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**
** Copyright (C) 2016 The Qt Company Ltd.
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****************************************************************************/

#include "qquickslider_p.h"
#include "qquickcontrol_p_p.h"

#include <QtQuick/private/qquickwindow_p.h>

QT_BEGIN_NAMESPACE

/*!
    \qmltype Slider
    \inherits Control
    \instantiates QQuickSlider
    \inqmlmodule QtQuick.Controls
    \since 5.7
    \ingroup qtquickcontrols2-input
    \brief Selects a value by sliding a handle along a track.

    \image qtquickcontrols2-slider.gif

    Slider is used to select a value by sliding a handle along a track.

    \table
    \row \li \image qtquickcontrols2-slider-normal.png
         \li A slider in its normal state.
    \row \li \image qtquickcontrols2-slider-focused.png
         \li A slider that has active focus.
    \row \li \image qtquickcontrols2-slider-disabled.png
         \li A slider that is disabled.
    \endtable

    \code
    Slider {
        value: 0.5
    }
    \endcode

    \sa {Customizing Slider}, {Input Controls}
*/

class QQuickSliderPrivate : public QQuickControlPrivate
{
    Q_DECLARE_PUBLIC(QQuickSlider)

public:
    QQuickSliderPrivate() : from(0), to(1), value(0), position(0), stepSize(0), pressed(false),
        orientation(Qt::Horizontal), snapMode(QQuickSlider::NoSnap),
        handle(nullptr)
    {
    }

    qreal valueAt(qreal position) const;
    qreal snapPosition(qreal position) const;
    qreal positionAt(const QPoint &point) const;
    void setPosition(qreal position);
    void updatePosition();

    qreal from;
    qreal to;
    qreal value;
    qreal position;
    qreal stepSize;
    bool pressed;
    QPoint pressPoint;
    Qt::Orientation orientation;
    QQuickSlider::SnapMode snapMode;
    QQuickItem *handle;
};

qreal QQuickSliderPrivate::valueAt(qreal position) const
{
    return from + (to - from) * position;
}

qreal QQuickSliderPrivate::snapPosition(qreal position) const
{
    const qreal range = to - from;
    if (qFuzzyIsNull(range))
        return position;

    const qreal effectiveStep = stepSize / range;
    if (qFuzzyIsNull(effectiveStep))
        return position;

    return qRound(position / effectiveStep) * effectiveStep;
}

qreal QQuickSliderPrivate::positionAt(const QPoint &point) const
{
    Q_Q(const QQuickSlider);
    if (orientation == Qt::Horizontal) {
        const qreal hw = handle ? handle->width() : 0;
        const qreal offset = hw / 2;
        const qreal extent = q->availableWidth() - hw;
        if (!qFuzzyIsNull(extent)) {
            if (q->isMirrored())
                return (q->width() - point.x() - q->rightPadding() - offset) / extent;
            return (point.x() - q->leftPadding() - offset) / extent;
        }
    } else {
        const qreal hh = handle ? handle->height() : 0;
        const qreal offset = hh / 2;
        const qreal extent = q->availableHeight() - hh;
        if (!qFuzzyIsNull(extent))
            return (q->height() - point.y() - q->bottomPadding() - offset) / extent;
    }
    return 0;
}

void QQuickSliderPrivate::setPosition(qreal pos)
{
    Q_Q(QQuickSlider);
    pos = qBound<qreal>(0.0, pos, 1.0);
    if (qFuzzyCompare(position, pos))
        return;

    position = pos;
    emit q->positionChanged();
    emit q->visualPositionChanged();
}

void QQuickSliderPrivate::updatePosition()
{
    qreal pos = 0;
    if (!qFuzzyCompare(from, to))
        pos = (value - from) / (to - from);
    setPosition(pos);
}

QQuickSlider::QQuickSlider(QQuickItem *parent) :
    QQuickControl(*(new QQuickSliderPrivate), parent)
{
    setActiveFocusOnTab(true);
    setFocusPolicy(Qt::StrongFocus);
    setAcceptedMouseButtons(Qt::LeftButton);
}

/*!
    \qmlproperty real QtQuick.Controls::Slider::from

    This property holds the starting value for the range. The default value is \c 0.0.

    \sa to, value
*/
qreal QQuickSlider::from() const
{
    Q_D(const QQuickSlider);
    return d->from;
}

void QQuickSlider::setFrom(qreal from)
{
    Q_D(QQuickSlider);
    if (qFuzzyCompare(d->from, from))
        return;

    d->from = from;
    emit fromChanged();
    if (isComponentComplete()) {
        setValue(d->value);
        d->updatePosition();
    }
}

/*!
    \qmlproperty real QtQuick.Controls::Slider::to

    This property holds the end value for the range. The default value is \c 1.0.

