path: root/src/gui/util/qscrollerproperties.cpp

/****************************************************************************
**
** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtGui module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include <QPointer>
#include <QObject>
#include <QtCore/qmath.h>
#ifdef Q_WS_WIN
#  include <QLibrary>
#endif

#include "qscrollerproperties.h"
#include "private/qscrollerproperties_p.h"

QT_BEGIN_NAMESPACE

static QScrollerPropertiesPrivate *userDefaults = 0;
static QScrollerPropertiesPrivate *systemDefaults = 0;

QScrollerPropertiesPrivate *QScrollerPropertiesPrivate::defaults()
{
    if (!systemDefaults) {
        QScrollerPropertiesPrivate spp;
        spp.mousePressEventDelay = qreal(0.25);
        spp.dragStartDistance = qreal(5.0 / 1000);
        spp.dragVelocitySmoothingFactor = qreal(0.8);
        spp.axisLockThreshold = qreal(0);
        spp.scrollingCurve.setType(QEasingCurve::OutQuad);
        spp.decelerationFactor = qreal(0.125);
        spp.minimumVelocity = qreal(50.0 / 1000);
        spp.maximumVelocity = qreal(500.0 / 1000);
        spp.maximumClickThroughVelocity = qreal(66.5 / 1000);
        spp.acceleratingFlickMaximumTime = qreal(1.25);
        spp.acceleratingFlickSpeedupFactor = qreal(3.0);
        spp.snapPositionRatio = qreal(0.5);
        spp.snapTime = qreal(0.3);
        spp.overshootDragResistanceFactor = qreal(0.5);
        spp.overshootDragDistanceFactor = qreal(1);
        spp.overshootScrollDistanceFactor = qreal(0.5);
        spp.overshootScrollTime = qreal(0.7);
#  ifdef Q_WS_WIN
        if (QLibrary::resolve(QLatin1String("UxTheme"), "BeginPanningFeedback"))
            spp.overshootScrollTime = qreal(0.35);
#  endif
        spp.hOvershootPolicy = QScrollerProperties::OvershootWhenScrollable;
        spp.vOvershootPolicy = QScrollerProperties::OvershootWhenScrollable;
        spp.frameRate = QScrollerProperties::Standard;

        systemDefaults = new QScrollerPropertiesPrivate(spp);
    }
    return new QScrollerPropertiesPrivate(userDefaults ? *userDefaults : *systemDefaults);
}

/*!
    \class QScrollerProperties
    \brief The QScrollerProperties class stores the settings for a QScroller.
    \since 4.8

    The QScrollerProperties class stores the parameters used by QScroller.

    The default settings are platform dependant and Qt will emulate the
    platform behaviour for kinetic scrolling.

    As a convention the QScrollerProperties are in physical units (meter,
    seconds) and will be converted by QScroller using the current DPI.

    \sa QScroller
*/

/*!
    Constructs new scroller properties.
*/
QScrollerProperties::QScrollerProperties()
    : d(QScrollerPropertiesPrivate::defaults())
{
}

/*!
    Constructs a copy of \a sp.
*/
QScrollerProperties::QScrollerProperties(const QScrollerProperties &sp)
    : d(new QScrollerPropertiesPrivate(*sp.d))
{
}

/*!
    Assigns \a sp to these scroller properties and returns a reference to these scroller properties.
*/
QScrollerProperties &QScrollerProperties::operator=(const QScrollerProperties &sp)
{
    *d.data() = *sp.d.data();
    return *this;
}

/*!
    Destroys the scroller properties.
*/
QScrollerProperties::~QScrollerProperties()
{
}

/*!
    Returns true if these scroller properties are equal to \a sp; otherwise returns false.
*/
bool QScrollerProperties::operator==(const QScrollerProperties &sp) const
{
    return *d.data() == *sp.d.data();
}

