src/gui/widgets/qabstractscrollarea.cpp

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/****************************************************************************
**
** Copyright (C) 1992-2006 Trolltech ASA. All rights reserved.
**
** This file is part of the QtGui module of the Qt Toolkit.
**
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** and appearing in the file LICENSE.GPL included in the packaging of
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#include "qabstractscrollarea.h"

#ifndef QT_NO_SCROLLAREA

#include "qscrollbar.h"
#include "qapplication.h"
#include "qstyle.h"
#include "qstyleoption.h"
#include "qevent.h"
#include "qdebug.h"
#include "qboxlayout.h"
#include "qpainter.h"

#include "qabstractscrollarea_p.h"
#include <qwidget.h>

#ifdef Q_WS_MAC
#include <qmacstyle_mac.h>
#include <private/qt_mac_p.h>
#endif

QAbstractScrollAreaPrivate::QAbstractScrollAreaPrivate()
    :hbar(0), vbar(0), vbarpolicy(Qt::ScrollBarAsNeeded), hbarpolicy(Qt::ScrollBarAsNeeded),
     viewport(0), cornerWidget(0), left(0), top(0), right(0), bottom(0),
     xoffset(0), yoffset(0), viewportFilter(0)
{
}

QAbstractScrollAreaScrollBarContainer::QAbstractScrollAreaScrollBarContainer(Qt::Orientation orientation, QWidget *parent)
    :QWidget(parent), scrollBar(new QScrollBar(orientation, this)),
     layout(new QBoxLayout(orientation == Qt::Horizontal ? QBoxLayout::LeftToRight : QBoxLayout::TopToBottom)),
     orientation(orientation)
{
    setLayout(layout);
    layout->setMargin(0);
    layout->setSpacing(0);
    layout->addWidget(scrollBar);
}

void QAbstractScrollAreaScrollBarContainer::addWidget(QWidget *widget, LogicalPosition position)
{
    QSizePolicy policy = widget->sizePolicy();
    if (orientation == Qt::Vertical)
        policy.setHorizontalPolicy(QSizePolicy::Ignored);
    else
        policy.setVerticalPolicy(QSizePolicy::Ignored);
    widget->setSizePolicy(policy);
    widget->setParent(this);

    const int insertIndex = (position & LogicalLeft) ? 0 : scrollBarLayoutIndex() + 1;
    layout->insertWidget(insertIndex, widget);
}

QWidgetList QAbstractScrollAreaScrollBarContainer::widgets(LogicalPosition position)
{
    QWidgetList list;
    const int scrollBarIndex = scrollBarLayoutIndex();
    if (position == LogicalLeft) {
        for (int i = 0; i < scrollBarIndex; ++i)
            list.append(layout->itemAt(i)->widget());
    } else if (position == LogicalRight) {
        const int layoutItemCount = layout->count();
        for (int i = scrollBarIndex + 1; i < layoutItemCount; ++i)
            list.append(layout->itemAt(i)->widget());
    }
    return list;
}

int QAbstractScrollAreaScrollBarContainer::scrollBarLayoutIndex() const
{
    const int layoutItemCount = layout->count();
    for (int i = 0; i < layoutItemCount; ++i) {
        if (qobject_cast<QScrollBar *>(layout->itemAt(i)->widget()))
            return i;
    }
    return -1;
}

void QAbstractScrollAreaPrivate::replaceScrollBar(QScrollBar *scrollBar,
                                                  Qt::Orientation orientation)
{
    Q_Q(QAbstractScrollArea);

    QAbstractScrollAreaScrollBarContainer *container = scrollBarContainers[orientation];
    bool horizontal = (orientation == Qt::Horizontal);
    QScrollBar *oldBar = horizontal ? hbar : vbar;
    if (horizontal)
        hbar = scrollBar;
    else
        vbar = scrollBar;
    scrollBar->setParent(container);
    container->scrollBar = scrollBar;
    container->layout->removeWidget(oldBar);
    container->layout->insertWidget(0, scrollBar);
    scrollBar->setVisible(oldBar->isVisible());
    scrollBar->setInvertedAppearance(oldBar->invertedAppearance());
    scrollBar->setInvertedControls(oldBar->invertedControls());
    scrollBar->setRange(oldBar->minimum(), oldBar->maximum());
    scrollBar->setOrientation(oldBar->orientation());
    scrollBar->setPageStep(oldBar->pageStep());
    scrollBar->setSingleStep(oldBar->singleStep());
    scrollBar->setSliderDown(oldBar->isSliderDown());
    scrollBar->setSliderPosition(oldBar->sliderPosition());
    scrollBar->setTracking(oldBar->hasTracking());
    scrollBar->setValue(oldBar->value());
    delete oldBar;

