z-bar-qt/Plugins/ZShell/Components/snapview.cpp

#include "snapview.hpp"

#include <QQuickWindow>
#include <QTimer>
#include <private/qquickflickable_p.h>
#include <private/qquickflickable_p_p.h>
#include <algorithm>
#include <cmath>
#include <limits>

namespace ZShell::components {
namespace {

// The same device-pixel helpers SnapLayout uses: the residual is the fractional
// part of an absolute device-pixel position, which is how a sub-pixel move of
// the view or its ancestors is noticed without reacting to whole-pixel moves.
qint64 originResidual(qreal logical, qreal dpr) {
	const qreal device = logical * dpr;
	return std::llround((device - std::floor(device)) * 1024.0) % 1024;
}

QPointF absoluteOrigin(const QQuickItem* item) {
	qreal x = 0.0;
	qreal y = 0.0;
	for (const QQuickItem* it = item; it; it = it->parentItem()) {
		x += it->x();
		y += it->y();
	}
	return QPointF(x, y);
}

constexpr int AsyncBatchSize = 4;

// Sizes are compared with a tolerance rather than ==, because the snapped
// logical values are quotients of device pixels and never exact.
bool differs(qreal a, qreal b) {
	return qAbs(a - b) > 0.001;
}

// Geometry is watched to notice sub-pixel moves; Destroyed is watched so a
// listener can be dropped while the item is still valid instead of at teardown.
constexpr QFlags<QQuickItemPrivate::ChangeType> WatchedChanges =
	QQuickItemPrivate::Geometry | QQuickItemPrivate::Destroyed;

void addGeometryListener(QQuickItem* item, QQuickItemChangeListener* listener) {
	if (item)
		QQuickItemPrivate::get(item)->addItemChangeListener(
			listener, WatchedChanges);
}

void removeGeometryListener(
	QQuickItem* item, QQuickItemChangeListener* listener) {
	if (item)
		QQuickItemPrivate::get(item)->removeItemChangeListener(
			listener, WatchedChanges);
}

} // namespace

SnapView::SnapView(QQuickItem* parent) : QQuickFlickable(parent) {
	setClip(true);

	// Asynchronous batches are spread over event loop turns, so the frames
	// between them can render; polish() from updatePolish would run them all
	// inside one polish flush.
	m_asyncTimer = new QTimer(this);
	m_asyncTimer->setSingleShot(true);
	m_asyncTimer->setInterval(0);
	connect(m_asyncTimer, &QTimer::timeout, this, &SnapView::polish);
}

SnapView::~SnapView() {
	clearListeners();
	disconnectModel();
}

QAbstractItemModel* SnapView::model() const {
	return m_model.data();
}

void SnapView::setModel(QAbstractItemModel* model) {
	if (m_model == model) return;

	disconnectModel();
	for (int index : m_items.keys())
		destroyDelegate(index);
	m_sizeDevCache.clear();
	m_rowSizes.clear();

	m_model = model;
	invalidateRoleNames();
	connectModel();
	rebuildRows();

	if (m_componentComplete) polish();
	emit modelChanged();
}

QQmlComponent* SnapView::delegate() const {
	return m_delegate.data();
}

void SnapView::setDelegate(QQmlComponent* delegate) {
	if (m_delegate == delegate) return;

	m_delegate = delegate;
	for (int index : m_items.keys())
		destroyDelegate(index);
	m_pendingCreate.clear();
	m_sizeDevCache.clear();

	if (m_componentComplete) polish();
	emit delegateChanged();
}

Qt::Orientation SnapView::orientation() const {
	return m_orientation;
}

void SnapView::setOrientation(Qt::Orientation orientation) {
	if (m_orientation == orientation) return;
	m_orientation = orientation;
	invalidateMainAxisCaches();
	if (m_componentComplete) polish();
	emit orientationChanged();
}

qreal SnapView::spacing() const {
	return m_spacing;
}

void SnapView::setSpacing(qreal spacing) {
	if (qFuzzyCompare(m_spacing, spacing)) return;
	m_spacing = spacing;
	if (m_componentComplete) polish();
	emit spacingChanged();
}

