qstackedlayout.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 "qstackedlayout.h"
#include "qlayout_p.h"
 
#include <qlist.h>
#include "private/qwidget_p.h"
#include "private/qlayoutengine_p.h"
 
#include <QtCore/qpointer.h>
 
#include <memory>
 
QT_BEGIN_NAMESPACE
 
class QStackedLayoutPrivate : public QLayoutPrivate
{
    Q_DECLARE_PUBLIC(QStackedLayout)
public:
    QStackedLayoutPrivate() : index(-1), stackingMode(QStackedLayout::StackOne) {}
    QLayoutItem* replaceAt(int index, QLayoutItem *newitem) override;
    QList<QLayoutItem *> list;
    int index;
    QStackedLayout::StackingMode stackingMode;
};
 
QLayoutItem* QStackedLayoutPrivate::replaceAt(int idx, QLayoutItem *newitem)
{
    Q_Q(QStackedLayout);
    if (idx < 0 || idx >= list.size() || !newitem)
        return nullptr;
    QWidget *wdg = newitem->widget();
    if (Q_UNLIKELY(!wdg)) {
        qWarning("QStackedLayout::replaceAt: Only widgets can be added");
        return nullptr;
    }
    QLayoutItem *orgitem = list.at(idx);
    list.replace(idx, newitem);
    if (idx == index)
        q->setCurrentIndex(index);
    return orgitem;
}
 
QStackedLayout::QStackedLayout()
    : QLayout(*new QStackedLayoutPrivate, nullptr, nullptr)
{
}
 
QStackedLayout::QStackedLayout(QWidget *parent)
    : QLayout(*new QStackedLayoutPrivate, nullptr, parent)
{
}
 
QStackedLayout::QStackedLayout(QLayout *parentLayout)
    : QLayout(*new QStackedLayoutPrivate, parentLayout, nullptr)
{
}
 
QStackedLayout::~QStackedLayout()
{
    Q_D(QStackedLayout);
    qDeleteAll(d->list);
}
 
int QStackedLayout::addWidget(QWidget *widget)
{
    Q_D(QStackedLayout);
    return insertWidget(d->list.size(), widget);
}
 
int QStackedLayout::insertWidget(int index, QWidget *widget)
{
    Q_D(QStackedLayout);
    addChildWidget(widget);
    index = qMin(index, d->list.size());
    if (index < 0)
        index = d->list.size();
    QWidgetItem *wi = QLayoutPrivate::createWidgetItem(this, widget);
    d->list.insert(index, wi);
    invalidate();
    if (d->index < 0) {
        setCurrentIndex(index);
    } else {
        if (index <= d->index)
            ++d->index;
        if (d->stackingMode == StackOne)
            widget->hide();
        widget->lower();
    }
    return index;
}
 
QLayoutItem *QStackedLayout::itemAt(int index) const
{
    Q_D(const QStackedLayout);
    return d->list.value(index);
}
 
// Code that enables proper handling of the case that takeAt() is
// called somewhere inside QObject destructor (can't call hide()
// on the object then)
static bool qt_wasDeleted(const QWidget *w)
{
    return QObjectPrivate::get(w)->wasDeleted;
}
 
 
QLayoutItem *QStackedLayout::takeAt(int index)
{
    Q_D(QStackedLayout);
    if (index <0 || index >= d->list.size())
        return nullptr;
    QLayoutItem *item = d->list.takeAt(index);
    if (index == d->index) {
        d->index = -1;
        if ( d->list.size() > 0 ) {
            int newIndex = (index == d->list.size()) ? index-1 : index;
            setCurrentIndex(newIndex);
        } else {
            emit currentChanged(-1);
        }
    } else if (index < d->index) {
        --d->index;
    }
    emit widgetRemoved(index);
    if (item->widget() && !qt_wasDeleted(item->widget()))
        item->widget()->hide();
    return item;
}
 
void QStackedLayout::setCurrentIndex(int index)
{
    Q_D(QStackedLayout);
    QWidget *prev = currentWidget();
    QWidget *next = widget(index);
    if (!next || next == prev)
        return;
 
    bool reenableUpdates = false;
    QWidget *parent = parentWidget();
 
    if (parent && parent->updatesEnabled()) {
        reenableUpdates = true;
        parent->setUpdatesEnabled(false);
    }
 
    QPointer<QWidget> fw = parent ? parent->window()->focusWidget() : nullptr;
    const bool focusWasOnOldPage = fw && (prev && prev->isAncestorOf(fw));
 
    if (prev) {
        prev->clearFocus();
        if (d->stackingMode == StackOne)
            prev->hide();
    }
 
    d->index = index;
    next->raise();
    next->show();
 
    // try to move focus onto the incoming widget if focus
    // was somewhere on the outgoing widget.
 
