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#include "qapplication.h"

#include "qcursor.h"

#include "qevent.h"

#include "qpainter.h"

#include "qscrollbar.h"

#include "qstyle.h"

#include "qstyleoption.h"

#include "qmenu.h"

#ifndef QT_NO_SCROLLBAR

#ifndef QT_NO_ACCESSIBILITY

#include "qaccessible.h"

#endif

#include <limits.h>

#include "qabstractslider_p.h"

QT_BEGIN_NAMESPACE

/*!

    \class QScrollBar

    \brief The QScrollBar widget provides a vertical or horizontal scroll bar.

    \ingroup basicwidgets

    A scroll bar is a control that enables the user to access parts of a

    document that is larger than the widget used to display it. It provides

    a visual indication of the user's current position within the document

    and the amount of the document that is visible. Scroll bars are usually

    equipped with other controls that enable more accurate navigation.

    Qt displays scroll bars in a way that is appropriate for each platform.

    If you need to provide a scrolling view onto another widget, it may be

    more convenient to use the QScrollArea class because this provides a

    viewport widget and scroll bars. QScrollBar is useful if you need to

    implement similar functionality for specialized widgets using QAbstractScrollArea;

    for example, if you decide to subclass QAbstractItemView.

    For most other situations where a slider control is used to obtain a value

    within a given range, the QSlider class may be more appropriate for your

    needs.

    \table

    \row \i \image qscrollbar-picture.png

    \i Scroll bars typically include four separate controls: a slider,

    scroll arrows, and a page control.

    \list

    \i a. The slider provides a way to quickly go to any part of the

    document, but does not support accurate navigation within large

    documents.

    \i b. The scroll arrows are push buttons which can be used to accurately

    navigate to a particular place in a document. For a vertical scroll bar

    connected to a text editor, these typically move the current position one

    "line" up or down, and adjust the position of the slider by a small

    amount. In editors and list boxes a "line" might mean one line of text;

    in an image viewer it might mean 20 pixels.

    \i c. The page control is the area over which the slider is dragged (the

    scroll bar's background). Clicking here moves the scroll bar towards

    the click by one "page". This value is usually the same as the length of

    the slider.

    \endlist

    \endtable

    Each scroll bar has a value that indicates how far the slider is from

    the start of the scroll bar; this is obtained with value() and set

    with setValue(). This value always lies within the range of values

    defined for the scroll bar, from \l{QAbstractSlider::minimum()}{minimum()}

    to \l{QAbstractSlider::minimum()}{maximum()} inclusive. The range of

    acceptable values can be set with setMinimum() and setMaximum().

    At the minimum value, the top edge of the slider (for a vertical scroll

    bar) or left edge (for a horizontal scroll bar) will be at the top (or

    left) end of the scroll bar. At the maximum value, the bottom (or right)

    edge of the slider will be at the bottom (or right) end of the scroll bar.

    The length of the slider is usually related to the value of the page step,

    and typically represents the proportion of the document area shown in a

    scrolling view. The page step is the amount that the value changes by

    when the user presses the \key{Page Up} and \key{Page Down} keys, and is

    set with setPageStep(). Smaller changes to the value defined by the

    line step are made using the cursor keys, and this quantity is set with

    \l{QAbstractSlider::}{setSingleStep()}.

    Note that the range of values used is independent of the actual size

    of the scroll bar widget. You do not need to take this into account when

    you choose values for the range and the page step.

    The range of values specified for the scroll bar are often determined

    differently to those for a QSlider because the length of the slider

    needs to be taken into account. If we have a document with 100 lines,

    and we can only show 20 lines in a widget, we may wish to construct a

    scroll bar with a page step of 20, a minimum value of 0, and a maximum

    value of 80. This would give us a scroll bar with five "pages".

    \table

    \row \i \inlineimage qscrollbar-values.png

    \i The relationship between a document length, the range of values used

    in a scroll bar, and the page step is simple in many common situations.