/*!
    Returns true if these scroller properties are different from \a sp; otherwise returns false.
*/
bool QScrollerProperties::operator!=(const QScrollerProperties &sp) const
{
    return !(*d.data() == *sp.d.data());
}

bool QScrollerPropertiesPrivate::operator==(const QScrollerPropertiesPrivate &p) const
{
    bool same = true;
    same &= (mousePressEventDelay == p.mousePressEventDelay);
    same &= (dragStartDistance == p.dragStartDistance);
    same &= (dragVelocitySmoothingFactor == p.dragVelocitySmoothingFactor);
    same &= (axisLockThreshold == p.axisLockThreshold);
    same &= (scrollingCurve == p.scrollingCurve);
    same &= (decelerationFactor == p.decelerationFactor);
    same &= (minimumVelocity == p.minimumVelocity);
    same &= (maximumVelocity == p.maximumVelocity);
    same &= (maximumClickThroughVelocity == p.maximumClickThroughVelocity);
    same &= (acceleratingFlickMaximumTime == p.acceleratingFlickMaximumTime);
    same &= (acceleratingFlickSpeedupFactor == p.acceleratingFlickSpeedupFactor);
    same &= (snapPositionRatio == p.snapPositionRatio);
    same &= (snapTime == p.snapTime);
    same &= (overshootDragResistanceFactor == p.overshootDragResistanceFactor);
    same &= (overshootDragDistanceFactor == p.overshootDragDistanceFactor);
    same &= (overshootScrollDistanceFactor == p.overshootScrollDistanceFactor);
    same &= (overshootScrollTime == p.overshootScrollTime);
    same &= (hOvershootPolicy == p.hOvershootPolicy);
    same &= (vOvershootPolicy == p.vOvershootPolicy);
    same &= (frameRate == p.frameRate);
    return same;
}

/*!
     Sets the scroller properties returned by the default constructor to \a sp.

     Use this function to override the platform default properties returned by the default
     constructor. If you only want to change the scroller properties of a single scroller, then use
     QScroller::setScrollerProperties()

     \note Calling this function will not change the content of already existing
     QScrollerProperties objects.

     \sa unsetDefaultScrollerProperties()
*/
void QScrollerProperties::setDefaultScrollerProperties(const QScrollerProperties &sp)
{
    if (!userDefaults)
        userDefaults = new QScrollerPropertiesPrivate(*sp.d);
    else
        *userDefaults = *sp.d;
}

/*!
     Sets the scroller properties returned by the default constructor back to the platform default
     properties.

     \sa setDefaultScrollerProperties()
*/
void QScrollerProperties::unsetDefaultScrollerProperties()
{
    delete userDefaults;
    userDefaults = 0;
}

/*!
    Query the \a metric value of the scroller properties.

    \sa setScrollMetric(), ScrollMetric
*/
QVariant QScrollerProperties::scrollMetric(ScrollMetric metric) const
{
    switch (metric) {
    case MousePressEventDelay:          return d->mousePressEventDelay;
    case DragStartDistance:             return d->dragStartDistance;
    case DragVelocitySmoothingFactor:   return d->dragVelocitySmoothingFactor;
    case AxisLockThreshold:             return d->axisLockThreshold;
    case ScrollingCurve:                return d->scrollingCurve;
    case DecelerationFactor:            return d->decelerationFactor;
    case MinimumVelocity:               return d->minimumVelocity;
    case MaximumVelocity:               return d->maximumVelocity;
    case MaximumClickThroughVelocity:   return d->maximumClickThroughVelocity;
    case AcceleratingFlickMaximumTime:  return d->acceleratingFlickMaximumTime;
    case AcceleratingFlickSpeedupFactor:return d->acceleratingFlickSpeedupFactor;
    case SnapPositionRatio:             return d->snapPositionRatio;
    case SnapTime:                      return d->snapTime;
    case OvershootDragResistanceFactor: return d->overshootDragResistanceFactor;
    case OvershootDragDistanceFactor:   return d->overshootDragDistanceFactor;
    case OvershootScrollDistanceFactor: return d->overshootScrollDistanceFactor;
    case OvershootScrollTime:           return d->overshootScrollTime;
    case HorizontalOvershootPolicy:     return QVariant::fromValue(d->hOvershootPolicy);
    case VerticalOvershootPolicy:       return QVariant::fromValue(d->vOvershootPolicy);
    case FrameRate:                     return QVariant::fromValue(d->frameRate);
    case ScrollMetricCount:             break;
    }
    return QVariant();
}

/*!
    Set a specific value of the \a metric ScrollerMetric to \a value.