    QObject::connect(scrollBar, SIGNAL(valueChanged(int)),
                     q, horizontal ? SLOT(_q_hslide(int)) : SLOT(_q_vslide(int)));
    QObject::connect(scrollBar, SIGNAL(rangeChanged(int,int)),
                     q, SLOT(_q_showOrHideScrollBars()), Qt::QueuedConnection);
}

void QAbstractScrollAreaPrivate::init()
{
    Q_Q(QAbstractScrollArea);
    scrollBarContainers[Qt::Horizontal] = new QAbstractScrollAreaScrollBarContainer(Qt::Horizontal, q);
    hbar = scrollBarContainers[Qt::Horizontal]->scrollBar;
    hbar->setRange(0,0);
    scrollBarContainers[Qt::Horizontal]->setVisible(false);
    QObject::connect(hbar, SIGNAL(valueChanged(int)), q, SLOT(_q_hslide(int)));
    QObject::connect(hbar, SIGNAL(rangeChanged(int,int)), q, SLOT(_q_showOrHideScrollBars()), Qt::QueuedConnection);
    scrollBarContainers[Qt::Vertical] = new QAbstractScrollAreaScrollBarContainer(Qt::Vertical, q);
    vbar = scrollBarContainers[Qt::Vertical]->scrollBar;
    vbar->setRange(0,0);
    scrollBarContainers[Qt::Vertical]->setVisible(false);
    QObject::connect(vbar, SIGNAL(valueChanged(int)), q, SLOT(_q_vslide(int)));
    QObject::connect(vbar, SIGNAL(rangeChanged(int,int)), q, SLOT(_q_showOrHideScrollBars()), Qt::QueuedConnection);
    viewportFilter = new QAbstractScrollAreaFilter(this);
    viewport = new QWidget(q);
    viewport->setObjectName(QLatin1String("qt_scrollarea_viewport"));
    viewport->setBackgroundRole(QPalette::Base);
    viewport->setAutoFillBackground(true);
    viewport->installEventFilter(viewportFilter);
    viewport->setFocusProxy(q);
    q->setFocusPolicy(Qt::WheelFocus);
    q->setFrameStyle(QFrame::StyledPanel | QFrame::Sunken);
    q->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
    layoutChildren();
}

void QAbstractScrollAreaPrivate::layoutChildren()
{
    Q_Q(QAbstractScrollArea);
    bool needh = (hbarpolicy == Qt::ScrollBarAlwaysOn
                  || (hbarpolicy == Qt::ScrollBarAsNeeded && hbar->minimum() < hbar->maximum()));

    bool needv = (vbarpolicy == Qt::ScrollBarAlwaysOn
                  || (vbarpolicy == Qt::ScrollBarAsNeeded && vbar->minimum() < vbar->maximum()));

    const int hsbExt = hbar->sizeHint().height();
    const int vsbExt = vbar->sizeHint().width();
    const QPoint extPoint(vsbExt, hsbExt);
    const QSize extSize(vsbExt, hsbExt);

    const QRect widgetRect = q->rect();
    QStyleOption opt(0);
    opt.init(q);

    const bool hasCornerWidget = (cornerWidget != 0);