    The scroll bar's range of values is determined by subtracting a

    chosen page step from some value representing the length of the document.

    In such cases, the following equation is useful:

    \e{document length} = maximum() - minimum() + pageStep().

    \endtable

    QScrollBar only provides integer ranges. Note that although

    QScrollBar handles very large numbers, scroll bars on current

    screens cannot usefully represent ranges above about 100,000 pixels.

    Beyond that, it becomes difficult for the user to control the

    slider using either the keyboard or the mouse, and the scroll

    arrows will have limited use.

    ScrollBar inherits a comprehensive set of signals from QAbstractSlider:

    \list

    \i \l{QAbstractSlider::valueChanged()}{valueChanged()} is emitted when the

       scroll bar's value has changed. The tracking() determines whether this

       signal is emitted during user interaction.

    \i \l{QAbstractSlider::rangeChanged()}{rangeChanged()} is emitted when the

       scroll bar's range of values has changed.

    \i \l{QAbstractSlider::sliderPressed()}{sliderPressed()} is emitted when

       the user starts to drag the slider.

    \i \l{QAbstractSlider::sliderMoved()}{sliderMoved()} is emitted when the user

       drags the slider.

    \i \l{QAbstractSlider::sliderReleased()}{sliderReleased()} is emitted when

       the user releases the slider.

    \i \l{QAbstractSlider::actionTriggered()}{actionTriggered()} is emitted

       when the scroll bar is changed by user interaction or via the

       \l{QAbstractSlider::triggerAction()}{triggerAction()} function.

    \endlist

    A scroll bar can be controlled by the keyboard, but it has a

    default focusPolicy() of Qt::NoFocus. Use setFocusPolicy() to

    enable keyboard interaction with the scroll bar:

    \list

         \i Left/Right move a horizontal scroll bar by one single step.

         \i Up/Down move a vertical scroll bar by one single step.

         \i PageUp moves up one page.

         \i PageDown moves down one page.

         \i Home moves to the start (mininum).

         \i End moves to the end (maximum).

     \endlist

    The slider itself can be controlled by using the

    \l{QAbstractSlider::triggerAction()}{triggerAction()} function to simulate

    user interaction with the scroll bar controls. This is useful if you have

    many different widgets that use a common range of values.

    Most GUI styles use the pageStep() value to calculate the size of the

    slider.

    \table 100%

    \row \o \inlineimage macintosh-horizontalscrollbar.png Screenshot of a Macintosh style scroll bar

         \o A scroll bar shown in the \l{Macintosh Style Widget Gallery}{Macintosh widget style}.

    \row \o \inlineimage windowsxp-horizontalscrollbar.png Screenshot of a Windows XP style scroll bar

         \o A scroll bar shown in the \l{Windows XP Style Widget Gallery}{Windows XP widget style}.

    \row \o \inlineimage plastique-horizontalscrollbar.png Screenshot of a Plastique style scroll bar

         \o A scroll bar shown in the \l{Plastique Style Widget Gallery}{Plastique widget style}.

    \endtable

    \sa QScrollArea, QSlider, QDial, QSpinBox, {fowler}{GUI Design Handbook: Scroll Bar}, {Sliders Example}

*/

class QScrollBarPrivate : public QAbstractSliderPrivate

{

    Q_DECLARE_PUBLIC(QScrollBar)

public:

    QStyle::SubControl pressedControl;

    bool pointerOutsidePressedControl;

    int clickOffset, snapBackPosition;

    void activateControl(uint control, int threshold = 500);

    void stopRepeatAction();

    int pixelPosToRangeValue(int pos) const;

    void init();

    bool updateHoverControl(const QPoint &pos);

    QStyle::SubControl newHoverControl(const QPoint &pos);

    QStyle::SubControl hoverControl;

    QRect hoverRect;

