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core/boundcomponent: add BoundComponent
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4 files changed

+385
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‎src/core/CMakeLists.txt

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@@ -25,6 +25,7 @@ qt_add_library(quickshell-core STATIC
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iconimageprovider.cpp
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imageprovider.cpp
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transformwatcher.cpp
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boundcomponent.cpp
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)
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set_source_files_properties(main.cpp PROPERTIES COMPILE_DEFINITIONS GIT_REVISION="${GIT_REVISION}")

‎src/core/boundcomponent.cpp

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#include "boundcomponent.hpp"
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#include <utility>
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#include <qcontainerfwd.h>
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#include <qlogging.h>
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#include <qmetaobject.h>
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#include <qobject.h>
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#include <qobjectdefs.h>
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#include <qqmlcomponent.h>
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#include <qqmlcontext.h>
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#include <qqmlengine.h>
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#include <qqmlerror.h>
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#include <qquickitem.h>
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#include <qtmetamacros.h>
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#include "incubator.hpp"
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QObject* BoundComponent::item() const { return this->object; }
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QQmlComponent* BoundComponent::sourceComponent() const { return this->mComponent; }
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void BoundComponent::setSourceComponent(QQmlComponent* component) {
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if (component == this->mComponent) return;
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if (this->componentCompleted) {
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qWarning() << "BoundComponent.component cannot be set after creation";
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return;
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}
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this->disconnectComponent();
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this->ownsComponent = false;
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this->mComponent = component;
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if (component != nullptr) {
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QObject::connect(component, &QObject::destroyed, this, &BoundComponent::onComponentDestroyed);
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}
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emit this->sourceComponentChanged();
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}
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void BoundComponent::disconnectComponent() {
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if (this->mComponent == nullptr) return;
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if (this->ownsComponent) {
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delete this->mComponent;
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} else {
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QObject::disconnect(this->mComponent, nullptr, this, nullptr);
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}
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this->mComponent = nullptr;
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}
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void BoundComponent::onComponentDestroyed() { this->mComponent = nullptr; }
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QString BoundComponent::source() const { return this->mSource; }
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void BoundComponent::setSource(QString source) {
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if (source == this->mSource) return;
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if (this->componentCompleted) {
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qWarning() << "BoundComponent.url cannot be set after creation";
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return;
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}
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auto* context = QQmlEngine::contextForObject(this);
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auto* component = new QQmlComponent(context->engine(), context->resolvedUrl(source), this);
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if (component->isError()) {
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qWarning() << component->errorString().toStdString().c_str();
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delete component;
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} else {
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this->disconnectComponent();
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this->ownsComponent = true;
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this->mSource = std::move(source);
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this->mComponent = component;
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emit this->sourceChanged();
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emit this->sourceComponentChanged();
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}
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}
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bool BoundComponent::bindValues() const { return this->mBindValues; }
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void BoundComponent::setBindValues(bool bindValues) {
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if (this->componentCompleted) {
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qWarning() << "BoundComponent.bindValues cannot be set after creation";
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return;
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}
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this->mBindValues = bindValues;
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emit this->bindValuesChanged();
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}
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void BoundComponent::componentComplete() {
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this->QQuickItem::componentComplete();
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this->componentCompleted = true;
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this->tryCreate();
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}
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void BoundComponent::tryCreate() {
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if (this->mComponent == nullptr) {
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qWarning() << "BoundComponent has no component";
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return;
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}
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auto initialProperties = QVariantMap();
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const auto* metaObject = this->metaObject();
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for (auto i = metaObject->propertyOffset(); i < metaObject->propertyCount(); i++) {
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const auto prop = metaObject->property(i);
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if (prop.isReadable()) {
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initialProperties.insert(prop.name(), prop.read(this));
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}
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}
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this->incubator = new QsQmlIncubator(QsQmlIncubator::AsynchronousIfNested, this);
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this->incubator->setInitialProperties(initialProperties);
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// clang-format off
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QObject::connect(this->incubator, &QsQmlIncubator::completed, this, &BoundComponent::onIncubationCompleted);
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QObject::connect(this->incubator, &QsQmlIncubator::failed, this, &BoundComponent::onIncubationFailed);
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// clang-format on
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this->mComponent->create(*this->incubator, QQmlEngine::contextForObject(this));
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}
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void BoundComponent::onIncubationCompleted() {