// If the scroll bars are at the very right and bottom of the window we
// move their positions to be aligned with the size grip.
#ifdef Q_WS_MAC
    QWidget * const window = q->window();
    // Check if a native sizegrip is present.
    bool hasMacReverseSizeGrip = false;
    bool hasMacSizeGrip = false;
    HIViewRef nativeSizeGrip;
    HIViewFindByID(HIViewGetRoot(HIViewGetWindow(HIViewRef(q->winId()))), kHIViewWindowGrowBoxID, &nativeSizeGrip);
    if (nativeSizeGrip) {
        // Look for a native size grip at the visual window bottom right and at the
        // absolute window bottom right. In reverse mode, the native size grip does not
        // swich side, so we need to check if it is on the "wrong side".
        const QPoint scrollAreaBottomRight = q->mapTo(window, widgetRect.bottomRight() - QPoint(frameWidth, frameWidth));
        const QPoint windowBottomRight = window->rect().bottomRight();
        const QPoint visualWindowBottomRight = QStyle::visualPos(opt.direction, opt.rect, windowBottomRight);
        const QPoint offset = windowBottomRight - scrollAreaBottomRight;
        const QPoint visualOffset = visualWindowBottomRight - scrollAreaBottomRight;
        hasMacSizeGrip = (visualOffset.manhattanLength() < vsbExt);
        hasMacReverseSizeGrip = (hasMacSizeGrip == false && (offset.manhattanLength() < hsbExt));
    }

    // Use small scroll bars for tool windows, if the window has a native size grip.
    const QMacStyle::WidgetSizePolicy hpolicy = QMacStyle::widgetSizePolicy(hbar);
    const QMacStyle::WidgetSizePolicy vpolicy = QMacStyle::widgetSizePolicy(vbar);
    const Qt::WindowType windowType = window->windowType();
    if (windowType == Qt::Tool && (hasMacSizeGrip || hasMacReverseSizeGrip)) {
        if (hpolicy != QMacStyle::SizeSmall)
            QMacStyle::setWidgetSizePolicy(hbar, QMacStyle::SizeSmall);
        if (vpolicy != QMacStyle::SizeSmall)
            QMacStyle::setWidgetSizePolicy(vbar, QMacStyle::SizeSmall);
    } else {
        if (hpolicy != QMacStyle::SizeDefault)
            QMacStyle::setWidgetSizePolicy(hbar, QMacStyle::SizeDefault);
        if (vpolicy != QMacStyle::SizeDefault)
            QMacStyle::setWidgetSizePolicy(vbar, QMacStyle::SizeDefault);
    }
#endif
    QPoint cornerOffset(needv ? vsbExt : 0, needh ? hsbExt : 0);
    QRect controlsRect;
    QRect viewportRect;

    // In FrameOnlyAroundContents mode the frame is drawn between the controls and
    // the viewport, else the frame rect is equal to the widget rect.
    if (q->style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, &opt, q)) {
        controlsRect = widgetRect;
        const int extra = q->style()->pixelMetric(QStyle::PM_DefaultFrameWidth) * 2;
        const QPoint cornerExtra(needv ? extra : 0, needh ? extra : 0);
        QRect frameRect = widgetRect;
        frameRect.adjust(0, 0, -cornerOffset.x() - cornerExtra.x(), -cornerOffset.y() - cornerExtra.y());
        q->setFrameRect(frameRect);
        viewportRect = q->contentsRect();
    } else {
        q->setFrameRect(QStyle::visualRect(opt.direction, opt.rect, widgetRect));
        controlsRect = q->contentsRect();
        viewportRect = QRect(controlsRect.topLeft(), controlsRect.bottomRight() - cornerOffset);
    }

    // If we have a corner widget and are only showing one scroll bar, we need to move it
    // to make room for the corner widget.
    if (hasCornerWidget && (needv || needh))
        cornerOffset =  extPoint;

#ifdef Q_WS_MAC
    // Also move the scroll bars if they are covered by the native Mac size grip.
    if (hasMacSizeGrip)
        cornerOffset =  extPoint;
#endif

    // The corner point is where the scroll bar rects, the corner widget rect and the
    // viewport rect meets.
    const QPoint cornerPoint(controlsRect.bottomRight() + QPoint(1, 1) - cornerOffset);

    // Some styles paints the corner if both scorllbars are showing and there is
    // no corner widget. Also, on the Mac we paint if there is a native
    // (transparent) sizegrip in the area where a corner widget would be.
    if (needv && needh && hasCornerWidget == false
#ifdef Q_WS_MAC
        || ((needv || needh) && hasMacSizeGrip)
#endif
    ) {
        cornerPaintingRect = QStyle::visualRect(opt.direction, opt.rect, QRect(cornerPoint, extSize));
    } else {
        cornerPaintingRect = QRect();
    }