};

bool QScrollBarPrivate::updateHoverControl(const QPoint &pos)

{

    Q_Q(QScrollBar);

    QRect lastHoverRect = hoverRect;

    QStyle::SubControl lastHoverControl = hoverControl;

    bool doesHover = q->testAttribute(Qt::WA_Hover);

    if (lastHoverControl != newHoverControl(pos) && doesHover) {

        q->update(lastHoverRect);

        q->update(hoverRect);

        return true;

    }

    return !doesHover;

}

QStyle::SubControl QScrollBarPrivate::newHoverControl(const QPoint &pos)

{

    Q_Q(QScrollBar);

    QStyleOptionSlider opt;

    q->initStyleOption(&opt);

    opt.subControls = QStyle::SC_All;

    hoverControl = q->style()->hitTestComplexControl(QStyle::CC_ScrollBar, &opt, pos, q);

    if (hoverControl == QStyle::SC_None)

        hoverRect = QRect();

    else

        hoverRect = q->style()->subControlRect(QStyle::CC_ScrollBar, &opt, hoverControl, q);

    return hoverControl;

}

void QScrollBarPrivate::activateControl(uint control, int threshold)

{

    QAbstractSlider::SliderAction action = QAbstractSlider::SliderNoAction;

    switch (control) {

    case QStyle::SC_ScrollBarAddPage:

        action = QAbstractSlider::SliderPageStepAdd;

        break;

    case QStyle::SC_ScrollBarSubPage:

        action = QAbstractSlider::SliderPageStepSub;

        break;

    case QStyle::SC_ScrollBarAddLine:

        action = QAbstractSlider::SliderSingleStepAdd;

        break;

    case QStyle::SC_ScrollBarSubLine:

        action = QAbstractSlider::SliderSingleStepSub;

        break;

    case QStyle::SC_ScrollBarFirst:

        action = QAbstractSlider::SliderToMinimum;

        break;

    case QStyle::SC_ScrollBarLast:

        action = QAbstractSlider::SliderToMaximum;

        break;

    default:

        break;

    }

    if (action) {

        q_func()->setRepeatAction(action, threshold);

        q_func()->triggerAction(action);

    }

}

void QScrollBarPrivate::stopRepeatAction()

{

    Q_Q(QScrollBar);

    QStyle::SubControl tmp = pressedControl;

    q->setRepeatAction(QAbstractSlider::SliderNoAction);

    pressedControl = QStyle::SC_None;

    if (tmp == QStyle::SC_ScrollBarSlider)

        q->setSliderDown(false);

    QStyleOptionSlider opt;

    q->initStyleOption(&opt);

    q->repaint(q->style()->subControlRect(QStyle::CC_ScrollBar, &opt, tmp, q));

}

/*!

    Initialize \a option with the values from this QScrollBar. This method

    is useful for subclasses when they need a QStyleOptionSlider, but don't want

    to fill in all the information themselves.

    \sa QStyleOption::initFrom()

*/

void QScrollBar::initStyleOption(QStyleOptionSlider *option) const

{

    if (!option)

        return;

    Q_D(const QScrollBar);

    option->initFrom(this);

    option->subControls = QStyle::SC_None;

    option->activeSubControls = QStyle::SC_None;

    option->orientation = d->orientation;

    option->minimum = d->minimum;

    option->maximum = d->maximum;

    option->sliderPosition = d->position;

    option->sliderValue = d->value;

    option->singleStep = d->singleStep;

    option->pageStep = d->pageStep;

    option->upsideDown = d->invertedAppearance;

    if (d->orientation == Qt::Horizontal)

        option->state |= QStyle::State_Horizontal;

}

#define HORIZONTAL (d_func()->orientation == Qt::Horizontal)

#define VERTICAL !HORIZONTAL

/*!

    Constructs a vertical scroll bar.

    The \a parent arguments is sent to the QWidget constructor.