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this->object = this->incubator->object();
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delete this->incubator;
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this->disconnectComponent();
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this->object->setParent(this);
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this->mItem = qobject_cast<QQuickItem*>(this->object);
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const auto* metaObject = this->metaObject();
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const auto* objectMetaObject = this->object->metaObject();
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if (this->mBindValues) {
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for (auto i = metaObject->propertyOffset(); i < metaObject->propertyCount(); i++) {
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const auto prop = metaObject->property(i);
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if (prop.isReadable() && prop.hasNotifySignal()) {
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const auto objectPropIndex = objectMetaObject->indexOfProperty(prop.name());
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if (objectPropIndex == -1) {
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qWarning() << "property" << prop.name()
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<< "defined on BoundComponent but not on its contained object.";
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continue;
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}
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const auto objectProp = objectMetaObject->property(objectPropIndex);
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if (objectProp.isWritable()) {
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auto* proxy = new BoundComponentPropertyProxy(this, this->object, prop, objectProp);
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proxy->onNotified(); // any changes that might've happened before connection
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} else {
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qWarning() << "property" << prop.name()
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<< "defined on BoundComponent is not writable for its contained object.";
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}
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}
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}
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}
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for (auto i = metaObject->methodOffset(); i < metaObject->methodCount(); i++) {
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const auto method = metaObject->method(i);
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if (method.name().startsWith("on") && method.name().length() > 2) {
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auto sig = QString(method.methodSignature()).sliced(2);
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if (!sig[0].isUpper()) continue;
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sig[0] = sig[0].toLower();
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auto name = sig.sliced(0, sig.indexOf('('));
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auto mostViableSignal = QMetaMethod();
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for (auto i = 0; i < objectMetaObject->methodCount(); i++) {
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const auto method = objectMetaObject->method(i);
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if (method.methodSignature() == sig) {
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mostViableSignal = method;
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break;
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}
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if (method.name() == name) {
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if (mostViableSignal.isValid()) {
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qWarning() << "Multiple candidates, so none will be attached for signal" << name;
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goto next;
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}
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mostViableSignal = method;
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}
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}
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if (!mostViableSignal.isValid()) {
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qWarning() << "Function" << method.name() << "appears to be a signal handler for" << name
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<< "but it does not match any signals on the target object";
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goto next;
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}
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QMetaObject::connect(
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this->object,
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mostViableSignal.methodIndex(),
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this,
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method.methodIndex()
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);
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}
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next:;
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}
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if (this->mItem != nullptr) {
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this->mItem->setParentItem(this);
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// clang-format off
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QObject::connect(this, &QQuickItem::widthChanged, this, &BoundComponent::updateSize);
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QObject::connect(this, &QQuickItem::heightChanged, this, &BoundComponent::updateSize);
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QObject::connect(this->mItem, &QQuickItem::implicitWidthChanged, this, &BoundComponent::updateImplicitSize);
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QObject::connect(this->mItem, &QQuickItem::implicitHeightChanged, this, &BoundComponent::updateImplicitSize);
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// clang-format on
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this->updateImplicitSize();
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this->updateSize();
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}
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emit this->loaded();
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}
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void BoundComponent::onIncubationFailed() {
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qWarning() << "Failed to create BoundComponent";
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for (auto& error: this->incubator->errors()) {
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qWarning() << error;
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}
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delete this->incubator;
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this->disconnectComponent();
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}
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void BoundComponent::updateSize() { this->mItem->setSize(this->size()); }
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void BoundComponent::updateImplicitSize() {
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this->setImplicitWidth(this->mItem->implicitWidth());
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this->setImplicitHeight(this->mItem->implicitHeight());
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}
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BoundComponentPropertyProxy::BoundComponentPropertyProxy(
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QObject* from,
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QObject* to,
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QMetaProperty fromProperty,
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QMetaProperty toProperty
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)
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: QObject(from)
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, from(from)
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, to(to)
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, fromProperty(fromProperty)
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, toProperty(toProperty) {
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const auto* metaObject = this->metaObject();
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auto method = metaObject->indexOfSlot("onNotified()");
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QMetaObject::connect(from, fromProperty.notifySignal().methodIndex(), this, method);
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}
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void BoundComponentPropertyProxy::onNotified() {
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this->toProperty.write(this->to, this->fromProperty.read(this->from));
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}

