Qt.labs.animation: Make plugin optional

This moves the animation types into a new library and is meant to make
them availabe to the QML compiler at some point in the future.

Task-number: QTBUG-90487
Change-Id: I19bd864253941931706933f7e517bb31938e9cc2
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

5 files changed, 822 insertions, 0 deletions

diff --git a/src/labs/CMakeLists.txt b/src/labs/CMakeLists.txt
index 5dc715db60..de832a1db2 100644
--- a/src/labs/CMakeLists.txt
+++ b/src/labs/CMakeLists.txt
@@ -1,4 +1,9 @@
 add_subdirectory(settings)
+
 if(QT_FEATURE_qml_itemmodel)
     add_subdirectory(folderlistmodel)
 endif()
+
+if(TARGET Qt::Quick)
+    add_subdirectory(animation)
+endif()
diff --git a/src/labs/animation/CMakeLists.txt b/src/labs/animation/CMakeLists.txt
new file mode 100644
index 0000000000..77b8ab7fec
--- /dev/null
+++ b/src/labs/animation/CMakeLists.txt
@@ -0,0 +1,21 @@
+qt_internal_add_module(LabsAnimation
+  GENERATE_METATYPES
+  SOURCES
+      qquickboundaryrule.cpp qquickboundaryrule_p.h
+      qqmlanimationglobal_p.h
+  DEFINES
+      QT_BUILD_LABSANIMATION_LIB
+  PUBLIC_LIBRARIES
+      Qt::QmlPrivate
+      Qt::QuickPrivate
+)
+
+set_target_properties(LabsAnimation PROPERTIES
+    QT_QML_MODULE_INSTALL_QMLTYPES TRUE
+    QT_QML_MODULE_VERSION ${CMAKE_PROJECT_VERSION}
+    QT_QML_MODULE_URI Qt.labs.animation
+    QT_QMLTYPES_FILENAME plugins.qmltypes
+    QT_QML_MODULE_INSTALL_DIR "${INSTALL_QMLDIR}/Qt/labs/animation"
+)
+
+qt6_qml_type_registration(LabsAnimation)
diff --git a/src/labs/animation/qqmlanimationglobal_p.h b/src/labs/animation/qqmlanimationglobal_p.h
new file mode 100644
index 0000000000..9ba3ecea2a
--- /dev/null
+++ b/src/labs/animation/qqmlanimationglobal_p.h
@@ -0,0 +1,73 @@
+/****************************************************************************
+**
+** Copyright (C) 2021 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQml module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QTLABSANIMATIONGLOBAL_P_H
+#define QTLABSANIMATIONGLOBAL_P_H
+
+#include <QtCore/qglobal.h>
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+QT_BEGIN_NAMESPACE
+
+#if !defined(QT_STATIC)
+#  if defined(QT_BUILD_LABSANIMATION_LIB)
+#    define Q_LABSANIMATION_EXPORT Q_DECL_EXPORT
+#  else
+#    define Q_LABSANIMATION_EXPORT Q_DECL_IMPORT
+#  endif
+#else
+#  define Q_LABSANIMATION_EXPORT
+#endif
+#define Q_LABSANIMATION_PRIVATE_EXPORT Q_LABSANIMATION_EXPORT
+
+QT_END_NAMESPACE
+
+void Q_LABSANIMATION_PRIVATE_EXPORT qml_register_types_Qt_labs_animation();
+
+#endif // QTLABSANIMATIONGLOBAL_P_H
diff --git a/src/labs/animation/qquickboundaryrule.cpp b/src/labs/animation/qquickboundaryrule.cpp
new file mode 100644
index 0000000000..3083dd26d2
--- /dev/null
+++ b/src/labs/animation/qquickboundaryrule.cpp
@@ -0,0 +1,574 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQuick module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qquickboundaryrule_p.h"
+
+#include <qqmlcontext.h>
+#include <qqmlinfo.h>
+#include <private/qqmlproperty_p.h>
+#include <private/qqmlengine_p.h>
+#include <private/qobject_p.h>
+#include <private/qquickanimation_p_p.h>
+#include <QtCore/qloggingcategory.h>
+
+QT_BEGIN_NAMESPACE
+
+Q_LOGGING_CATEGORY(lcBR, "qt.quick.boundaryrule")
+
+class QQuickBoundaryReturnJob;
+class QQuickBoundaryRulePrivate : public QObjectPrivate
+{
+    Q_DECLARE_PUBLIC(QQuickBoundaryRule)
+public:
+    QQuickBoundaryRulePrivate() {}
+
