widgets: add wrapper components and managers

src/widgets/wrapper.cpp

@@ -0,0 +1,127 @@
+#include "wrapper.hpp"
+
+#include <QtQml/qqmlinfo.h>
+#include <QtQml/qqmllist.h>
+#include <qlogging.h>
+#include <qnamespace.h>
+#include <qobject.h>
+#include <qquickitem.h>
+#include <qtmetamacros.h>
+
+namespace qs::widgets {
+
+void WrapperManager::componentComplete() {
+	this->mWrapper = qobject_cast<QQuickItem*>(this->parent());
+
+	if (!this->mWrapper) {
+		QString pstr;
+		QDebug(&pstr) << this->parent();
+
+		qmlWarning(this) << "Parent of WrapperManager is not a QQuickItem. Parent: " << pstr;
+		return;
+	}
+
+	QQuickItem* child = this->mChild;
+	this->mChild = nullptr; // avoids checks for the old item in setChild.
+
+	const auto& childItems = this->mWrapper->childItems();
+
+	if (childItems.length() == 1) {
+		this->mDefaultChild = childItems.first();
+	} else if (childItems.length() != 0) {
+		this->flags.setFlag(WrapperManager::HasMultipleChildren);
+
+		if (!child && !this->flags.testFlags(WrapperManager::NullChild)) {
+			this->printChildCountWarning();
+		}
+	}
+
+	for (auto* item: childItems) {
+		if (item != child) item->setParentItem(nullptr);
+	}
+
+	if (child && !this->flags.testFlag(WrapperManager::NullChild)) {
+		this->setChild(child);
+	}
+}
+
+QQuickItem* WrapperManager::child() const { return this->mChild; }
+
+void WrapperManager::setChild(QQuickItem* child) {
+	if (child && child == this->mChild) return;
+
+	if (this->mChild != nullptr) {
+		QObject::disconnect(this->mChild, nullptr, this, nullptr);
+
+		if (this->mChild->parentItem() == this->mWrapper) {
+			this->mChild->setParentItem(nullptr);
+		}
+	}
+
+	this->mChild = child;
+	this->flags.setFlag(WrapperManager::NullChild, child == nullptr);
+
+	if (child) {
+		QObject::connect(
+		    child,
+		    &QObject::destroyed,
+		    this,
+		    &WrapperManager::onChildDestroyed,
+		    Qt::UniqueConnection
+		);
+
+		if (auto* wrapper = this->mWrapper) {
+			child->setParentItem(wrapper);
+		}
+	}
+
+	emit this->initializedChildChanged();
+	emit this->childChanged();
+}
+
+void WrapperManager::setProspectiveChild(QQuickItem* child) {
+	if (child && child == this->mChild) return;
+
+	if (!this->mWrapper) {
+		if (this->mChild) {
+			QObject::disconnect(this->mChild, nullptr, this, nullptr);
+		}
+
+		this->mChild = child;
+		this->flags.setFlag(WrapperManager::NullChild, child == nullptr);
+
+		if (child) {
+			QObject::connect(child, &QObject::destroyed, this, &WrapperManager::onChildDestroyed);
+		}
+	} else {
+		this->setChild(child);
+	}
+}
+
+void WrapperManager::unsetChild() {
+	if (!this->mWrapper) {
+		this->setProspectiveChild(nullptr);
+	} else {
+		this->setChild(this->mDefaultChild);
+
+		if (!this->mDefaultChild && this->flags.testFlag(WrapperManager::HasMultipleChildren)) {
+			this->printChildCountWarning();
+		}
+	}
+
+	this->flags.setFlag(WrapperManager::NullChild, false);
+}
+
+void WrapperManager::onChildDestroyed() {
+	this->mChild = nullptr;
+	this->unsetChild();
+	emit this->childChanged();
+}
+
+void WrapperManager::printChildCountWarning() const {
+	qmlWarning(this->mWrapper) << "Wrapper component cannot have more than one visual child.";
+	qmlWarning(this->mWrapper) << "Remove all additional children, or pick a specific component "
+	                              "to wrap using the child property.";
+}
+
+} // namespace qs::widgets