‎src/core/boundcomponent.hpp

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#pragma once
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#include <qmetaobject.h>
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#include <qobject.h>
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#include <qqmlcomponent.h>
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#include <qqmlparserstatus.h>
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#include <qquickitem.h>
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#include <qsignalmapper.h>
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#include <qtmetamacros.h>
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#include "incubator.hpp"
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///! Component loader that allows setting initial properties.
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/// Component loader that allows setting initial properties, primarily useful for
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/// escaping cyclic dependency errors.
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///
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/// Properties defined on the BoundComponent will be applied to its loaded component,
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/// including required properties, and will remain reactive. Functions created with
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/// the names of signal handlers will also be attached to signals of the loaded component.
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///
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/// ```qml {filename="MyComponent.qml"}
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/// MouseArea {
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/// required property color color;
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/// width: 100
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/// height: 100
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///
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/// Rectangle {
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/// anchors.fill: parent
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/// color: parent.color
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/// }
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/// }
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/// ```
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///
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/// ```qml
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/// BoundComponent {
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/// source: "MyComponent.qml"
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///
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/// // this is the same as assigning to `color` on MyComponent if loaded normally.
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/// property color color: "red";
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///
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/// // this will be triggered when the `clicked` signal from the MouseArea is sent.
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/// function onClicked() {
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/// color = "blue";
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/// }
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/// }
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/// ```
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class BoundComponent: public QQuickItem {
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Q_OBJECT;
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// clang-format off
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/// The loaded component. Will be null until it has finished loading.
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Q_PROPERTY(QObject* item READ item NOTIFY loaded);
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/// The source to load, as a Component.
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Q_PROPERTY(QQmlComponent* sourceComponent READ sourceComponent WRITE setSourceComponent NOTIFY sourceComponentChanged);
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/// The source to load, as a Url.
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Q_PROPERTY(QString source READ source WRITE setSource NOTIFY sourceChanged);
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/// If property values should be bound after they are initially set. Defaults to `true`.
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Q_PROPERTY(bool bindValues READ bindValues WRITE setBindValues NOTIFY bindValuesChanged);
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Q_PROPERTY(qreal implicitWidth READ implicitWidth NOTIFY implicitWidthChanged);
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Q_PROPERTY(qreal implicitHeight READ implicitHeight NOTIFY implicitHeightChanged);
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// clang-format on
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QML_ELEMENT;
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public:
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explicit BoundComponent(QQuickItem* parent = nullptr): QQuickItem(parent) {}
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void componentComplete() override;
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[[nodiscard]] QObject* item() const;
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[[nodiscard]] QQmlComponent* sourceComponent() const;
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void setSourceComponent(QQmlComponent* sourceComponent);
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[[nodiscard]] QString source() const;
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void setSource(QString source);
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[[nodiscard]] bool bindValues() const;
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void setBindValues(bool bindValues);
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signals:
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void loaded();
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void sourceComponentChanged();
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void sourceChanged();
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void bindValuesChanged();
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private slots:
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void onComponentDestroyed();
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void onIncubationCompleted();
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void onIncubationFailed();
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void updateSize();
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void updateImplicitSize();
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private:
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void disconnectComponent();
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void tryCreate();
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QString mSource;
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bool mBindValues = true;
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QQmlComponent* mComponent = nullptr;
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bool ownsComponent = false;
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QsQmlIncubator* incubator = nullptr;
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QObject* object = nullptr;
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QQuickItem* mItem = nullptr;
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bool componentCompleted = false;
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};
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class BoundComponentPropertyProxy: public QObject {
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Q_OBJECT;
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public:
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BoundComponentPropertyProxy(
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QObject* from,
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QObject* to,
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QMetaProperty fromProperty,
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QMetaProperty toProperty
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);
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public slots:
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void onNotified();
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private:
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QObject* from;
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QObject* to;
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QMetaProperty fromProperty;
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QMetaProperty toProperty;
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};

‎src/core/module.md

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@@ -17,5 +17,6 @@ headers = [
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"lazyloader.hpp",
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"easingcurve.hpp",
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"transformwatcher.hpp",
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"boundcomponent.hpp",
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]
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-----

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