    \sa scrollMetric(), ScrollMetric
*/
void QScrollerProperties::setScrollMetric(ScrollMetric metric, const QVariant &value)
{
    switch (metric) {
    case MousePressEventDelay:          d->mousePressEventDelay = value.toReal(); break;
    case DragStartDistance:             d->dragStartDistance = value.toReal(); break;
    case DragVelocitySmoothingFactor:   d->dragVelocitySmoothingFactor = qBound(qreal(0), value.toReal(), qreal(1)); break;
    case AxisLockThreshold:             d->axisLockThreshold = qBound(qreal(0), value.toReal(), qreal(1)); break;
    case ScrollingCurve:                d->scrollingCurve = value.toEasingCurve(); break;
    case DecelerationFactor:            d->decelerationFactor = value.toReal(); break;
    case MinimumVelocity:               d->minimumVelocity = value.toReal(); break;
    case MaximumVelocity:               d->maximumVelocity = value.toReal(); break;
    case MaximumClickThroughVelocity:   d->maximumClickThroughVelocity = value.toReal(); break;
    case AcceleratingFlickMaximumTime:  d->acceleratingFlickMaximumTime = value.toReal(); break;
    case AcceleratingFlickSpeedupFactor:d->acceleratingFlickSpeedupFactor = value.toReal(); break;
    case SnapPositionRatio:             d->snapPositionRatio = qBound(qreal(0), value.toReal(), qreal(1)); break;
    case SnapTime:                      d->snapTime = value.toReal(); break;
    case OvershootDragResistanceFactor: d->overshootDragResistanceFactor = value.toReal(); break;
    case OvershootDragDistanceFactor:   d->overshootDragDistanceFactor = qBound(qreal(0), value.toReal(), qreal(1)); break;
    case OvershootScrollDistanceFactor: d->overshootScrollDistanceFactor = qBound(qreal(0), value.toReal(), qreal(1)); break;
    case OvershootScrollTime:           d->overshootScrollTime = value.toReal(); break;
    case HorizontalOvershootPolicy:     d->hOvershootPolicy = value.value<QScrollerProperties::OvershootPolicy>(); break;
    case VerticalOvershootPolicy:       d->vOvershootPolicy = value.value<QScrollerProperties::OvershootPolicy>(); break;
    case FrameRate:                     d->frameRate = value.value<QScrollerProperties::FrameRates>(); break;
    case ScrollMetricCount:             break;
    }
}

/*!
    \enum QScrollerProperties::FrameRates

    This enum describes the available frame rates used while dragging or scrolling.

    \value Fps60 60 frames per second
    \value Fps30 30 frames per second
    \value Fps20 20 frames per second
    \value Standard the default value is 60 frames per second (which corresponds to QAbstractAnimation).
*/

/*!
    \enum QScrollerProperties::OvershootPolicy

    This enum describes the various modes of overshooting.

    \value OvershootWhenScrollable Overshooting is when the content is scrollable. This is the
                                   default.

    \value OvershootAlwaysOff Overshooting is never enabled (even when the content is scrollable).

    \value OvershootAlwaysOn Overshooting is always enabled (even when the content is not
                             scrollable).
*/

/*!
    \enum QScrollerProperties::ScrollMetric

    This enum contains the different scroll metric types. When not indicated otherwise the
    setScrollMetric function expects a QVariant of a real value.

    See the QScroller documentation for a further explanation of the concepts behind the different
    values.

    \value MousePressEventDelay This is the time a mouse press event will be delayed when starting
    a flick gesture in \c{[s]}. If the gesture is triggered within that time, no mouse press or
    release will be sent to the scrolled object. If it triggers after that delay the (delayed)
    mouse press plus a faked release event (at global postion \c{QPoint(-QWIDGETSIZE_MAX,
    -QWIDGETSIZE_MAX)} will be sent. If the gesture is canceled, then both the (delayed) mouse
    press plus the real release event will be delivered.