    if (parent) {
        if (focusWasOnOldPage) {
            // look for the best focus widget we can find
            if (QWidget *nfw = next->focusWidget())
                nfw->setFocus();
            else {
                // second best: first child widget in the focus chain
                if (QWidget *i = fw) {
                    while ((i = i->nextInFocusChain()) != fw) {
                        if (((i->focusPolicy() & Qt::TabFocus) == Qt::TabFocus)
                            && !i->focusProxy() && i->isVisibleTo(next) && i->isEnabled()
                            && next->isAncestorOf(i)) {
                            i->setFocus();
                            break;
                        }
                    }
                    // third best: incoming widget
                    if (i == fw )
                        next->setFocus();
                }
            }
        }
    }
    if (reenableUpdates)
        parent->setUpdatesEnabled(true);
    emit currentChanged(index);
}
 
int QStackedLayout::currentIndex() const
{
    Q_D(const QStackedLayout);
    return d->index;
}
 
 
void QStackedLayout::setCurrentWidget(QWidget *widget)
{
    int index = indexOf(widget);
    if (Q_UNLIKELY(index == -1)) {
        qWarning("QStackedLayout::setCurrentWidget: Widget %p not contained in stack", widget);
        return;
    }
    setCurrentIndex(index);
}
 
 
QWidget *QStackedLayout::currentWidget() const
{
    Q_D(const QStackedLayout);
    return d->index >= 0 ? d->list.at(d->index)->widget() : nullptr;
}
 
QWidget *QStackedLayout::widget(int index) const
{
    Q_D(const QStackedLayout);
     if (index < 0 || index >= d->list.size())
        return nullptr;
    return d->list.at(index)->widget();
}
 
int QStackedLayout::count() const
{
    Q_D(const QStackedLayout);
    return d->list.size();
}
 
 
void QStackedLayout::addItem(QLayoutItem *item)
{
    std::unique_ptr<QLayoutItem> guard(item);
    QWidget *widget = item->widget();
    if (Q_UNLIKELY(!widget)) {
        qWarning("QStackedLayout::addItem: Only widgets can be added");
        return;
    }
    addWidget(widget);
}
 
QSize QStackedLayout::sizeHint() const
{
    Q_D(const QStackedLayout);
    QSize s(0, 0);
    int n = d->list.size();
 
    for (int i = 0; i < n; ++i)
        if (QWidget *widget = d->list.at(i)->widget()) {
            QSize ws(widget->sizeHint());
            if (widget->sizePolicy().horizontalPolicy() == QSizePolicy::Ignored)
                ws.setWidth(0);
            if (widget->sizePolicy().verticalPolicy() == QSizePolicy::Ignored)
                ws.setHeight(0);
            s = s.expandedTo(ws);
        }
    return s;
}
 
QSize QStackedLayout::minimumSize() const
{
    Q_D(const QStackedLayout);
    QSize s(0, 0);
    int n = d->list.size();
 
    for (int i = 0; i < n; ++i)
        if (QWidget *widget = d->list.at(i)->widget())
            s = s.expandedTo(qSmartMinSize(widget));
    return s;
}
 
void QStackedLayout::setGeometry(const QRect &rect)
{
    Q_D(QStackedLayout);
    switch (d->stackingMode) {
    case StackOne:
        if (QWidget *widget = currentWidget())
            widget->setGeometry(rect);
        break;
    case StackAll:
        if (const int n = d->list.size())
            for (int i = 0; i < n; ++i)
                if (QWidget *widget = d->list.at(i)->widget())
                    widget->setGeometry(rect);
        break;
    }
}
 
bool QStackedLayout::hasHeightForWidth() const
{
    const int n = count();
 
    for (int i = 0; i < n; ++i) {
        if (QLayoutItem *item = itemAt(i)) {
            if (item->hasHeightForWidth())
                return true;
        }
    }
    return false;
}
 
int QStackedLayout::heightForWidth(int width) const
{
    const int n = count();
 
    int hfw = 0;
    for (int i = 0; i < n; ++i) {
        if (QLayoutItem *item = itemAt(i)) {
            if (QWidget *w = item->widget())
                /*
                Note: Does not query the layout item, but bypasses it and asks the widget
                directly. This is consistent with how QStackedLayout::sizeHint() is
                implemented. This also avoids an issue where QWidgetItem::heightForWidth()
                returns -1 if the widget is hidden.
                */
                hfw = qMax(hfw, w->heightForWidth(width));
        }
    }
    hfw = qMax(hfw, minimumSize().height());
    return hfw;
}
 
QStackedLayout::StackingMode QStackedLayout::stackingMode() const
{
    Q_D(const QStackedLayout);
    return d->stackingMode;
}
 
void QStackedLayout::setStackingMode(StackingMode stackingMode)
{
    Q_D(QStackedLayout);
    if (d->stackingMode == stackingMode)
        return;
    d->stackingMode = stackingMode;
 
    const int n = d->list.size();
    if (n == 0)
        return;
 
    switch (d->stackingMode) {
    case StackOne:
        if (const int idx = currentIndex())
            for (int i = 0; i < n; ++i)
                if (QWidget *widget = d->list.at(i)->widget())
                    widget->setVisible(i == idx);
        break;
    case StackAll: { // Turn overlay on: Make sure all widgets are the same size
        QRect geometry;
        if (const QWidget *widget = currentWidget())
            geometry = widget->geometry();
        for (int i = 0; i < n; ++i)
            if (QWidget *widget = d->list.at(i)->widget()) {
                if (!geometry.isNull())
                    widget->setGeometry(geometry);
                widget->setVisible(true);
            }
    }
        break;
    }
}
 
QT_END_NAMESPACE
 
#include "moc_qstackedlayout.cpp"