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Diffstat (limited to 'src/declarative/util/qdeclarativespringfollow.cpp')
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diff --git a/src/declarative/util/qdeclarativespringfollow.cpp b/src/declarative/util/qdeclarativespringfollow.cpp new file mode 100644 index 0000000..b26a7e2 --- /dev/null +++ b/src/declarative/util/qdeclarativespringfollow.cpp @@ -0,0 +1,464 @@ +/**************************************************************************** +** +** 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 QtDeclarative 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 "qdeclarativespringfollow_p.h" + +#include "qdeclarativeanimation_p_p.h" + +#include <QtCore/qdebug.h> + +#include <private/qobject_p.h> + +#include <limits.h> +#include <math.h> + +QT_BEGIN_NAMESPACE + + + +class QDeclarativeSpringFollowPrivate : public QObjectPrivate +{ + Q_DECLARE_PUBLIC(QDeclarativeSpringFollow) +public: + QDeclarativeSpringFollowPrivate() + : currentValue(0), sourceValue(0), maxVelocity(0), lastTime(0) + , mass(1.0), spring(0.), damping(0.), velocity(0), epsilon(0.01) + , modulus(0.0), useMass(false), haveModulus(false), enabled(true), mode(Track), clock(this) {} + + QDeclarativeMetaProperty property; + qreal currentValue; + qreal sourceValue; + qreal maxVelocity; + qreal velocityms; + int lastTime; + qreal mass; + qreal spring; + qreal damping; + qreal velocity; + qreal epsilon; + qreal modulus; + + bool useMass : 1; + bool haveModulus : 1; + bool enabled : 1; + + enum Mode { + Track, + Velocity, + Spring + }; + Mode mode; + + void tick(int); + void updateMode(); + void start(); + void stop(); + + QTickAnimationProxy<QDeclarativeSpringFollowPrivate, &QDeclarativeSpringFollowPrivate::tick> clock; +}; + +void QDeclarativeSpringFollowPrivate::tick(int time) +{ + Q_Q(QDeclarativeSpringFollow); + + int elapsed = time - lastTime; + if (!elapsed) + return; + qreal srcVal = sourceValue; + if (haveModulus) { + currentValue = fmod(currentValue, modulus); + srcVal = fmod(srcVal, modulus); + } + if (mode == Spring) { + if (elapsed < 16) // capped at 62fps. + return; + // Real men solve the spring DEs using RK4. + // We'll do something much simpler which gives a result that looks fine. + int count = elapsed / 16; + for (int i = 0; i < count; ++i) { + qreal diff = srcVal - currentValue; + if (haveModulus && qAbs(diff) > modulus / 2) { + if (diff < 0) + diff += modulus; + else + diff -= modulus; + } + if (useMass) + velocity = velocity + (spring * diff - damping * velocity) / mass; + else + velocity = velocity + spring * diff - damping * velocity; + if (maxVelocity > 0.) { + // limit velocity + if (velocity > maxVelocity) + velocity = maxVelocity; + else if (velocity < -maxVelocity) + velocity = -maxVelocity; + } + currentValue += velocity * 16.0 / 1000.0; + if (haveModulus) { + currentValue = fmod(currentValue, modulus); + if (currentValue < 0.0) + currentValue += modulus; + } + } + if (qAbs(velocity) < epsilon && qAbs(srcVal - currentValue) < epsilon) { + velocity = 0.0; + currentValue = srcVal; + clock.stop(); + } + lastTime = time - (elapsed - count * 16); + } else { + qreal moveBy = elapsed * velocityms; + qreal diff = srcVal - currentValue; + if (haveModulus && qAbs(diff) > modulus / 2) { + if (diff < 0) + diff += modulus; + else + diff -= modulus; + } + if (diff > 0) { + currentValue += moveBy; + if (haveModulus) + currentValue = fmod(currentValue, modulus); + if (currentValue > sourceValue) { + currentValue = sourceValue; + clock.stop(); + } + } else { + currentValue -= moveBy; + if (haveModulus && currentValue < 0.0) + currentValue = fmod(currentValue, modulus) + modulus; + if (currentValue < sourceValue) { + currentValue = sourceValue; + clock.stop(); + } + } + lastTime = time; + } + property.write(currentValue); + emit q->valueChanged(currentValue); + if (clock.state() != QAbstractAnimation::Running) + emit q->syncChanged(); +} + +void QDeclarativeSpringFollowPrivate::updateMode() +{ + if (spring == 0. && maxVelocity == 0.) + mode = Track; + else if (spring > 0.) + mode = Spring; + else + mode = Velocity; +} + +void QDeclarativeSpringFollowPrivate::start() +{ + if (!enabled) + return; + + Q_Q(QDeclarativeSpringFollow); + if (mode == QDeclarativeSpringFollowPrivate::Track) { + currentValue = sourceValue; + property.write(currentValue); + } else if (sourceValue != currentValue && clock.state() != QAbstractAnimation::Running) { + lastTime = 0; + currentValue = property.read().toReal(); + clock.start(); // infinity?? + emit q->syncChanged(); + } +} + +void QDeclarativeSpringFollowPrivate::stop() +{ + clock.stop(); +} + +/*! + \qmlclass SpringFollow QDeclarativeSpringFollow + \brief The SpringFollow element allows a property to track a value. + + In example below, \e rect2 will follow \e rect1 moving with a velocity of up to 200: + \code + Rectangle { + id: rect1 + width: 20; height: 20 + color: "#00ff00" + y: 200 //initial value + y: SequentialAnimation { + running: true + repeat: true + NumberAnimation { + to: 200 + easing: "easeOutBounce(amplitude:100)" + duration: 2000 + } + PauseAnimation { duration: 1000 } + } + } + Rectangle { + id: rect2 + x: rect1.width + width: 20; height: 20 + color: "#ff0000" + y: SpringFollow { source: rect1.y; velocity: 200 } + } + \endcode + + \sa EaseFollow +*/ + +QDeclarativeSpringFollow::QDeclarativeSpringFollow(QObject *parent) +: QObject(*(new QDeclarativeSpringFollowPrivate),parent) +{ +} + +QDeclarativeSpringFollow::~QDeclarativeSpringFollow() +{ +} + +void QDeclarativeSpringFollow::setTarget(const QDeclarativeMetaProperty &property) +{ + Q_D(QDeclarativeSpringFollow); + d->property = property; + d->currentValue = property.read().toReal(); +} + +qreal QDeclarativeSpringFollow::sourceValue() const +{ + Q_D(const QDeclarativeSpringFollow); + return d->sourceValue; +} + +/*! + \qmlproperty qreal SpringFollow::source + This property holds the source value which will be tracked. + + Bind to a property in order to track its changes. +*/ + +void QDeclarativeSpringFollow::setSourceValue(qreal value) +{ + Q_D(QDeclarativeSpringFollow); + if (d->clock.state() == QAbstractAnimation::Running && d->sourceValue == value) + return; + + d->sourceValue = value; + d->start(); +} + +/*! + \qmlproperty qreal SpringFollow::velocity + This property holds the maximum velocity allowed when tracking the source. +*/ + +qreal QDeclarativeSpringFollow::velocity() const +{ + Q_D(const QDeclarativeSpringFollow); + return d->maxVelocity; +} + +void QDeclarativeSpringFollow::setVelocity(qreal velocity) +{ + Q_D(QDeclarativeSpringFollow); + d->maxVelocity = velocity; + d->velocityms = velocity / 1000.0; + d->updateMode(); +} + +/*! + \qmlproperty qreal SpringFollow::spring + This property holds the spring constant + + The spring constant describes how strongly the target is pulled towards the + source. Setting spring to 0 turns off spring tracking. Useful values 0 - 5.0 + + When a spring constant is set and the velocity property is greater than 0, + velocity limits the maximum speed. +*/ +qreal