diff options
Diffstat (limited to 'src/qml/types/qqmlbind.cpp')
| -rw-r--r-- | src/qml/types/qqmlbind.cpp | 198 |
1 files changed, 183 insertions, 15 deletions
diff --git a/src/qml/types/qqmlbind.cpp b/src/qml/types/qqmlbind.cpp index 4aed0f2fee..921d60caa1 100644 --- a/src/qml/types/qqmlbind.cpp +++ b/src/qml/types/qqmlbind.cpp @@ -43,6 +43,8 @@ #include <private/qqmlproperty_p.h> #include <private/qqmlbinding_p.h> #include <private/qqmlmetatype_p.h> +#include <private/qqmlvmemetaobject_p.h> +#include <private/qv4persistent_p.h> #include <qqmlengine.h> #include <qqmlcontext.h> @@ -52,28 +54,50 @@ #include <QtCore/qfile.h> #include <QtCore/qdebug.h> #include <QtCore/qtimer.h> +#include <QtCore/qloggingcategory.h> #include <private/qobject_p.h> QT_BEGIN_NAMESPACE +Q_DECLARE_LOGGING_CATEGORY(lcBindingRemoval) + class QQmlBindPrivate : public QObjectPrivate { public: - QQmlBindPrivate() : obj(nullptr), componentComplete(true), delayed(false), pendingEval(false) {} + QQmlBindPrivate() + : obj(nullptr) + , prevBind(QQmlAbstractBinding::Ptr()) + , prevIsVariant(false) + , componentComplete(true) + , delayed(false) + , pendingEval(false) + , restoreBinding(true) + , restoreValue(false) + , restoreModeExplicit(false) + , writingProperty(false) + {} ~QQmlBindPrivate() { } QQmlNullableValue<bool> when; QPointer<QObject> obj; QString propName; - QQmlNullableValue<QVariant> value; + QQmlNullableValue<QJSValue> value; QQmlProperty prop; QQmlAbstractBinding::Ptr prevBind; + QV4::PersistentValue v4Value; + QVariant prevValue; + bool prevIsVariant:1; bool componentComplete:1; bool delayed:1; bool pendingEval:1; + bool restoreBinding:1; + bool restoreValue:1; + bool restoreModeExplicit:1; + bool writingProperty: 1; void validate(QObject *binding) const; + void clearPrev(); }; void QQmlBindPrivate::validate(QObject *binding) const @@ -175,9 +199,12 @@ QQmlBind::~QQmlBind() When the binding becomes inactive again, any direct bindings that were previously set on the property will be restored. - \note A previously set literal value is not restored when the Binding becomes inactive. Rather, - the last value set by the now inactive Binding is retained. This behavior will change in future - versions of Qt. + \note By default, a previously set literal value is not restored when the Binding becomes + inactive. Rather, the last value set by the now inactive Binding is retained. You can customize + the restoration behavior for literal values as well as bindings using the \l restoreMode + property. The default will change in Qt 6.0. + + \sa restoreMode */ bool QQmlBind::when() const { @@ -220,7 +247,7 @@ void QQmlBind::setObject(QObject *obj) } d->obj = obj; if (d->componentComplete) { - d->prop = QQmlProperty(d->obj, d->propName); + setTarget(QQmlProperty(d->obj, d->propName, qmlContext(this))); d->validate(this); } eval(); @@ -266,7 +293,7 @@ void QQmlBind::setProperty(const QString &p) } d->propName = p; if (d->componentComplete) { - d->prop = QQmlProperty(d->obj, d->propName); + setTarget(QQmlProperty(d->obj, d->propName, qmlContext(this))); d->validate(this); } eval(); @@ -278,13 +305,13 @@ void QQmlBind::setProperty(const QString &p) The value to be set on the target object and property. This can be a constant (which isn't very useful), or a bound expression. */ -QVariant QQmlBind::value() const +QJSValue QQmlBind::value() const { Q_D(const QQmlBind); return d->value.value; } -void QQmlBind::setValue(const QVariant &v) +void QQmlBind::setValue(const QJSValue &v) { Q_D(QQmlBind); d->value = v; @@ -327,9 +354,71 @@ void QQmlBind::setDelayed(bool delayed) eval(); } +/*! + \qmlproperty enumeration QtQml::Binding::restoreMode + \since 5.14 + + This property can be used to describe if and how the original value should + be restored when the binding is disabled. + + The possible values are: + \list + \li Binding.RestoreNone The original value is not restored at all + \li Binding.RestoreBinding The original value is restored if it was another + binding. In that case the old binding is in effect again. + \li Binding.RestoreValue The original value is restored if it was a plain + value rather than a binding. + \li Binding.RestoreBindingOrValue The original value is always restored. + \endlist + + \warning The default value is Binding.RestoreBinding. This will change in + Qt 6.0 to Binding.RestoreBindingOrValue. + + If you rely on any specific behavior regarding the restoration of plain + values when bindings get disabled you should migrate to explicitly set the + restoreMode. + + Reliance on a restoreMode that doesn't restore the previous binding or value + for a specific