to the layout (since nothing was changed)
 
    int index = -1;
    QLayoutItem *item = nullptr;
    for (int u = 0; u < count(); ++u) {
        item = itemAt(u);
        if (!item)
            continue;
 
        if (item->widget() == from) {
            index = u;
            break;
        }
 
        if (item->layout() && (options & Qt::FindChildrenRecursively)) {
            QLayoutItem *r = item->layout()->replaceWidget(from, to, options);
            if (r)
                return r;
        }
    }
    if (index == -1)
        return nullptr;
 
    addChildWidget(to);
    QLayoutItem *newitem = new QWidgetItem(to);
    newitem->setAlignment(item->alignment());
    QLayoutItem *r = d->replaceAt(index, newitem);
    if (!r)
        delete newitem;
    return r;
}
 
int QLayout::indexOf(const QWidget *widget) const
{
    const int c = count();
 
    for (int i = 0; i < c; ++i) {
        if (itemAt(i)->widget() == widget)
            return i;
    }
 
    return -1;
}
 
int QLayout::indexOf(const QLayoutItem *layoutItem) const
{
    const int c = count();
 
    for (int i = 0; i < c; ++i) {
        if (itemAt(i) == layoutItem)
            return i;
    }
 
    return -1;
}
 
void QLayout::setSizeConstraint(SizeConstraint constraint)
{
    Q_D(QLayout);
    if (constraint == d->constraint)
        return;
 
    d->constraint = constraint;
    invalidate();
}
 
QLayout::SizeConstraint QLayout::sizeConstraint() const
{
    Q_D(const QLayout);
    return d->constraint;
}
 
QRect QLayout::alignmentRect(const QRect &r) const
{
    QSize s = sizeHint();
    Qt::Alignment a = alignment();
 
    /*
      This is a hack to obtain the real maximum size, not
      QSize(QLAYOUTSIZE_MAX, QLAYOUTSIZE_MAX), the value consistently
      returned by QLayoutItems that have an alignment.
    */
    QLayout *that = const_cast<QLayout *>(this);
    that->setAlignment({ });
    QSize ms = that->maximumSize();
    that->setAlignment(a);
 
    if ((expandingDirections() & Qt::Horizontal) ||
         !(a & Qt::AlignHorizontal_Mask)) {
        s.setWidth(qMin(r.width(), ms.width()));
    }
    if ((expandingDirections() & Qt::Vertical) ||
         !(a & Qt::AlignVertical_Mask)) {
        s.setHeight(qMin(r.height(), ms.height()));
    } else if (hasHeightForWidth()) {
        int hfw = heightForWidth(s.width());
        if (hfw < s.height())
            s.setHeight(qMin(hfw, ms.height()));
    }
 
    s = s.boundedTo(r.size());
    int x = r.x();
    int y = r.y();
 
    if (a & Qt::AlignBottom)
        y += (r.height() - s.height());
    else if (!(a & Qt::AlignTop))
        y += (r.height() - s.height()) / 2;
 
    QWidget *parent = parentWidget();
    a = QStyle::visualAlignment(parent ? parent->layoutDirection() : QGuiApplication::layoutDirection(), a);
    if (a & Qt::AlignRight)
        x += (r.width() - s.width());
    else if (!(a & Qt::AlignLeft))
        x += (r.width() - s.width()) / 2;
 
    return QRect(x, y, s.width(), s.height());
}
 
void QLayout::removeWidget(QWidget *widget)
{
    if (Q_UNLIKELY(!widget)) {
        qWarning("QLayout::removeWidget: Cannot remove a null widget.");
        return;
    }
 
    int i = 0;
    QLayoutItem *child;
    while ((child = itemAt(i))) {
        if (child->widget() == widget) {
            delete takeAt(i);
            invalidate();
        } else {
            ++i;
        }
    }
}
 
void QLayout::removeItem(QLayoutItem *item)
{
    int i = 0;
    QLayoutItem *child;
    while ((child = itemAt(i))) {
        if (child == item) {
            takeAt(i);
            invalidate();
        } else {
            ++i;
        }
    }
}
 
void QLayout::setEnabled(bool enable)
{
    Q_D(QLayout);
    d->enabled = enable;
}
 
bool QLayout::isEnabled() const
{
    Q_D(const QLayout);
    return d->enabled;
}
 
QSize QLayout::closestAcceptableSize(const QWidget *widget, const QSize &size)
{
    QSize result = size.boundedTo(qSmartMaxSize(widget));
    result = result.expandedTo(qSmartMinSize(widget));
    QLayout *l = widget->layout();
    if (l && l->hasHeightForWidth() && result.height() < l->minimumHeightForWidth(result.width()) ) {
        QSize current = widget->size();
        int currentHfw =  l->minimumHeightForWidth(current.width());
        int newHfw = l->minimumHeightForWidth(result.width());
        if (current.height() < currentHfw || currentHfw == newHfw) {
            //handle the constant hfw case and the vertical-only case, as well as the
            // current-size-is-not-correct case
            result.setHeight(newHfw);
        } else {
            // binary search; assume hfw is decreasing ###
 
            int maxw = qMax(widget->width(),result.width());
            int maxh = qMax(widget->height(), result.height());
            int minw = qMin(widget->width(),result.width());
            int minh = qMin(widget->height(), result.height());
 
            int minhfw = l->minimumHeightForWidth(minw);
            int maxhfw = l->minimumHeightForWidth(maxw);
            while (minw < maxw) {
                if (minhfw > maxh) { //assume decreasing
                    minw = maxw - (maxw-minw)/2;
                    minhfw = l->minimumHeightForWidth(minw);
                } else if (maxhfw < minh ) { //assume decreasing
                    maxw = minw + (maxw-minw)/2;
                    maxhfw = l->minimumHeightForWidth(maxw);
                } else  {
                    break;
                }
            }
            result = result.expandedTo(QSize(minw, minhfw));
        }
    }
    return result;
}
 
QT_END_NAMESPACE
 
#include "moc_qlayout.cpp"