qreal SnapView::cacheBuffer() const {
	return m_cacheBuffer;
}

void SnapView::setCacheBuffer(qreal buffer) {
	if (qFuzzyCompare(m_cacheBuffer, buffer)) return;
	m_cacheBuffer = buffer;
	if (m_componentComplete) polish();
	emit cacheBufferChanged();
}

qreal SnapView::estimatedSize() const {
	return m_estimatedSize;
}

void SnapView::setEstimatedSize(qreal size) {
	if (qFuzzyCompare(m_estimatedSize, size)) return;
	m_estimatedSize = size;
	if (m_componentComplete) polish();
	emit estimatedSizeChanged();
}

bool SnapView::snapSizes() const {
	return m_snapSizes;
}

void SnapView::setSnapSizes(bool snapSizes) {
	if (m_snapSizes == snapSizes) return;
	m_snapSizes = snapSizes;
	if (m_componentComplete) polish();
	emit snapSizesChanged();
}

bool SnapView::asynchronous() const {
	return m_asynchronous;
}

void SnapView::setAsynchronous(bool asynchronous) {
	if (m_asynchronous == asynchronous) return;
	m_asynchronous = asynchronous;
	if (m_componentComplete) polish();
	emit asynchronousChanged();
}

int SnapView::count() const {
	return m_model ? m_model->rowCount() : 0;
}

int SnapView::currentIndex() const {
	return m_currentIndex;
}

void SnapView::setCurrentIndex(int index) {
	if (m_currentIndex == index) return;
	m_currentIndex = index;
	emit currentIndexChanged();
	emit currentItemChanged();
}

QQuickItem* SnapView::currentItem() const {
	return m_items.value(m_currentIndex, nullptr);
}

void SnapView::positionViewAtBeginning() {
	positionViewAtIndex(0);
}

void SnapView::positionViewAtEnd() {
	positionViewAtIndex(count() - 1);
}

void SnapView::positionViewAtIndex(int index) {
	if (!m_componentComplete || index < 0 || index >= m_rows.size()) return;

	// Summed here rather than read from m_rows, whose offsets only refresh on
	// polish: positioning must be right even when called between passes.
	const bool horiz = m_orientation == Qt::Horizontal;
	const qreal extent = horiz ? width() : height();
	const qreal spacing = effectiveSpacing();

	qreal offset = 0.0;
	qreal target = 0.0;
	qreal total = 0.0;
	for (int i = 0; i < m_rows.size(); ++i) {
		if (i == index) target = offset;
		const qreal size = rowSize(i);
		total = offset + size;
		offset += size + spacing;
	}

	const qreal position =
		std::clamp(target, 0.0, (std::max)(0.0, total - extent));
	const qint64 positionDev = std::llround(position * devicePixelRatio());
	const qreal snapped = qreal(positionDev) / devicePixelRatio();
	if (horiz)
		setContentX(snapped);
	else
		setContentY(snapped);
}

qreal SnapView::devicePixelRatio() const {
	const QQuickWindow* win = window();
	const qreal dpr = win ? win->effectiveDevicePixelRatio() : 1.0;
	return dpr > 0.0 ? dpr : 1.0;
}

void SnapView::componentComplete() {
	QQuickFlickable::componentComplete();
	m_componentComplete = true;
	rebuildRows();
	updateAncestorListeners();
	polish();
}

void SnapView::geometryChange(
	const QRectF& newGeometry, const QRectF& oldGeometry) {
	QQuickFlickable::geometryChange(newGeometry, oldGeometry);
	if (m_componentComplete && !m_placing &&
		newGeometry.size() != oldGeometry.size()) {
		polish();
	}
}

void SnapView::itemChange(ItemChange change, const ItemChangeData& value) {
	QQuickFlickable::itemChange(change, value);
	if (change == ItemSceneChange) {
		// Leaving the scene means the ancestors are going away: drop the
		// listeners now, while both sides are still whole.
		if (value.window) {
			updateAncestorListeners();
			polish();
		} else {
			clearListeners();
		}
		return;
	}
	if (change == ItemDevicePixelRatioHasChanged) {
		updateAncestorListeners();
		polish();
	}
}

void SnapView::updatePolish() {
	if (!m_componentComplete) return;
	layoutAndPlace();
	if (!m_pendingCreate.isEmpty() && m_asynchronous) m_asyncTimer->start();
}

void SnapView::itemGeometryChanged(
	QQuickItem* item, QQuickGeometryChange change, const QRectF& oldGeometry) {
	Q_UNUSED(oldGeometry)
	if (!m_componentComplete || m_placing) return;

	const qreal dpr = devicePixelRatio();