    The \l {QAbstractSlider::minimum} {minimum} defaults to 0, the

    \l {QAbstractSlider::maximum} {maximum} to 99, with a

    \l {QAbstractSlider::singleStep} {singleStep} size of 1 and a

    \l {QAbstractSlider::pageStep} {pageStep} size of 10, and an

    initial \l {QAbstractSlider::value} {value} of 0.

*/

QScrollBar::QScrollBar(QWidget *parent)

    : QAbstractSlider(*new QScrollBarPrivate, parent)

{

    d_func()->orientation = Qt::Vertical;

    d_func()->init();

}

/*!

    Constructs a scroll bar with the given \a orientation.

    The \a parent argument is passed to the QWidget constructor.

    The \l {QAbstractSlider::minimum} {minimum} defaults to 0, the

    \l {QAbstractSlider::maximum} {maximum} to 99, with a

    \l {QAbstractSlider::singleStep} {singleStep} size of 1 and a

    \l {QAbstractSlider::pageStep} {pageStep} size of 10, and an

    initial \l {QAbstractSlider::value} {value} of 0.

*/

QScrollBar::QScrollBar(Qt::Orientation orientation, QWidget *parent)

    : QAbstractSlider(*new QScrollBarPrivate, parent)

{

    d_func()->orientation = orientation;

    d_func()->init();

}

#ifdef QT3_SUPPORT

/*!

    Use one of the constructors that doesn't take the \a name

    argument and then use setObjectName() instead.

*/

QScrollBar::QScrollBar(QWidget *parent, const char *name)

    : QAbstractSlider(*new QScrollBarPrivate, parent)

{

    setObjectName(QString::fromAscii(name));

    d_func()->orientation = Qt::Vertical;

    d_func()->init();

}

/*!

    Use one of the constructors that doesn't take the \a name

    argument and then use setObjectName() instead.

*/

QScrollBar::QScrollBar(Qt::Orientation orientation, QWidget *parent, const char *name)

    : QAbstractSlider(*new QScrollBarPrivate, parent)

{

    setObjectName(QString::fromAscii(name));

    d_func()->orientation = orientation;

    d_func()->init();

}

/*!

    Use one of the constructors that doesn't take the \a name

    argument and then use setObjectName() instead.

*/

QScrollBar::QScrollBar(int minimum, int maximum, int lineStep, int pageStep,

                        int value, Qt::Orientation orientation,

                        QWidget *parent, const char *name)

    : QAbstractSlider(*new QScrollBarPrivate, parent)

{

    Q_D(QScrollBar);

    setObjectName(QString::fromAscii(name));

    d->minimum = minimum;

    d->maximum = maximum;

    d->singleStep = lineStep;

    d->pageStep = pageStep;

    d->value = value;

    d->orientation = orientation;

    d->init();

}

#endif // QT3_SUPPORT

/*!

    Destroys the scroll bar.

*/

QScrollBar::~QScrollBar()

{

}

void QScrollBarPrivate::init()

{

    Q_Q(QScrollBar);

    invertedControls = true;

    pressedControl = hoverControl = QStyle::SC_None;

    pointerOutsidePressedControl = false;

    q->setFocusPolicy(Qt::NoFocus);

    QSizePolicy sp(QSizePolicy::Minimum, QSizePolicy::Fixed, QSizePolicy::Slider);

    if (orientation == Qt::Vertical)

        sp.transpose();

    q->setSizePolicy(sp);

    q->setAttribute(Qt::WA_WState_OwnSizePolicy, false);

    q->setAttribute(Qt::WA_OpaquePaintEvent);

#if !defined(QT_NO_CONTEXTMENU) && defined(Q_WS_WINCE)

    if (!q->style()->styleHint(QStyle::SH_ScrollBar_ContextMenu, 0, q)) {

        q->setContextMenuPolicy(Qt::PreventContextMenu);

