core/transformwatcher: add TransformWatcher

src/core/transformwatcher.cpp

@@ -0,0 +1,136 @@
+#include "transformwatcher.hpp"
+
+#include <qcontainerfwd.h>
+#include <qdebug.h>
+#include <qlist.h>
+#include <qlogging.h>
+#include <qobject.h>
+#include <qquickitem.h>
+#include <qquickwindow.h>
+
+void TransformWatcher::resolveChains(QQuickItem* a, QQuickItem* b, QQuickItem* commonParent) {
+	if (a == nullptr || b == nullptr) return;
+
+	auto aChain = QVector<QQuickItem*>();
+	auto bChain = QVector<QQuickItem*>();
+
+	auto* aParent = a;
+	auto* bParent = b;
+
+	// resolve the parent chain of b. if a is in the chain break early
+	while (bParent != nullptr) {
+		bChain.push_back(bParent);
+
+		if (bParent == a) {
+			aChain.push_back(a);
+			goto chainResolved;
+		}
+
+		if (bParent == commonParent) break;
+		bParent = bParent->parentItem();
+	}
+
+	// resolve the parent chain of a, breaking as soon as b is found
+	while (aParent != nullptr) {
+		aChain.push_back(aParent);
+
+		for (auto bParent = bChain.begin(); bParent != bChain.end(); bParent++) {
+			if (*bParent == aParent) {
+				bParent++;
+				bChain.erase(bParent, bChain.end());
+				goto chainResolved;
+			}
+		}
+
+		if (aParent == commonParent) break;
+		aParent = aParent->parentItem();
+	}
+
+	if (commonParent != nullptr && aParent == commonParent) {
+		qWarning() << this << "failed to find a common parent between" << a << "and" << b
+		           << "due to incorrectly set commonParent" << commonParent;
+
+		return;
+	}
+
+chainResolved:
+
+	this->parentChain = aChain;
+	if (bChain.last() == aChain.last()) bChain.removeLast();
+	this->childChain = bChain;
+
+	if (a->window() != b->window()) {
+		this->parentWindow = a->window();
+		this->childWindow = b->window();
+	} else {
+		this->parentWindow = nullptr;
+		this->childWindow = nullptr;
+	}
+}
+
+void TransformWatcher::resolveChains() {
+	this->resolveChains(this->mA, this->mB, this->mCommonParent);
+}
+
+void TransformWatcher::linkItem(QQuickItem* item) const {
+	QObject::connect(item, &QQuickItem::xChanged, this, &TransformWatcher::transformChanged);
+	QObject::connect(item, &QQuickItem::yChanged, this, &TransformWatcher::transformChanged);
+	QObject::connect(item, &QQuickItem::widthChanged, this, &TransformWatcher::transformChanged);
+	QObject::connect(item, &QQuickItem::heightChanged, this, &TransformWatcher::transformChanged);
+	QObject::connect(item, &QQuickItem::scaleChanged, this, &TransformWatcher::transformChanged);
+	QObject::connect(item, &QQuickItem::rotationChanged, this, &TransformWatcher::transformChanged);
+
+	QObject::connect(item, &QQuickItem::parentChanged, this, &TransformWatcher::recalcChains);
+	QObject::connect(item, &QQuickItem::windowChanged, this, &TransformWatcher::recalcChains);
+	QObject::connect(item, &QObject::destroyed, this, &TransformWatcher::recalcChains);
+}
+
+void TransformWatcher::linkChains() {
+	for (auto* item: this->parentChain) {
+		this->linkItem(item);
+	}
+
+	for (auto* item: this->childChain) {
+		this->linkItem(item);
+	}
+}
+
+void TransformWatcher::unlinkChains() {
+	for (auto* item: this->parentChain) {
+		QObject::disconnect(item, nullptr, this, nullptr);
+	}
+
+	for (auto* item: this->childChain) {
+		QObject::disconnect(item, nullptr, this, nullptr);
+	}
+}
+
+void TransformWatcher::recalcChains() {
+	this->unlinkChains();
+	this->resolveChains();
+	this->linkChains();
+}
+
+QQuickItem* TransformWatcher::a() const { return this->mA; }
+
+void TransformWatcher::setA(QQuickItem* a) {
+	if (this->mA == a) return;
+	this->mA = a;
+	this->recalcChains();
+}
+
+QQuickItem* TransformWatcher::b() const { return this->mB; }
+
+void TransformWatcher::setB(QQuickItem* b) {
+	if (this->mB == b) return;
+	this->mB = b;
+	this->recalcChains();
+}
+
+QQuickItem* TransformWatcher::commonParent() const { return this->mCommonParent; }
+
+void TransformWatcher::setCommonParent(QQuickItem* commonParent) {
+	if (this->mCommonParent == commonParent) return;
+	this->mCommonParent = commonParent;
+	this->resolveChains();
+}