    \value DragStartDistance This is the minimum distance the touch or mouse point needs to be
    moved before the flick gesture is triggered in \c m.

    \value DragVelocitySmoothingFactor A value that describes how much new drag velocities are
    included in the final scrolling velocity.  This value should be in the range between \c 0 and
    \c 1.  The lower the value, the more smoothing will be applied to the dragging velocity.  The
    default value is \c 0.8.

    \value AxisLockThreshold If greater than zero a scroll movement will be restricted to one axis
    only if the movement is inside an angle about the axis. The threshold must be in the range \c 0
    to \c 1.

    \value ScrollingCurve The QEasingCurve used when decelerating the scrolling velocity after an
    user initiated flick. Please note that this is the easing curve for the positions, \bold{not}
    the velocity: the default is QEasingCurve::OutQuad, which results is a linear decrease in
    velocity (1st derivative) and a constant deceleration (2nd derivative).

    \value DecelerationFactor This factor influences how long it takes the scroller to decelerate
    to 0 velocity. The actual value heavily depends on the chosen ScrollingCurve, but for most
    types the value should be in the range from \c 0.1 to \c 2.0

    \value MinimumVelocity The minimum velocity that is needed after ending the touch or releasing
    the mouse to start scrolling in \c{m/s}.

    \value MaximumVelocity This is the maximum velocity that can be reached in \c{m/s}.

    \value MaximumClickThroughVelocity This is the maximum allowed scroll speed for a click-through
    in \c{m/s}. This means that a click on a currently (slowly) scrolling object will not only stop
    the scrolling but the click event will also be delivered to the UI control - this is very
    useful when using exponential-type scrolling curves.

    \value AcceleratingFlickMaximumTime This is the maximum time in \c seconds that a flick gesture
    can take to be recognized as an accelerating flick. If set to zero no such gesture will be
    detected. An "accelerating flick" is a flick gesture executed on an already scrolling object.
    In such cases the scrolling speed is multiplied by AcceleratingFlickSpeedupFactor in order to
    accelerate it.

    \value AcceleratingFlickSpeedupFactor The current speed will be multiplied by this number if an
    accelerating flick is detected. Should be \c{> 1}.

    \value SnapPositionRatio This is the distance that the user must drag the area beween two snap
    points in order to snap it to the next position. e.g. \c{0.33} means that the scroll must only
    reach one third of the distance between two snap points to snap to the next one. The ratio must
    be in the range \c 0 to \c 1.

    \value SnapTime This is the time factor for the scrolling curve. A lower value means that the
    scrolling will take longer. The scrolling distance is independet of this value.

    \value OvershootDragResistanceFactor This value is the factor between the mouse dragging and
    the actual scroll area movement (during overshoot). The factor must be in the range \c 0 to \c
    1.

    \value OvershootDragDistanceFactor This is the maximum distance for overshoot movements while
    dragging. The actual overshoot distance will be calculated by multiplying this value with the
    viewport size of the scrolled object. The factor must be in the range \c 0 to \c 1.

    \value OvershootScrollDistanceFactor This is the maximum distance for overshoot movements while
    scrolling. The actual overshoot distance will be calculated by multiplying this value with the
    viewport size of the scrolled object. The factor must be in the range \c 0 to \c 1.

    \value OvershootScrollTime This is the time in \c seconds that will be used to play the
    complete overshoot animation.

    \value HorizontalOvershootPolicy This is the horizontal overshooting policy (see OvershootPolicy).

    \value VerticalOvershootPolicy This is the horizontal overshooting policy (see OvershootPolicy).

    \value FrameRate This is the frame rate which should be used while dragging or scrolling.
    QScroller uses a QAbstractAnimation timer internally to sync all scrolling operations to other
    animations that might be active at the same time.  If the Standard value of 60 frames per
    second is too fast for your use case, you can lower the frames per second with this setting
    (while still being in-sync with QAbstractAnimation).  Please note that only the values of the
    FrameRates enum are allowed here.

    \value ScrollMetricCount This is just used when enumerating the metrics. It is always the last
    entry.
*/

QT_END_NAMESPACE