    }

#endif

}

#ifndef QT_NO_CONTEXTMENU

/*! \reimp */

void QScrollBar::contextMenuEvent(QContextMenuEvent *event)

{

    if (!style()->styleHint(QStyle::SH_ScrollBar_ContextMenu, 0, this)) {

        QAbstractSlider::contextMenuEvent(event);

        return ;

    }

#ifndef QT_NO_MENU

    bool horiz = HORIZONTAL;

    QPointer<QMenu> menu = new QMenu(this);

    QAction *actScrollHere = menu->addAction(tr("Scroll here"));

    menu->addSeparator();

    QAction *actScrollTop =  menu->addAction(horiz ? tr("Left edge") : tr("Top"));

    QAction *actScrollBottom = menu->addAction(horiz ? tr("Right edge") : tr("Bottom"));

    menu->addSeparator();

    QAction *actPageUp = menu->addAction(horiz ? tr("Page left") : tr("Page up"));

    QAction *actPageDn = menu->addAction(horiz ? tr("Page right") : tr("Page down"));

    menu->addSeparator();

    QAction *actScrollUp = menu->addAction(horiz ? tr("Scroll left") : tr("Scroll up"));

    QAction *actScrollDn = menu->addAction(horiz ? tr("Scroll right") : tr("Scroll down"));

    QAction *actionSelected = menu->exec(event->globalPos());

    delete menu;

    if (actionSelected == 0)

        /* do nothing */ ;

    else if (actionSelected == actScrollHere)

        setValue(d_func()->pixelPosToRangeValue(horiz ? event->pos().x() : event->pos().y()));

    else if (actionSelected == actScrollTop)

        triggerAction(QAbstractSlider::SliderToMinimum);

    else if (actionSelected == actScrollBottom)

        triggerAction(QAbstractSlider::SliderToMaximum);

    else if (actionSelected == actPageUp)

        triggerAction(QAbstractSlider::SliderPageStepSub);

    else if (actionSelected == actPageDn)

        triggerAction(QAbstractSlider::SliderPageStepAdd);

    else if (actionSelected == actScrollUp)

        triggerAction(QAbstractSlider::SliderSingleStepSub);

    else if (actionSelected == actScrollDn)

        triggerAction(QAbstractSlider::SliderSingleStepAdd);

#endif // QT_NO_MENU

}

#endif // QT_NO_CONTEXTMENU

/*! \reimp */

QSize QScrollBar::sizeHint() const

{

    ensurePolished();

    QStyleOptionSlider opt;

    initStyleOption(&opt);

    int scrollBarExtent = style()->pixelMetric(QStyle::PM_ScrollBarExtent, &opt, this);

    int scrollBarSliderMin = style()->pixelMetric(QStyle::PM_ScrollBarSliderMin, &opt, this);

    QSize size;

    if (opt.orientation == Qt::Horizontal)

        size = QSize(scrollBarExtent * 2 + scrollBarSliderMin, scrollBarExtent);

    else

        size = QSize(scrollBarExtent, scrollBarExtent * 2 + scrollBarSliderMin);

    return style()->sizeFromContents(QStyle::CT_ScrollBar, &opt, size, this)

        .expandedTo(QApplication::globalStrut());

 }

/*!\reimp */

void QScrollBar::sliderChange(SliderChange change)

{

    QAbstractSlider::sliderChange(change);

}

/*!

    \reimp

*/

bool QScrollBar::event(QEvent *event)

{

    switch(event->type()) {

    case QEvent::HoverEnter:

    case QEvent::HoverLeave:

    case QEvent::HoverMove:

    if (const QHoverEvent *he = static_cast<const QHoverEvent *>(event))

        d_func()->updateHoverControl(he->pos());

        break;

#ifndef QT_NO_WHEELEVENT

    case QEvent::Wheel: {

        // override wheel event without adding virtual function override

        QWheelEvent *ev = static_cast<QWheelEvent *>(event);