#ifdef Q_WS_MAC
    if (hasMacReverseSizeGrip)
        reverseCornerPaintingRect = QRect(controlsRect.bottomRight() + QPoint(1, 1) - extPoint, extSize);
    else
        reverseCornerPaintingRect = QRect();
#endif

    if (needh) {
        QRect horizontalScrollBarRect(QPoint(controlsRect.left(), cornerPoint.y()), QPoint(cornerPoint.x() - 1, controlsRect.bottom()));
#ifdef Q_WS_MAC
        if (hasMacReverseSizeGrip)
            horizontalScrollBarRect.adjust(vsbExt, 0, 0, 0);
#endif
        scrollBarContainers[Qt::Horizontal]->setGeometry(QStyle::visualRect(opt.direction, opt.rect, horizontalScrollBarRect));
        scrollBarContainers[Qt::Horizontal]->raise();
    }

    if (needv) {
        const QRect verticalScrollBarRect  (QPoint(cornerPoint.x(), controlsRect.top()),  QPoint(controlsRect.right(), cornerPoint.y() - 1));
        scrollBarContainers[Qt::Vertical]->setGeometry(QStyle::visualRect(opt.direction, opt.rect, verticalScrollBarRect));
        scrollBarContainers[Qt::Vertical]->raise();
    }

    if (cornerWidget) {
        const QRect cornerWidgetRect(cornerPoint, controlsRect.bottomRight());
        cornerWidget->setGeometry(QStyle::visualRect(opt.direction, opt.rect, cornerWidgetRect));
    }

    scrollBarContainers[Qt::Horizontal]->setVisible(needh);
    scrollBarContainers[Qt::Vertical]->setVisible(needv);

    // Existing code expect to have to account for reverse mode when calling
    // setViewportMargins(), so we undo that here to preserve the behavior.
    // ### Qt 5: Consider changing the behavior.
    if (QApplication::isRightToLeft())
        viewportRect.adjust(right, top, -left, -bottom);
    else
        viewportRect.adjust(left, top, -right, -bottom);

    viewport->setGeometry(QStyle::visualRect(opt.direction, opt.rect, viewportRect)); // resize the viewport last
}

QAbstractScrollArea::QAbstractScrollArea(QAbstractScrollAreaPrivate &dd, QWidget *parent)
    :QFrame(dd, parent)
{
    Q_D(QAbstractScrollArea);
    d->init();
}

QAbstractScrollArea::QAbstractScrollArea(QWidget *parent)
    :QFrame(*new QAbstractScrollAreaPrivate, parent)
{
    Q_D(QAbstractScrollArea);
    d->init();
}


QAbstractScrollArea::~QAbstractScrollArea()
{
    Q_D(QAbstractScrollArea);
    delete d->viewportFilter;
}


void QAbstractScrollArea::setViewport(QWidget *widget)
{
    Q_D(QAbstractScrollArea);
    if (widget != d->viewport) {
        QWidget *oldViewport = d->viewport;
        if (!widget)
            widget = new QWidget;
        d->viewport = widget;
        d->viewport->setParent(this);
        d->viewport->setFocusProxy(this);
        d->viewport->installEventFilter(d->viewportFilter);
        d->layoutChildren();
        if (isVisible())
            d->viewport->show();
        QMetaObject::invokeMethod(this, "setupViewport", Q_ARG(QWidget *, widget));
        delete oldViewport;
    }
}

QWidget *QAbstractScrollArea::viewport() const
{
    Q_D(const QAbstractScrollArea);
    return d->viewport;
}


// ### still thinking about the name
QSize QAbstractScrollArea::maximumViewportSize() const
{
    Q_D(const QAbstractScrollArea);
    int hsbExt = d->hbar->sizeHint().height();
    int vsbExt = d->vbar->sizeHint().width();

    int f = 2 * d->frameWidth;
    QSize max = size() - QSize(f + d->left + d->right, f + d->top + d->bottom);
    if (d->vbarpolicy == Qt::ScrollBarAlwaysOn)
        max.rwidth() -= vsbExt;
    if (d->hbarpolicy == Qt::ScrollBarAlwaysOn)
        max.rheight() -= hsbExt;
    return max;
}