    \sa from, value
*/
qreal QQuickSlider::to() const
{
    Q_D(const QQuickSlider);
    return d->to;
}

void QQuickSlider::setTo(qreal to)
{
    Q_D(QQuickSlider);
    if (qFuzzyCompare(d->to, to))
        return;

    d->to = to;
    emit toChanged();
    if (isComponentComplete()) {
        setValue(d->value);
        d->updatePosition();
    }
}

/*!
    \qmlproperty real QtQuick.Controls::Slider::value

    This property holds the value in the range \c from - \c to. The default value is \c 0.0.

    Unlike the \l position property, the \c value is not updated while the
    handle is dragged. The value is updated after the value has been chosen
    and the slider has been released.

    \sa position
*/
qreal QQuickSlider::value() const
{
    Q_D(const QQuickSlider);
    return d->value;
}

void QQuickSlider::setValue(qreal value)
{
    Q_D(QQuickSlider);
    if (isComponentComplete())
        value = d->from > d->to ? qBound(d->to, value, d->from) : qBound(d->from, value, d->to);

    if (qFuzzyCompare(d->value, value))
        return;

    d->value = value;
    d->updatePosition();
    emit valueChanged();
}

/*!
    \qmlproperty real QtQuick.Controls::Slider::position
    \readonly

    This property holds the logical position of the handle.

    The position is defined as a percentage of the control's size, scaled
    to \c {0.0 - 1.0}. Unlike the \l value property, the \c position is
    continuously updated while the handle is dragged. For visualizing a
    slider, the right-to-left aware \l visualPosition should be used instead.

    \sa value, visualPosition
*/
qreal QQuickSlider::position() const
{
    Q_D(const QQuickSlider);
    return d->position;
}

/*!
    \qmlproperty real QtQuick.Controls::Slider::visualPosition
    \readonly

    This property holds the visual position of the handle.

    The position is defined as a percentage of the control's size, scaled to
    \c {0.0 - 1.0}. When the control is \l {Control::mirrored}{mirrored}, the
    value is equal to \c {1.0 - position}. This makes the value suitable for
    visualizing the slider, taking right-to-left support into account.

    \sa position
*/
qreal QQuickSlider::visualPosition() const
{
    Q_D(const QQuickSlider);
    if (d->orientation == Qt::Vertical || isMirrored())
        return 1.0 - d->position;
    return d->position;
}

/*!
    \qmlproperty real QtQuick.Controls::Slider::stepSize

    This property holds the step size. The default value is \c 0.0.

    \sa snapMode, increase(), decrease()
*/
qreal QQuickSlider::stepSize() const
{
    Q_D(const QQuickSlider);
    return d->stepSize;
}

void QQuickSlider::setStepSize(qreal step)
{
    Q_D(QQuickSlider);
    if (qFuzzyCompare(d->stepSize, step))
        return;

    d->stepSize = step;
    emit stepSizeChanged();
}

/*!
    \qmlproperty enumeration QtQuick.Controls::Slider::snapMode

    This property holds the snap mode.

    Possible values:
    \value Slider.NoSnap The slider does not snap (default).
    \value Slider.SnapAlways The slider snaps while the handle is dragged.
    \value Slider.SnapOnRelease The slider does not snap while being dragged, but only after the handle is released.

    \sa stepSize
*/
QQuickSlider::SnapMode QQuickSlider::snapMode() const
{
    Q_D(const QQuickSlider);
    return d->snapMode;
}

void QQuickSlider::setSnapMode(SnapMode mode)
{
    Q_D(QQuickSlider);
    if (d->snapMode == mode)
        return;

    d->snapMode = mode;
    emit snapModeChanged();
}

/*!
    \qmlproperty bool QtQuick.Controls::Slider::pressed

    This property holds whether the slider is pressed.
*/
bool QQuickSlider::isPressed() const
{
    Q_D(const QQuickSlider);
    return d->pressed;
}

void QQuickSlider::setPressed(bool pressed)
{
    Q_D(QQuickSlider);
    if (d->pressed == pressed)
        return;

    d->pressed = pressed;
    setAccessibleProperty("pressed", pressed);
    emit pressedChanged();
}

/*!
    \qmlproperty enumeration QtQuick.Controls::Slider::orientation

    This property holds the orientation.

    Possible values:
    \value Qt.Horizontal Horizontal (default)
    \value Qt.Vertical Vertical
*/
Qt::Orientation QQuickSlider::orientation() const
{
    Q_D(const QQuickSlider);
    return d->orientation;
}

void QQuickSlider::setOrientation(Qt::Orientation orientation)
{
    Q_D(QQuickSlider);
    if (d->orientation == orientation)
        return;

    d->orientation = orientation;
    emit orientationChanged();
}

/*!
    \qmlproperty Item QtQuick.Controls::Slider::handle

    This property holds the handle item.

    \sa {Customizing Slider}
*/
QQuickItem *QQuickSlider::handle() const
{
    Q_D(const QQuickSlider);
    return d->handle;
}

void QQuickSlider::setHandle(QQuickItem *handle)
{
    Q_D(QQuickSlider);
    if (d->handle == handle)
        return;

    d->deleteDelegate(d->handle);
    d->handle = handle;
    if (handle && !handle->parentItem())
        handle->setParentItem(this);
    emit handleChanged();
}

/*!
    \qmlmethod void QtQuick.Controls::Slider::increase()

    Increases the value by \l stepSize or \c 0.1 if stepSize is not defined.