+    QQmlProperty property;
+    QEasingCurve easing = QEasingCurve(QEasingCurve::OutQuad);
+    QQuickBoundaryReturnJob *returnAnimationJob = nullptr;
+    // read-only properties, updated on each write()
+    qreal targetValue = 0; // after easing was applied
+    qreal peakOvershoot = 0;
+    qreal currentOvershoot = 0;
+    // settable properties
+    qreal minimum = 0;
+    qreal maximum = 0;
+    qreal minimumOvershoot = 0;
+    qreal maximumOvershoot = 0;
+    qreal overshootScale = 0.5;
+    int returnDuration = 100;
+    QQuickBoundaryRule::OvershootFilter overshootFilter = QQuickBoundaryRule::OvershootFilter::None;
+    bool enabled = true;
+    bool finalized = false;
+
+    qreal easedOvershoot(qreal overshootingValue);
+    void resetOvershoot();
+};
+
+class QQuickBoundaryReturnJob : public QAbstractAnimationJob
+{
+public:
+    QQuickBoundaryReturnJob(QQuickBoundaryRulePrivate *br, qreal to)
+        : QAbstractAnimationJob()
+        , boundaryRule(br)
+        , fromValue(br->targetValue)
+        , toValue(to) {}
+
+    int duration() const override { return boundaryRule->returnDuration; }
+
+    void updateCurrentTime(int) override;
+
+    void updateState(QAbstractAnimationJob::State newState,
+                     QAbstractAnimationJob::State oldState) override;
+
+    QQuickBoundaryRulePrivate *boundaryRule;
+    qreal fromValue;    // snapshot of initial value from which we're returning
+    qreal toValue;      // target property value to which we're returning
+};
+
+void QQuickBoundaryReturnJob::updateCurrentTime(int t)
+{
+    // The easing property tells how to behave when the property is being
+    // externally manipulated beyond the bounds.  During returnToBounds()
+    // we run it in reverse, by reversing time.
+    qreal progress = (duration() - t) / qreal(duration());
+    qreal easingValue = boundaryRule->easing.valueForProgress(progress);
+    qreal delta = qAbs(fromValue - toValue) * easingValue;
+    qreal value = (fromValue > toValue ? toValue + delta : toValue - delta);
+    qCDebug(lcBR) << t << "ms" << qRound(progress * 100) << "% easing" << easingValue << "->" << value;
+    QQmlPropertyPrivate::write(boundaryRule->property, value,
+                               QQmlPropertyData::BypassInterceptor | QQmlPropertyData::DontRemoveBinding);
+}
+
+void QQuickBoundaryReturnJob::updateState(QAbstractAnimationJob::State newState, QAbstractAnimationJob::State oldState)
+{
+    Q_UNUSED(oldState);
+    if (newState == QAbstractAnimationJob::Stopped) {
+        qCDebug(lcBR) << "return animation done";
+        boundaryRule->resetOvershoot();
+        boundaryRule->returnAnimationJob = nullptr;
+        delete this;
+    }
+}
+
+/*!
+    \qmltype BoundaryRule
+    \instantiates QQuickBoundaryRule
+    \inqmlmodule Qt.labs.animation
+    \ingroup qtquick-transitions-animations
+    \ingroup qtquick-interceptors
+    \brief Defines a restriction on the range of values that can be set on a numeric property.
+    \since 5.14
+
+    A BoundaryRule defines the range of values that a particular property is
+    allowed to have.  When an out-of-range value would otherwise be set,
+    it applies "resistance" via an easing curve.
+
+    For example, the following BoundaryRule prevents DragHandler from dragging
+    the Rectangle too far:
+
+    \snippet qml/boundaryRule.qml 0
+
+    Note that a property cannot have more than one assigned BoundaryRule.
