qpropertyanimation.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qpropertyanimation.h"
#include "qanimationgroup.h"
#include "qpropertyanimation_p.h"
 
#include <QtCore/QMutex>
#include <QtCore/QHash>
#include <QtCore/private/qlocking_p.h>
 
QT_BEGIN_NAMESPACE
 
void QPropertyAnimationPrivate::updateMetaProperty()
{
    const QObject *target = targetObject.valueBypassingBindings();
    if (!target || propertyName.value().isEmpty()) {
        propertyType = QMetaType::UnknownType;
        propertyIndex = -1;
        return;
    }
 
    //propertyType will be set to a valid type only if there is a Q_PROPERTY
    //otherwise it will be set to QVariant::Invalid at the end of this function
    propertyType = target->property(propertyName.value()).userType();
    propertyIndex = target->metaObject()->indexOfProperty(propertyName.value());
 
    if (propertyType != QMetaType::UnknownType)
        convertValues(propertyType);
    if (propertyIndex == -1) {
        //there is no Q_PROPERTY on the object
        propertyType = QMetaType::UnknownType;
        if (!target->dynamicPropertyNames().contains(propertyName))
            qWarning("QPropertyAnimation: you're trying to animate a non-existing property %s of "
                     "your QObject",
                     propertyName.value().constData());
    } else if (!target->metaObject()->property(propertyIndex).isWritable()) {
        qWarning("QPropertyAnimation: you're trying to animate the non-writable property %s of "
                 "your QObject",
                 propertyName.value().constData());
    }
}
 
void QPropertyAnimationPrivate::updateProperty(const QVariant &newValue)
{
    if (state == QAbstractAnimation::Stopped)
        return;
 
    if (!targetObject)
        return;
 
    if (newValue.userType() == propertyType) {
        //no conversion is needed, we directly call the QMetaObject::metacall
        //check QMetaProperty::write for an explanation of these
        int status = -1;
        int flags = 0;
        void *argv[] = { const_cast<void *>(newValue.constData()), const_cast<QVariant *>(&newValue), &status, &flags };
        QMetaObject::metacall(targetObject, QMetaObject::WriteProperty, propertyIndex, argv);
    } else {
        targetObject->setProperty(propertyName.value().constData(), newValue);
    }
}
 
QPropertyAnimation::QPropertyAnimation(QObject *parent)
    : QVariantAnimation(*new QPropertyAnimationPrivate, parent)
{
}
 
QPropertyAnimation::QPropertyAnimation(QObject *target, const QByteArray &propertyName, QObject *parent)
    : QVariantAnimation(*new QPropertyAnimationPrivate, parent)
{
    setTargetObject(target);
    setPropertyName(propertyName);
}
 
QPropertyAnimation::~QPropertyAnimation()
{
    stop();
}
 
QObject *QPropertyAnimation::targetObject() const
{
    return d_func()->targetObject;
}
 
QBindable<QObject *> QPropertyAnimation::bindableTargetObject()
{
    return &d_func()->targetObject;
}
 
void QPropertyAnimation::setTargetObject(QObject *target)
{
    Q_D(QPropertyAnimation);
    if (d->state != QAbstractAnimation::Stopped) {
        qWarning("QPropertyAnimation::setTargetObject: you can't change the target of a running animation");
        return;
    }
 
    d->targetObject.removeBindingUnlessInWrapper();
    const QObject *oldTarget = d->targetObject.valueBypassingBindings();
    if (oldTarget == target)
        return;
 
    if (oldTarget != nullptr)
        QObject::disconnect(oldTarget, &QObject::destroyed, this, nullptr);
    d->targetObject.setValueBypassingBindings(target);
 
    if (target != nullptr) {
        QObject::connect(target, &QObject::destroyed, this,
                         [d] { d->targetObjectDestroyed(); });
    }
    d->updateMetaProperty();
    d->targetObject.notify();
}
 