Qt::ScrollBarPolicy QAbstractScrollArea::verticalScrollBarPolicy() const
{
    Q_D(const QAbstractScrollArea);
    return d->vbarpolicy;
}

void QAbstractScrollArea::setVerticalScrollBarPolicy(Qt::ScrollBarPolicy policy)
{
    Q_D(QAbstractScrollArea);
    d->vbarpolicy = policy;
    if (isVisible())
        d->layoutChildren();
}


QScrollBar *QAbstractScrollArea::verticalScrollBar() const
{
    Q_D(const QAbstractScrollArea);
    return d->vbar;
}

void QAbstractScrollArea::setVerticalScrollBar(QScrollBar *scrollBar)
{
    Q_D(QAbstractScrollArea);
    if (!scrollBar) {
        qWarning("QAbstractScrollArea::setVerticalScrollBar: Cannot set a null scroll bar");
        return;
    }

    d->replaceScrollBar(scrollBar, Qt::Vertical);
}

Qt::ScrollBarPolicy QAbstractScrollArea::horizontalScrollBarPolicy() const
{
    Q_D(const QAbstractScrollArea);
    return d->hbarpolicy;
}

void QAbstractScrollArea::setHorizontalScrollBarPolicy(Qt::ScrollBarPolicy policy)
{
    Q_D(QAbstractScrollArea);
    d->hbarpolicy = policy;
    if (isVisible())
        d->layoutChildren();
}

QScrollBar *QAbstractScrollArea::horizontalScrollBar() const
{
    Q_D(const QAbstractScrollArea);
    return d->hbar;
}

void QAbstractScrollArea::setHorizontalScrollBar(QScrollBar *scrollBar)
{
    Q_D(QAbstractScrollArea);
    if (!scrollBar) {
        qWarning("QAbstractScrollArea::setHorizontalScrollBar: Cannot set a null scroll bar");
        return;
    }

    d->replaceScrollBar(scrollBar, Qt::Horizontal);
}

QWidget *QAbstractScrollArea::cornerWidget() const
{
    Q_D(const QAbstractScrollArea);
    return d->cornerWidget;
}

void QAbstractScrollArea::setCornerWidget(QWidget *widget)
{
    Q_D(QAbstractScrollArea);
    QWidget* oldWidget = d->cornerWidget;
    if (oldWidget != widget) {
        if (oldWidget)
            oldWidget->hide();
        d->cornerWidget = widget;

        if (widget && widget->parentWidget() != this)
            widget->setParent(this);

        d->layoutChildren();
        if (widget)
            widget->show();
    } else {
        d->cornerWidget = widget;
        d->layoutChildren();
    }
}

void QAbstractScrollArea::addScrollBarWidget(QWidget *widget, Qt::Alignment alignment)
{
    Q_D(QAbstractScrollArea);

    if (widget == 0)
        return;

    const Qt::Orientation scrollBarOrientation
        = ((alignment & Qt::AlignLeft) || (alignment & Qt::AlignRight)) ? Qt::Horizontal : Qt::Vertical;
    const QAbstractScrollAreaScrollBarContainer::LogicalPosition position
        = ((alignment & Qt::AlignRight) || (alignment & Qt::AlignBottom))
          ? QAbstractScrollAreaScrollBarContainer::LogicalRight : QAbstractScrollAreaScrollBarContainer::LogicalLeft;
    d->scrollBarContainers[scrollBarOrientation]->addWidget(widget, position);
    d->layoutChildren();
    if (isHidden() == false)
        widget->show();
}

QWidgetList QAbstractScrollArea::scrollBarWidgets(Qt::Alignment alignment)
{
    Q_D(QAbstractScrollArea);