QDeclarativeSpringFollow::spring() const +{ + Q_D(const QDeclarativeSpringFollow); + return d->spring; +} + +void QDeclarativeSpringFollow::setSpring(qreal spring) +{ + Q_D(QDeclarativeSpringFollow); + d->spring = spring; + d->updateMode(); +} + +/*! + \qmlproperty qreal SpringFollow::damping + This property holds the spring damping constant + + The damping constant describes how quickly a sprung follower comes to rest. + Useful range is 0 - 1.0 +*/ +qreal QDeclarativeSpringFollow::damping() const +{ + Q_D(const QDeclarativeSpringFollow); + return d->damping; +} + +void QDeclarativeSpringFollow::setDamping(qreal damping) +{ + Q_D(QDeclarativeSpringFollow); + if (damping > 1.) + damping = 1.; + + d->damping = damping; +} + + +/*! + \qmlproperty qreal SpringFollow::epsilon + This property holds the spring epsilon + + The epsilon is the rate and amount of change in the value which is close enough + to 0 to be considered equal to zero. This will depend on the usage of the value. + For pixel positions, 0.25 would suffice. For scale, 0.005 will suffice. + + The default is 0.01. Tuning this value can provide small performance improvements. +*/ +qreal QDeclarativeSpringFollow::epsilon() const +{ + Q_D(const QDeclarativeSpringFollow); + return d->epsilon; +} + +void QDeclarativeSpringFollow::setEpsilon(qreal epsilon) +{ + Q_D(QDeclarativeSpringFollow); + d->epsilon = epsilon; +} + +/*! + \qmlproperty qreal SpringFollow::modulus + This property holds the modulus value. + + Setting a \a modulus forces the target value to "wrap around" at the modulus. + For example, setting the modulus to 360 will cause a value of 370 to wrap around to 10. +*/ +qreal QDeclarativeSpringFollow::modulus() const +{ + Q_D(const QDeclarativeSpringFollow); + return d->modulus; +} + +void QDeclarativeSpringFollow::setModulus(qreal modulus) +{ + Q_D(QDeclarativeSpringFollow); + if (d->modulus != modulus) { + d->haveModulus = modulus != 0.0; + d->modulus = modulus; + emit modulusChanged(); + } +} + +/*! + \qmlproperty qreal SpringFollow::mass + This property holds the "mass" of the property being moved. + + mass is 1.0 by default. Setting a different mass changes the dynamics of + a \l spring follow. +*/ +qreal QDeclarativeSpringFollow::mass() const +{ + Q_D(const QDeclarativeSpringFollow); + return d->mass; +} + +void QDeclarativeSpringFollow::setMass(qreal mass) +{ + Q_D(QDeclarativeSpringFollow); + if (d->mass != mass && mass > 0.0) { + d->useMass = mass != 1.0; + d->mass = mass; + emit massChanged(); + } +} + +/*! + \qmlproperty qreal SpringFollow::value + The current value. +*/ + +/*! + \qmlproperty bool SpringFollow::enabled + This property holds whether the target will track the source. +*/ +bool QDeclarativeSpringFollow::enabled() const +{ + Q_D(const QDeclarativeSpringFollow); + return d->enabled; +} + +void QDeclarativeSpringFollow::setEnabled(bool enabled) +{ + Q_D(QDeclarativeSpringFollow); + d->enabled = enabled; + if (enabled) + d->start(); + else + d->stop(); +} + +/*! + \qmlproperty bool SpringFollow::inSync + This property is true when target is equal to the source; otherwise + false. If inSync is true the target is not being animated. + + If \l enabled is false then inSync will also be false. +*/ +bool QDeclarativeSpringFollow::inSync() const +{ + Q_D(const QDeclarativeSpringFollow); + return d->enabled && d->clock.state() != QAbstractAnimation::Running; +} + +qreal QDeclarativeSpringFollow::value() const +{ + Q_D(const QDeclarativeSpringFollow); + return d->currentValue; +} + +QT_END_NAMESPACE |