+
+    \sa {Animation and Transitions in Qt Quick}, {Qt Quick Examples - Animation#Behaviors}{Behavior example}, {Qt QML}
+*/
+
+QQuickBoundaryRule::QQuickBoundaryRule(QObject *parent)
+    : QObject(*(new QQuickBoundaryRulePrivate), parent)
+    , QQmlPropertyValueInterceptor()
+{
+}
+
+QQuickBoundaryRule::~QQuickBoundaryRule()
+{
+    Q_D(QQuickBoundaryRule);
+    // stop any running animation and
+    // prevent QQuickBoundaryReturnJob::updateState() from accessing QQuickBoundaryRulePrivate
+    delete d->returnAnimationJob;
+}
+
+/*!
+    \qmlproperty bool QtQuick::BoundaryRule::enabled
+
+    This property holds whether the rule will be enforced when the tracked
+    property changes value.
+
+    By default a BoundaryRule is enabled.
+*/
+bool QQuickBoundaryRule::enabled() const
+{
+    Q_D(const QQuickBoundaryRule);
+    return d->enabled;
+}
+
+void QQuickBoundaryRule::setEnabled(bool enabled)
+{
+    Q_D(QQuickBoundaryRule);
+    if (d->enabled == enabled)
+        return;
+    d->enabled = enabled;
+    emit enabledChanged();
+}
+
+/*!
+    \qmlproperty qreal QtQuick::BoundaryRule::minimum
+
+    This property holds the smallest unconstrained value that the property is
+    allowed to have.  If the property is set to a smaller value, it will be
+    constrained by \l easing and \l minimumOvershoot.
+
+    The default is \c 0.
+*/
+qreal QQuickBoundaryRule::minimum() const
+{
+    Q_D(const QQuickBoundaryRule);
+    return d->minimum;
+}
+
+void QQuickBoundaryRule::setMinimum(qreal minimum)
+{
+    Q_D(QQuickBoundaryRule);
+    if (qFuzzyCompare(d->minimum, minimum))
+        return;
+    d->minimum = minimum;
+    emit minimumChanged();
+}
+
+/*!
+    \qmlproperty qreal QtQuick::BoundaryRule::minimumOvershoot
+
+    This property holds the amount that the property is allowed to be
+    less than \l minimum.  Whenever the value is less than \l minimum
+    and greater than \c {minimum - minimumOvershoot}, it is constrained
+    by the \l easing curve.  When the value attempts to go under
+    \c {minimum - minimumOvershoots} there is a hard stop.
+
+    The default is \c 0.
+*/
+qreal QQuickBoundaryRule::minimumOvershoot() const
+{
+    Q_D(const QQuickBoundaryRule);
+    return d->minimumOvershoot;
+}
+
+void QQuickBoundaryRule::setMinimumOvershoot(qreal minimumOvershoot)
+{
+    Q_D(QQuickBoundaryRule);
+    if (qFuzzyCompare(d->minimumOvershoot, minimumOvershoot))
+        return;
+    d->minimumOvershoot = minimumOvershoot;
+    emit minimumOvershootChanged();
+}
+
+/*!
+    \qmlproperty qreal QtQuick::BoundaryRule::maximum
+
+    This property holds the largest unconstrained value that the property is
+    allowed to have.  If the property is set to a larger value, it will be
+    constrained by \l easing and \l maximumOvershoot.
+
+    The default is \c 1.
+*/
+qreal QQuickBoundaryRule::maximum() const
+{
+    Q_D(const QQuickBoundaryRule);
+    return d->maximum;
+}
+
+void QQuickBoundaryRule::setMaximum(qreal maximum)
+{
+    Q_D(QQuickBoundaryRule);
+    if (qFuzzyCompare(d->maximum, maximum))
+        return;
+    d->maximum = maximum;
+    emit maximumChanged();
+}
+
+/*!
+    \qmlproperty qreal QtQuick::BoundaryRule::maximumOvershoot
+
+    This property holds the amount that the property is allowed to be
+    more than \l maximum.  Whenever the value is greater than \l maximum
+    and less than \c {maximum + maximumOvershoot}, it is constrained
+    by the \l easing curve.  When the value attempts to exceed
+    \c {maximum + maximumOvershoot} there is a hard stop.