    QWidgetList list;

    if (alignment & Qt::AlignLeft)
        list += d->scrollBarContainers[Qt::Horizontal]->widgets(QAbstractScrollAreaScrollBarContainer::LogicalLeft);
    if (alignment & Qt::AlignRight)
        list += d->scrollBarContainers[Qt::Horizontal]->widgets(QAbstractScrollAreaScrollBarContainer::LogicalRight);
    if (alignment & Qt::AlignTop)
        list += d->scrollBarContainers[Qt::Vertical]->widgets(QAbstractScrollAreaScrollBarContainer::LogicalLeft);
    if (alignment & Qt::AlignBottom)
        list += d->scrollBarContainers[Qt::Vertical]->widgets(QAbstractScrollAreaScrollBarContainer::LogicalRight);

    return list;
}

void QAbstractScrollArea::setViewportMargins(int left, int top, int right, int bottom)
{
    Q_D(QAbstractScrollArea);
    d->left = left;
    d->top = top;
    d->right = right;
    d->bottom = bottom;
    d->layoutChildren();
}

bool QAbstractScrollArea::event(QEvent *e)
{
    Q_D(QAbstractScrollArea);
    switch (e->type()) {
    case QEvent::AcceptDropsChange:
        d->viewport->setAcceptDrops(acceptDrops());
        break;
    case QEvent::MouseTrackingChange:
        d->viewport->setMouseTracking(hasMouseTracking());
        break;
    case QEvent::Resize:
            d->layoutChildren();
            break;
    case QEvent::Paint:
        if (d->cornerPaintingRect.isValid()) {
            QStyleOption option;
            option.rect = d->cornerPaintingRect;
            QPainter p(this);
            style()->drawPrimitive(QStyle::PE_PanelScrollAreaCorner, &option, &p, this);
        }
#ifdef Q_WS_MAC
        if (d->reverseCornerPaintingRect.isValid()) {
            QStyleOption option;
            option.rect = d->reverseCornerPaintingRect;
            QPainter p(this);
            style()->drawPrimitive(QStyle::PE_PanelScrollAreaCorner, &option, &p, this);
        }
#endif
        QFrame::paintEvent((QPaintEvent*)e);
        break;
    case QEvent::ContextMenu:
        if (static_cast<QContextMenuEvent *>(e)->reason() == QContextMenuEvent::Keyboard)
           return QFrame::event(e);
        e->ignore();
        break;
    case QEvent::MouseButtonPress:
    case QEvent::MouseButtonRelease:
    case QEvent::MouseButtonDblClick:
    case QEvent::MouseMove:
    case QEvent::Wheel:
#ifndef QT_NO_DRAGANDDROP
    case QEvent::Drop:
    case QEvent::DragEnter:
    case QEvent::DragMove:
    case QEvent::DragLeave:
#endif
        return false;
    case QEvent::StyleChange:
        d->layoutChildren();
        // fall through
    default:
        return QFrame::event(e);
    }
    return true;
}

bool QAbstractScrollArea::viewportEvent(QEvent *e)
{
    switch (e->type()) {
    case QEvent::Resize:
    case QEvent::Paint:
    case QEvent::MouseButtonPress:
    case QEvent::MouseButtonRelease:
    case QEvent::MouseButtonDblClick:
    case QEvent::MouseMove:
    case QEvent::ContextMenu:
#ifndef QT_NO_WHEELEVENT
    case QEvent::Wheel:
#endif
#ifndef QT_NO_DRAGANDDROP
    case QEvent::Drop:
    case QEvent::DragEnter:
    case QEvent::DragMove:
    case QEvent::DragLeave:
#endif
        return QFrame::event(e);
    case QEvent::LayoutRequest:
        return event(e);
    default:
        break;
    }
    return false; // let the viewport widget handle the event
}

void QAbstractScrollArea::resizeEvent(QResizeEvent *)
{
}

void QAbstractScrollArea::paintEvent(QPaintEvent*)
{
}

void QAbstractScrollArea::mousePressEvent(QMouseEvent *e)
{
    e->ignore();
}

void QAbstractScrollArea::mouseReleaseEvent(QMouseEvent *e)
{
    e->ignore();
}

void QAbstractScrollArea::mouseDoubleClickEvent(QMouseEvent *e)
{
    e->ignore();
}