	QQuickItem* content = QQuickFlickablePrivate::get(this)->contentItem;
	const bool watched = std::any_of(
		m_ancestorListeners.constBegin(),
		m_ancestorListeners.constEnd(),
		[item](const QPointer<QQuickItem>& p) { return p == item; });
	if (item == content || watched) {
		const QPointF origin = contentOrigin();
		if (originResidual(origin.x(), dpr) != m_originResidualX ||
			originResidual(origin.y(), dpr) != m_originResidualY) {
			polish();
		}
		return;
	}

	if (change.sizeChange() && m_items.key(item, -1) >= 0) polish();
}

void SnapView::itemDestroyed(QQuickItem* item) {
	m_sizeDevCache.remove(item);
	const auto isItem = [item](const QPointer<QQuickItem>& p) {
		return p == item;
	};
	m_delegateListeners.erase(
		std::remove_if(
			m_delegateListeners.begin(), m_delegateListeners.end(), isItem),
		m_delegateListeners.end());
	m_ancestorListeners.erase(
		std::remove_if(
			m_ancestorListeners.begin(), m_ancestorListeners.end(), isItem),
		m_ancestorListeners.end());
	const int index = m_items.key(item, -1);
	if (index >= 0) {
		m_items.remove(index);
		emit currentItemChanged();
	}
}

qreal SnapView::effectiveSpacing() const {
	return qreal(std::llround(m_spacing * devicePixelRatio())) /
		   devicePixelRatio();
}

qreal SnapView::rowSize(int index) const {
	QQuickItem* item = m_items.value(index, nullptr);
	if (item) {
		const qreal measured = m_orientation == Qt::Horizontal ? item->width()
															   : item->height();
		if (measured > 0.0) return measured;
	}

	const qreal cached = m_rowSizes.value(index, 0.0);
	if (cached > 0.0) return cached;
	return m_estimatedSize > 0.0 ? m_estimatedSize : 0.0;
}

qint64 SnapView::snappedDeviceMainSize(QQuickItem* item) {
	const qreal dpr = devicePixelRatio();

	const qreal own = m_orientation == Qt::Horizontal ? item->width()
													  : item->height();
	if (own <= 0.0) return 0;

	// Reuse the cached device size while the item's own size is still within a
	// device pixel of it, so an item that only moves keeps its size.
	const qint64 cached = m_sizeDevCache.value(item, -1);
	if (cached >= 0 && qAbs(own * dpr - qreal(cached)) <= 1.0) return cached;

	const qint64 snapped = std::llround(own * dpr);
	m_sizeDevCache[item] = snapped;
	return snapped;
}

int SnapView::firstVisibleIndex() const {
	if (m_rows.isEmpty()) return 0;

	// Row ends are non-decreasing (offsets accumulate size plus spacing), so the
	// visible range can be found by binary search instead of a linear scan.
	const qreal start = m_orientation == Qt::Horizontal ? contentX()
														: contentY();
	const qreal from = (std::max)(0.0, start - m_cacheBuffer);

	const auto it = std::lower_bound(
		m_rows.constBegin(),
		m_rows.constEnd(),
		from,
		[](const Row& row, qreal value) {
			return row.exactOffset + row.exactSize < value;
		});
	return static_cast<int>(std::distance(m_rows.constBegin(), it));
}

int SnapView::lastVisibleIndex() const {
	if (m_rows.isEmpty()) return 0;

	const bool horiz = m_orientation == Qt::Horizontal;
	const qreal start = horiz ? contentX() : contentY();
	const qreal extent = horiz ? width() : height();
	const qreal to = start + extent + m_cacheBuffer;

	const auto it = std::lower_bound(
		m_rows.constBegin(),
		m_rows.constEnd(),
		to,
		[](const Row& row, qreal value) { return row.exactOffset <= value; });
	if (it == m_rows.constBegin()) return 0;
	return static_cast<int>(std::distance(m_rows.constBegin(), it)) - 1;
}