+
+    The default is 0.
+*/
+qreal QQuickBoundaryRule::maximumOvershoot() const
+{
+    Q_D(const QQuickBoundaryRule);
+    return d->maximumOvershoot;
+}
+
+void QQuickBoundaryRule::setMaximumOvershoot(qreal maximumOvershoot)
+{
+    Q_D(QQuickBoundaryRule);
+    if (qFuzzyCompare(d->maximumOvershoot, maximumOvershoot))
+        return;
+    d->maximumOvershoot = maximumOvershoot;
+    emit maximumOvershootChanged();
+}
+
+/*!
+    \qmlproperty qreal QtQuick::BoundaryRule::overshootScale
+
+    This property holds the amount by which the \l easing is scaled during the
+    overshoot condition. For example if an Item is restricted from moving more
+    than 100 pixels beyond some limit, and the user (by means of some Input
+    Handler) is trying to drag it 100 pixels past the limit, if overshootScale
+    is set to 1, the user will succeed: the only effect of the easing curve is
+    to change the rate at which the item moves from overshoot 0 to overshoot
+    100. But if it is set to 0.5, the BoundaryRule provides resistance such
+    that when the user tries to move 100 pixels, the Item will only move 50
+    pixels; and the easing curve modulates the rate of movement such that it
+    may move in sync with the user's attempted movement at the beginning, and
+    then slows down, depending on the shape of the easing curve.
+
+    The default is 0.5.
+*/
+qreal QQuickBoundaryRule::overshootScale() const
+{
+    Q_D(const QQuickBoundaryRule);
+    return d->overshootScale;
+}
+
+void QQuickBoundaryRule::setOvershootScale(qreal overshootScale)
+{
+    Q_D(QQuickBoundaryRule);
+    if (qFuzzyCompare(d->overshootScale, overshootScale))
+        return;
+    d->overshootScale = overshootScale;
+    emit overshootScaleChanged();
+}
+
+/*!
+    \qmlproperty qreal QtQuick::BoundaryRule::currentOvershoot
+
+    This property holds the amount by which the most recently set value of the
+    intercepted property exceeds \l maximum or is less than \l minimum.
+
+    It is positive if the property value exceeds \l maximum, negative if the
+    property value is less than \l minimum, or 0 if the property value is
+    within both boundaries.
+*/
+qreal QQuickBoundaryRule::currentOvershoot() const
+{
+    Q_D(const QQuickBoundaryRule);
+    return d->currentOvershoot;
+}
+
+/*!
+    \qmlproperty qreal QtQuick::BoundaryRule::peakOvershoot
+
+    This property holds the most-positive or most-negative value of
+    \l currentOvershoot that has been seen, until \l returnToBounds() is called.
+
+    This can be useful when the intercepted property value is known to
+    fluctuate, and you want to find and react to the maximum amount of
+    overshoot rather than to the fluctuations.
+
+    \sa overshootFilter
+*/
+qreal QQuickBoundaryRule::peakOvershoot() const
+{
+    Q_D(const QQuickBoundaryRule);
+    return d->peakOvershoot;
+}
+
+/*!
+    \qmlproperty enum QtQuick::BoundaryRule::overshootFilter
+
+    This property specifies the aggregation function that will be applied to
+    the intercepted property value.
+
+    If this is set to \c BoundaryRule.None (the default), the intercepted
+    property will hold a value whose overshoot is limited to \l currentOvershoot.
+    If this is set to \c BoundaryRule.Peak, the intercepted property will hold
+    a value whose overshoot is limited to \l peakOvershoot.
+*/
+QQuickBoundaryRule::OvershootFilter QQuickBoundaryRule::overshootFilter() const
+{
+    Q_D(const QQuickBoundaryRule);
+    return d->overshootFilter;
+}
+
+void QQuickBoundaryRule::setOvershootFilter(OvershootFilter overshootFilter)
+{
+    Q_D(QQuickBoundaryRule);
+    if (d->overshootFilter == overshootFilter)
+        return;
+    d->overshootFilter = overshootFilter;
+    emit overshootFilterChanged();
+}
+
+/*!