property results in a run-time warning. +*/ +QQmlBind::RestorationMode QQmlBind::restoreMode() const +{ + Q_D(const QQmlBind); + unsigned result = RestoreNone; + if (d->restoreValue) + result |= RestoreValue; + if (d->restoreBinding) + result |= RestoreBinding; + return RestorationMode(result); +} + +void QQmlBind::setRestoreMode(RestorationMode newMode) +{ + Q_D(QQmlBind); + d->restoreModeExplicit = true; + if (newMode != restoreMode()) { + d->restoreValue = (newMode & RestoreValue); + d->restoreBinding = (newMode & RestoreBinding); + emit restoreModeChanged(); + } +} + void QQmlBind::setTarget(const QQmlProperty &p) { Q_D(QQmlBind); + + if (Q_UNLIKELY(lcBindingRemoval().isInfoEnabled())) { + if (QObject *oldObject = d->prop.object()) { + QMetaProperty prop = oldObject->metaObject()->property(d->prop.index()); + if (prop.hasNotifySignal()) { + QByteArray signal('2' + prop.notifySignal().methodSignature()); + QObject::disconnect(oldObject, signal.constData(), + this, SLOT(targetValueChanged())); + } + } + p.connectNotifySignal(this, SLOT(targetValueChanged())); + } + d->prop = p; } @@ -344,7 +433,7 @@ void QQmlBind::componentComplete() Q_D(QQmlBind); d->componentComplete = true; if (!d->prop.isValid()) { - d->prop = QQmlProperty(d->obj, d->propName); + setTarget(QQmlProperty(d->obj, d->propName, qmlContext(this))); d->validate(this); } eval(); @@ -362,6 +451,14 @@ void QQmlBind::prepareEval() } } +void QQmlBindPrivate::clearPrev() +{ + prevBind = nullptr; + v4Value.clear(); + prevValue.clear(); + prevIsVariant = false; +} + void QQmlBind::eval() { Q_D(QQmlBind); @@ -373,20 +470,91 @@ void QQmlBind::eval() if (!d->when) { //restore any previous binding if (d->prevBind) { - QQmlAbstractBinding::Ptr p = d->prevBind; - d->prevBind = nullptr; - QQmlPropertyPrivate::setBinding(p.data()); + if (d->restoreBinding) { + QQmlAbstractBinding::Ptr p = d->prevBind; + d->clearPrev(); // Do that before setBinding(), as setBinding() may recurse. + QQmlPropertyPrivate::setBinding(p.data()); + } + } else if (!d->v4Value.isEmpty()) { + if (d->restoreValue) { + auto propPriv = QQmlPropertyPrivate::get(d->prop); + QQmlVMEMetaObject *vmemo = QQmlVMEMetaObject::get(propPriv->object); + Q_ASSERT(vmemo); + vmemo->setVMEProperty(propPriv->core.coreIndex(), *d->v4Value.valueRef()); + d->clearPrev(); + } else if (!d->restoreModeExplicit) { + qmlWarning(this) + << "Not restoring previous value because restoreMode has not been set." + << "This behavior is deprecated." + << "In Qt < 6.0 the default is Binding.RestoreBinding." + << "In Qt >= 6.0 the default is Binding.RestoreBindingOrValue."; + } + } else if (d->prevIsVariant) { + if (d->restoreValue) { + d->prop.write(d->prevValue); + d->clearPrev(); + } else if (!d->restoreModeExplicit) { + qmlWarning(this) + << "Not restoring previous value because restoreMode has not been set." + << "This behavior is deprecated." + << "In Qt < 6.0 the default is Binding.RestoreBinding." + << "In Qt >= 6.0 the default is Binding.RestoreBindingOrValue."; + } } return; } //save any set binding for restoration - if (!d->prevBind) + if (!d->prevBind && d->v4Value.isEmpty() && !d->prevIsVariant) { + // try binding first d->prevBind = QQmlPropertyPrivate::binding(d->prop); + + if (!d->prevBind) { // nope, try a V4 value next + auto propPriv = QQmlPropertyPrivate::get(d->prop); + auto propData = propPriv->core; + if (!propPriv->valueTypeData.isValid() && propData.isVarProperty()) { + QQmlVMEMetaObject *vmemo = QQmlVMEMetaObject::get(propPriv->object); + Q_ASSERT(vmemo); + auto retVal = vmemo->vmeProperty(propData.coreIndex()); + d->v4Value = QV4::PersistentValue(vmemo->engine, retVal); + } else { // nope, use the meta object to get a QVariant + d->prevValue = d->prop.read(); + d->prevIsVariant = true; + } + } + } + QQmlPropertyPrivate::removeBinding(d->prop); } - d->prop.write(d->value.value); + d->writingProperty = true; + d->prop.write(d->value.value.toVariant()); + d->writingProperty = false; +} + +void QQmlBind::targetValueChanged() +{ + Q_D(QQmlBind); + if (d->writingProperty) + return; + + if (d->when.isValid() && !d->when) + return; + + QUrl url; + quint16 line = 0; + + const QQmlData *ddata = QQmlData::get(this, false); + if (ddata && ddata->outerContext) { + url = ddata->outerContext->url(); + line = ddata->lineNumber; + } + + qCInfo(lcBindingRemoval, + "The target property of the Binding element created at %s:%d was changed from " + "elsewhere. This does not overwrite the binding. The target property will still be " + "updated when the value of the Binding element changes.", + qPrintable(url.toString()), line); } QT_END_NAMESPACE |