    \sa stepSize
*/
void QQuickSlider::increase()
{
    Q_D(QQuickSlider);
    qreal step = qFuzzyIsNull(d->stepSize) ? 0.1 : d->stepSize;
    setValue(d->value + step);
}

/*!
    \qmlmethod void QtQuick.Controls::Slider::decrease()

    Decreases the value by \l stepSize or \c 0.1 if stepSize is not defined.

    \sa stepSize
*/
void QQuickSlider::decrease()
{
    Q_D(QQuickSlider);
    qreal step = qFuzzyIsNull(d->stepSize) ? 0.1 : d->stepSize;
    setValue(d->value - step);
}

void QQuickSlider::keyPressEvent(QKeyEvent *event)
{
    Q_D(QQuickSlider);
    QQuickControl::keyPressEvent(event);
    if (d->orientation == Qt::Horizontal) {
        if (event->key() == Qt::Key_Left) {
            setPressed(true);
            if (isMirrored())
                increase();
            else
                decrease();
            event->accept();
        } else if (event->key() == Qt::Key_Right) {
            setPressed(true);
            if (isMirrored())
                decrease();
            else
                increase();
            event->accept();
        }
    } else {
        if (event->key() == Qt::Key_Up) {
            setPressed(true);
            increase();
            event->accept();
        } else if (event->key() == Qt::Key_Down) {
            setPressed(true);
            decrease();
            event->accept();
        }
    }
}

void QQuickSlider::keyReleaseEvent(QKeyEvent *event)
{
    QQuickControl::keyReleaseEvent(event);
    setPressed(false);
}

void QQuickSlider::mousePressEvent(QMouseEvent *event)
{
    Q_D(QQuickSlider);
    QQuickControl::mousePressEvent(event);
    d->pressPoint = event->pos();
    setPressed(true);
}

void QQuickSlider::mouseMoveEvent(QMouseEvent *event)
{
    Q_D(QQuickSlider);
    QQuickControl::mouseMoveEvent(event);
    if (!keepMouseGrab()) {
        if (d->orientation == Qt::Horizontal)
            setKeepMouseGrab(QQuickWindowPrivate::dragOverThreshold(event->pos().x() - d->pressPoint.x(), Qt::XAxis, event));
        else
            setKeepMouseGrab(QQuickWindowPrivate::dragOverThreshold(event->pos().y() - d->pressPoint.y(), Qt::YAxis, event));
    }
    if (keepMouseGrab()) {
        qreal pos = d->positionAt(event->pos());
        if (d->snapMode == SnapAlways)
            pos = d->snapPosition(pos);
        d->setPosition(pos);
    }
}

void QQuickSlider::mouseReleaseEvent(QMouseEvent *event)
{
    Q_D(QQuickSlider);
    QQuickControl::mouseReleaseEvent(event);
    d->pressPoint = QPoint();
    qreal pos = d->positionAt(event->pos());
    if (d->snapMode != NoSnap)
        pos = d->snapPosition(pos);
    qreal val = d->valueAt(pos);
    if (!qFuzzyCompare(val, d->value))
        setValue(val);
    else if (d->snapMode != NoSnap)
        d->setPosition(pos);
    setKeepMouseGrab(false);
    setPressed(false);
}

void QQuickSlider::mouseUngrabEvent()
{
    Q_D(QQuickSlider);
    QQuickControl::mouseUngrabEvent();
    d->pressPoint = QPoint();
    setPressed(false);
}

void QQuickSlider::wheelEvent(QWheelEvent *event)
{
    Q_D(QQuickSlider);
    QQuickControl::wheelEvent(event);
    if (d->wheelEnabled) {
        const qreal oldValue = d->value;
        const QPointF angle = event->angleDelta();
        const qreal delta = (qFuzzyIsNull(angle.y()) ? angle.x() : angle.y()) / QWheelEvent::DefaultDeltasPerStep;
        const qreal step = qFuzzyIsNull(d->stepSize) ? 0.1 : d->stepSize;
        setValue(oldValue + step * delta);
        event->setAccepted(!qFuzzyCompare(d->value, oldValue));
    }
}

void QQuickSlider::mirrorChange()
{
    QQuickControl::mirrorChange();
    emit visualPositionChanged();
}

void QQuickSlider::componentComplete()
{
    Q_D(QQuickSlider);
    QQuickControl::componentComplete();
    setValue(d->value);
    d->updatePosition();
}

#ifndef QT_NO_ACCESSIBILITY
void QQuickSlider::accessibilityActiveChanged(bool active)
{
    QQuickControl::accessibilityActiveChanged(active);

    Q_D(QQuickSlider);
    if (active)
        setAccessibleProperty("pressed", d->pressed);
}

QAccessible::Role QQuickSlider::accessibleRole() const
{
    return QAccessible::Slider;
}
#endif

QT_END_NAMESPACE