+    \qmlmethod bool QtQuick::BoundaryRule::returnToBounds
+
+    Returns the intercepted property to a value between \l minimum and
+    \l maximum, such that \l currentOvershoot and \l peakOvershoot are both
+    zero. This will be animated if \l returnDuration is greater than zero.
+
+    Returns true if the value needed to be adjusted, or false if it was already
+    within bounds.
+*/
+bool QQuickBoundaryRule::returnToBounds()
+{
+    Q_D(QQuickBoundaryRule);
+    if (d->returnAnimationJob) {
+        qCDebug(lcBR) << "animation already in progress";
+        return true;
+    }
+    if (currentOvershoot() > 0) {
+        if (d->returnDuration > 0)
+            d->returnAnimationJob = new QQuickBoundaryReturnJob(d, maximum());
+        else
+            write(maximum());
+    } else if (currentOvershoot() < 0) {
+        if (d->returnDuration > 0)
+            d->returnAnimationJob = new QQuickBoundaryReturnJob(d, minimum());
+        else
+            write(minimum());
+    } else {
+        return false;
+    }
+    if (d->returnAnimationJob) {
+        qCDebug(lcBR) << "animating from" << d->returnAnimationJob->fromValue << "to" << d->returnAnimationJob->toValue;
+        d->returnAnimationJob->start();
+    } else {
+        d->resetOvershoot();
+        qCDebug(lcBR) << "returned to" << d->property.read();
+    }
+    return true;
+}
+
+/*!
+    \qmlproperty qreal QtQuick::BoundaryRule::easing
+
+    This property holds the easing curve to be applied in overshoot mode
+    (whenever the \l minimum or \l maximum constraint is violated, while
+    the value is still within the respective overshoot range).
+
+    The default easing curve is \l QEasingCurve::OutQuad.
+*/
+QEasingCurve QQuickBoundaryRule::easing() const
+{
+    Q_D(const QQuickBoundaryRule);
+    return d->easing;
+}
+
+void QQuickBoundaryRule::setEasing(const QEasingCurve &easing)
+{
+    Q_D(QQuickBoundaryRule);
+    if (d->easing == easing)
+        return;
+    d->easing = easing;
+    emit easingChanged();
+}
+
+/*!
+    \qmlproperty int QtQuick::BoundaryRule::returnDuration
+
+    This property holds the amount of time in milliseconds that
+    \l returnToBounds() will take to return the target property to the nearest bound.
+    If it is set to 0, returnToBounds() will set the property immediately
+    rather than creating an animation job.
+
+    The default is 100 ms.
+*/
+int QQuickBoundaryRule::returnDuration() const
+{
+    Q_D(const QQuickBoundaryRule);
+    return d->returnDuration;
+}
+
+void QQuickBoundaryRule::setReturnDuration(int duration)
+{
+    Q_D(QQuickBoundaryRule);
+    if (d->returnDuration == duration)
+        return;
+    d->returnDuration = duration;
+    emit returnDurationChanged();
+}
+
+void QQuickBoundaryRule::write(const QVariant &value)
+{
+    bool conversionOk = false;
+    qreal rValue = value.toReal(&conversionOk);
+    if (!conversionOk) {
+        qWarning() << "BoundaryRule doesn't work with non-numeric values:" << value;
+        return;
+    }
+    Q_D(QQuickBoundaryRule);
+    bool bypass = !d->enabled || !d->finalized || QQmlEnginePrivate::designerMode();
+    if (bypass) {
+        QQmlPropertyPrivate::write(d->property, value,
+                                   QQmlPropertyData::BypassInterceptor | QQmlPropertyData::DontRemoveBinding);
+        return;
+    }
+
+    qmlExecuteDeferred(this);
+    d->targetValue = d->easedOvershoot(rValue);
+    QQmlPropertyPrivate::write(d->property, d->targetValue,
+                               QQmlPropertyData::BypassInterceptor | QQmlPropertyData::DontRemoveBinding);
+}
+
+void QQuickBoundaryRule::setTarget(const QQmlProperty &property)
+{
+    Q_D(QQuickBoundaryRule);
+    d->property = property;
+
+    QQmlEnginePrivate *engPriv = QQmlEnginePrivate::get(qmlEngine(this));
+    static int finalizedIdx = -1;
+    if (finalizedIdx < 0)
+        finalizedIdx = metaObject()->indexOfSlot("componentFinalized()");
+    engPriv->registerFinalizeCallback(this, finalizedIdx);
+}
+
+void QQuickBoundaryRule::componentFinalized()
+{
+    Q_D(QQuickBoundaryRule);
+    d->finalized = true;
+}
+
+/*!