QByteArray QPropertyAnimation::propertyName() const
{
    Q_D(const QPropertyAnimation);
    return d->propertyName;
}
 
void QPropertyAnimation::setPropertyName(const QByteArray &propertyName)
{
    Q_D(QPropertyAnimation);
    if (d->state != QAbstractAnimation::Stopped) {
        qWarning("QPropertyAnimation::setPropertyName: you can't change the property name of a running animation");
        return;
    }
 
    d->propertyName.removeBindingUnlessInWrapper();
 
    if (d->propertyName.valueBypassingBindings() == propertyName)
        return;
 
    d->propertyName.setValueBypassingBindings(propertyName);
    d->updateMetaProperty();
    d->propertyName.notify();
}
 
QBindable<QByteArray> QPropertyAnimation::bindablePropertyName()
{
    return &d_func()->propertyName;
}
 
bool QPropertyAnimation::event(QEvent *event)
{
    return QVariantAnimation::event(event);
}
 
void QPropertyAnimation::updateCurrentValue(const QVariant &value)
{
    Q_D(QPropertyAnimation);
    d->updateProperty(value);
}
 
void QPropertyAnimation::updateState(QAbstractAnimation::State newState,
                                     QAbstractAnimation::State oldState)
{
    Q_D(QPropertyAnimation);
 
    if (!d->targetObject && oldState == Stopped) {
        qWarning("QPropertyAnimation::updateState (%s): Changing state of an animation without "
                 "target",
                 d->propertyName.value().constData());
        return;
    }
 
    QVariantAnimation::updateState(newState, oldState);
 
    QPropertyAnimation *animToStop = nullptr;
    {
        Q_CONSTINIT static QBasicMutex mutex;
        auto locker = qt_unique_lock(mutex);
        using QPropertyAnimationPair = std::pair<QObject *, QByteArray>;
        typedef QHash<QPropertyAnimationPair, QPropertyAnimation*> QPropertyAnimationHash;
        Q_CONSTINIT static QPropertyAnimationHash hash;
 
        // in case the targetObject gets deleted, the following happens:
        // 1. targetObject's destroyed signal calls our targetObjectDestroyed.
        // 2. targetObjectDestroyed calls stop()
        // 3. QAbstractAnimation::stop() calls setState(Stopped)
        // 4. setState(Stopped) calls updateState(newState, oldState)
        // 5. we arrive here. d->targetObject is not yet set to nullptr, we can safely use it.
        Q_ASSERT(d->targetObject);
 
        QPropertyAnimationPair key(d->targetObject, d->propertyName);
        if (newState == Running) {
            d->updateMetaProperty();
            animToStop = hash.value(key, nullptr);
            hash.insert(key, this);
            locker.unlock();
            // update the default start value
            if (oldState == Stopped) {
                d->setDefaultStartEndValue(
                        d->targetObject->property(d->propertyName.value().constData()));
                //let's check if we have a start value and an end value
                const char *what = nullptr;
                if (!startValue().isValid() && (d->direction == Backward || !d->defaultStartEndValue.isValid())) {
                    what = "start";
                }
                if (!endValue().isValid() && (d->direction == Forward || !d->defaultStartEndValue.isValid())) {
                    if (what)
                        what = "start and end";
                    else
                        what = "end";
                }
                if (Q_UNLIKELY(what)) {
                    qWarning("QPropertyAnimation::updateState (%s, %s, %ls): starting an animation "
                             "without %s value",
                             d->propertyName.value().constData(),
                             d->targetObject->metaObject()->className(),
                             qUtf16Printable(d->targetObject->objectName()), what);
                }
            }
        } else if (hash.value(key) == this) {
            hash.remove(key);
        }
    }
 
    //we need to do that after the mutex was unlocked
    if (animToStop) {
        // try to stop the top level group
        QAbstractAnimation *current = animToStop;
        while (current->group() && current->state() != Stopped)
            current = current->group();
        current->stop();
    }
}
 
QT_END_NAMESPACE
 
#include "moc_qpropertyanimation.cpp"