void QAbstractScrollArea::mouseMoveEvent(QMouseEvent *e)
{
    e->ignore();
}

#ifndef QT_NO_WHEELEVENT
void QAbstractScrollArea::wheelEvent(QWheelEvent *e)
{
    Q_D(QAbstractScrollArea);
    if (static_cast<QWheelEvent*>(e)->orientation() == Qt::Horizontal)
        QApplication::sendEvent(d->hbar, e);
    else
        QApplication::sendEvent(d->vbar, e);
}
#endif

void QAbstractScrollArea::contextMenuEvent(QContextMenuEvent *e)
{
    e->ignore();
}

void QAbstractScrollArea::keyPressEvent(QKeyEvent * e)
{
    Q_D(QAbstractScrollArea);
    if (false){
#ifndef QT_NO_SHORTCUT
    } else if (e == QKeySequence::MoveToPreviousPage) {
        d->vbar->triggerAction(QScrollBar::SliderPageStepSub);
    } else if (e == QKeySequence::MoveToNextPage) {
        d->vbar->triggerAction(QScrollBar::SliderPageStepAdd);
#endif
    } else {
        switch (e->key()) {
        case Qt::Key_Up:
            d->vbar->triggerAction(QScrollBar::SliderSingleStepSub);
            break;
        case Qt::Key_Down:
            d->vbar->triggerAction(QScrollBar::SliderSingleStepAdd);
            break;
        case Qt::Key_Left:
            d->hbar->triggerAction(QScrollBar::SliderSingleStepSub);
            break;
        case Qt::Key_Right:
            d->hbar->triggerAction(QScrollBar::SliderSingleStepAdd);
            break;
        default:
            e->ignore();
            return;
        }
    }
    e->accept();
}


#ifndef QT_NO_DRAGANDDROP

void QAbstractScrollArea::dragEnterEvent(QDragEnterEvent *)
{
}

void QAbstractScrollArea::dragMoveEvent(QDragMoveEvent *)
{
}

void QAbstractScrollArea::dragLeaveEvent(QDragLeaveEvent *)
{
}

void QAbstractScrollArea::dropEvent(QDropEvent *)
{
}


#endif

void QAbstractScrollArea::scrollContentsBy(int, int)
{
    viewport()->update();
}

void QAbstractScrollAreaPrivate::_q_hslide(int x)
{
    Q_Q(QAbstractScrollArea);
    int dx = xoffset - x;
    xoffset = x;
    q->scrollContentsBy(dx, 0);
}

void QAbstractScrollAreaPrivate::_q_vslide(int y)
{
    Q_Q(QAbstractScrollArea);
    int dy = yoffset - y;
    yoffset = y;
    q->scrollContentsBy(0, dy);
}

void QAbstractScrollAreaPrivate::_q_showOrHideScrollBars()
{
    layoutChildren();
}

QPoint QAbstractScrollAreaPrivate::contentsOffset() const
{
    Q_Q(const QAbstractScrollArea);
    QPoint offset;
    if (vbar->isVisible())
        offset.setY(vbar->value());
    if (hbar->isVisible()) {
        if (q->isRightToLeft())
            offset.setX(hbar->maximum() - hbar->value());
        else
            offset.setX(hbar->value());
    }
    return offset;
}

QSize QAbstractScrollArea::minimumSizeHint() const
{
    Q_D(const QAbstractScrollArea);
    int hsbExt = d->hbar->sizeHint().height();
    int vsbExt = d->vbar->sizeHint().width();
    int extra = 2 * d->frameWidth;
    return QSize(d->scrollBarContainers[Qt::Horizontal]->sizeHint().width() + vsbExt + extra,
                 d->scrollBarContainers[Qt::Vertical]->sizeHint().height() + hsbExt + extra);
}

QSize QAbstractScrollArea::sizeHint() const
{
    return QSize(256, 192);
#if 0
    Q_D(const QAbstractScrollArea);
    int h = qMax(10, fontMetrics().height());
    int f = 2 * d->frameWidth;
    return QSize((6 * h) + f, (4 * h) + f);
#endif
}

void QAbstractScrollArea::setupViewport(QWidget *viewport)
{
    Q_UNUSED(viewport);
}

#include "moc_qabstractscrollarea.cpp"
#include "moc_qabstractscrollarea_p.cpp"
#endif // QT_NO_SCROLLAREA

---