+    \internal
+    Given that something is trying to set the target property to \a value,
+    this function applies the easing curve and returns the value that the
+    property should actually get instead.
+*/
+qreal QQuickBoundaryRulePrivate::easedOvershoot(qreal value)
+{
+    qreal ret = value;
+    Q_Q(QQuickBoundaryRule);
+    if (value > maximum) {
+        qreal overshootWas = currentOvershoot;
+        currentOvershoot = value - maximum;
+        if (!qFuzzyCompare(overshootWas, currentOvershoot))
+            emit q->currentOvershootChanged();
+        overshootWas = peakOvershoot;
+        peakOvershoot = qMax(currentOvershoot, peakOvershoot);
+        if (!qFuzzyCompare(overshootWas, peakOvershoot))
+            emit q->peakOvershootChanged();
+        ret = maximum + maximumOvershoot * easing.valueForProgress(
+                    (overshootFilter == QQuickBoundaryRule::OvershootFilter::Peak ? peakOvershoot : currentOvershoot)
+                    * overshootScale / maximumOvershoot);
+        qCDebug(lcBR).nospace() << value << " overshoots maximum " << maximum << " by "
+                                << currentOvershoot << " (peak " << peakOvershoot << "): eased to " << ret;
+    } else if (value < minimum) {
+        qreal overshootWas = currentOvershoot;
+        currentOvershoot = value - minimum;
+        if (!qFuzzyCompare(overshootWas, currentOvershoot))
+            emit q->currentOvershootChanged();
+        overshootWas = peakOvershoot;
+        peakOvershoot = qMin(currentOvershoot, peakOvershoot);
+        if (!qFuzzyCompare(overshootWas, peakOvershoot))
+            emit q->peakOvershootChanged();
+        ret = minimum - minimumOvershoot * easing.valueForProgress(
+                    -(overshootFilter == QQuickBoundaryRule::OvershootFilter::Peak ? peakOvershoot : currentOvershoot)
+                    * overshootScale / minimumOvershoot);
+        qCDebug(lcBR).nospace() << value << " overshoots minimum " << minimum << " by "
+                                << currentOvershoot << " (peak " << peakOvershoot << "): eased to " << ret;
+    } else {
+        resetOvershoot();
+    }
+    return ret;
+}
+
+/*!
+    \internal
+    Resets the currentOvershoot and peakOvershoot
+    properties to zero.
+*/
+void QQuickBoundaryRulePrivate::resetOvershoot()
+{
+    Q_Q(QQuickBoundaryRule);
+    if (!qFuzzyCompare(peakOvershoot, 0)) {
+        peakOvershoot = 0;
+        emit q->peakOvershootChanged();
+    }
+    if (!qFuzzyCompare(currentOvershoot, 0)) {
+        currentOvershoot = 0;
+        emit q->currentOvershootChanged();
+    }
+}
+
+QT_END_NAMESPACE
+
+#include "moc_qquickboundaryrule_p.cpp"
diff --git a/src/labs/animation/qquickboundaryrule_p.h b/src/labs/animation/qquickboundaryrule_p.h
new file mode 100644
index 0000000000..0f097b74ad
--- /dev/null
+++ b/src/labs/animation/qquickboundaryrule_p.h
@@ -0,0 +1,149 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQuick module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QQUICKBOUNDARYRULE_H
+#define QQUICKBOUNDARYRULE_H
+
+#include "qqmlanimationglobal_p.h"
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <private/qtquickglobal_p.h>
+
+#include <private/qqmlpropertyvalueinterceptor_p.h>
+#include <qqml.h>
+
+QT_BEGIN_NAMESPACE
+
+class QQuickAbstractAnimation;
+class QQuickBoundaryRulePrivate;
+class Q_LABSANIMATION_PRIVATE_EXPORT QQuickBoundaryRule : public QObject, public QQmlPropertyValueInterceptor
+{
+    Q_OBJECT
+    Q_DECLARE_PRIVATE(QQuickBoundaryRule)
+
+    Q_INTERFACES(QQmlPropertyValueInterceptor)
+    Q_PROPERTY(bool enabled READ enabled WRITE setEnabled NOTIFY enabledChanged)
+    Q_PROPERTY(qreal minimum READ minimum WRITE setMinimum NOTIFY minimumChanged)
+    Q_PROPERTY(qreal minimumOvershoot READ minimumOvershoot WRITE setMinimumOvershoot NOTIFY minimumOvershootChanged)
+    Q_PROPERTY(qreal maximum READ maximum WRITE setMaximum NOTIFY maximumChanged)
+    Q_PROPERTY(qreal maximumOvershoot READ maximumOvershoot WRITE setMaximumOvershoot NOTIFY maximumOvershootChanged)
+    Q_PROPERTY(qreal overshootScale READ overshootScale WRITE setOvershootScale NOTIFY overshootScaleChanged)
+    Q_PROPERTY(qreal currentOvershoot READ currentOvershoot NOTIFY currentOvershootChanged)
+    Q_PROPERTY(qreal peakOvershoot READ peakOvershoot NOTIFY peakOvershootChanged)
+    Q_PROPERTY(OvershootFilter overshootFilter READ overshootFilter WRITE setOvershootFilter NOTIFY overshootFilterChanged)
+    Q_PROPERTY(QEasingCurve easing READ easing WRITE setEasing NOTIFY easingChanged)
+    Q_PROPERTY(int returnDuration READ returnDuration WRITE setReturnDuration NOTIFY returnDurationChanged)
+    QML_NAMED_ELEMENT(BoundaryRule)
+    QML_ADDED_IN_VERSION(1, 0)
+
+public:
+    enum OvershootFilter {
+        None,
+        Peak
+    };
+    Q_ENUM(OvershootFilter)
+
+    QQuickBoundaryRule(QObject *parent=nullptr);
+    ~QQuickBoundaryRule();
+
+    void setTarget(const QQmlProperty &) override;
+    void write(const QVariant &value) override;
+
+    bool enabled() const;
+    void setEnabled(bool enabled);
+
+    qreal minimum() const;
+    void setMinimum(qreal minimum);
+    qreal minimumOvershoot() const;
+    void setMinimumOvershoot(qreal minimum);
+
+    qreal maximum() const;
+    void setMaximum(qreal maximum);
+    qreal maximumOvershoot() const;
+    void setMaximumOvershoot(qreal maximum);
+
+    qreal overshootScale() const;
+    void setOvershootScale(qreal scale);
+
+    qreal currentOvershoot() const;
+    qreal peakOvershoot() const;
+
+    OvershootFilter overshootFilter() const;
+    void setOvershootFilter(OvershootFilter overshootFilter);
+
+    Q_INVOKABLE bool returnToBounds();
+
+    QEasingCurve easing() const;
+    void setEasing(const QEasingCurve &easing);
+
+    int returnDuration() const;
+    void setReturnDuration(int duration);
+
+Q_SIGNALS:
+    void enabledChanged();
+    void minimumChanged();
+    void minimumOvershootChanged();
+    void maximumChanged();
+    void maximumOvershootChanged();
+    void overshootScaleChanged();
+    void currentOvershootChanged();
+    void peakOvershootChanged();
+    void overshootFilterChanged();
+    void easingChanged();
+    void returnDurationChanged();
+
+private Q_SLOTS:
+    void componentFinalized();
+};
+
+QT_END_NAMESPACE
+
+QML_DECLARE_TYPE(QQuickBoundaryRule)
+
+#endif // QQUICKBOUNDARYRULE_H