QPointF SnapView::contentOrigin() const {
	// QQuickFlickablePrivate::get has no const overload; the item private is the
	// base of the flickable private, so casting is the const path to it.
	const auto* priv = static_cast<const QQuickFlickablePrivate*>(
		QQuickItemPrivate::get(this));
	return absoluteOrigin(priv->contentItem);
}

void SnapView::layoutAndPlace() {
	const qreal dpr = devicePixelRatio();

	const bool horiz = m_orientation == Qt::Horizontal;
	const qreal spacing = effectiveSpacing();

	// Cumulative exact offsets, so the rounding below has the same exact
	// reference SnapLayout's arrangeChildren works from. Running this before
	// updateDelegates gives the viewport range to recycle against, and running
	// it again afterwards picks up sizes that changed when a re-keyed delegate
	// got a new index.
	const auto accumulate = [&]() {
		qreal offset = 0.0;
		for (int i = 0; i < m_rows.size(); ++i) {
			qreal size = rowSize(i);
			QQuickItem* item = m_items.value(i, nullptr);
			if (item) {
				const qreal measured = horiz ? item->width() : item->height();
				if (measured > 0.0) m_rowSizes[i] = measured;
			}

			m_rows[i].exactOffset = offset;
			m_rows[i].exactSize = size;
			offset += size + spacing;
		}
		return m_rows.isEmpty() ? 0.0 : offset - spacing;
	};

	accumulate();
	updateDelegates();
	const qreal total = accumulate();

	if (horiz)
		setContentWidth(qreal(std::llround(total * dpr)) / dpr);
	else
		setContentHeight(qreal(std::llround(total * dpr)) / dpr);

	QQuickItem* content = QQuickFlickablePrivate::get(this)->contentItem;
	if (!content) return;

	const QPointF origin = absoluteOrigin(content);
	const qint64 originXDev = std::llround(origin.x() * dpr);
	const qint64 originYDev = std::llround(origin.y() * dpr);
	const qint64 crossDev = std::llround((horiz ? height() : width()) * dpr);

	qint64 prevNear = 0;
	qint64 prevSizeDev = 0;
	qreal prevEndExact = 0.0;
	bool started = false;

	m_placing = true;
	for (int i = 0; i < m_rows.size(); ++i) {
		const Row& row = m_rows.at(i);
		const qreal mainExact = row.exactOffset * dpr;

		qint64 mainNear = 0;
		if (!started) {
			mainNear = std::llround(mainExact);
			started = true;
		} else {
			mainNear =
				prevNear + prevSizeDev + std::llround(mainExact - prevEndExact);
		}

		QQuickItem* item = m_items.value(i, nullptr);
		qint64 mainDev = std::llround(row.exactSize * dpr);
		if (item) {
			const qint64 ownDev = snappedDeviceMainSize(item);
			if (ownDev > 0) mainDev = ownDev;
		}

		prevEndExact = mainExact + row.exactSize * dpr;
		prevSizeDev = mainDev;
		prevNear = mainNear;

		if (!item) continue;

		const qreal mainSize = qreal(mainDev) / dpr;
		const qreal crossSize = qreal(crossDev) / dpr;

		const qreal posX = horiz
							   ? qreal(originXDev + mainNear) / dpr - origin.x()
							   : qreal(originXDev) / dpr - origin.x();
		const qreal posY =
			horiz ? qreal(originYDev) / dpr - origin.y()
				  : qreal(originYDev + mainNear) / dpr - origin.y();
		item->setPosition(QPointF(posX, posY));

		// Only the cross axis is written unconditionally. Writing the main axis
		// would replace the delegate's implicit-size fallback with an explicit
		// value, so a delegate whose content changes size could never grow
		// again. It is resized only when snapSizes asks for exactly that.
		if (horiz) {
			if (m_snapSizes && mainDev > 0 && differs(item->width(), mainSize))
				item->setWidth(mainSize);
			if (differs(item->height(), crossSize)) item->setHeight(crossSize);
		} else {
			if (differs(item->width(), crossSize)) item->setWidth(crossSize);
			if (m_snapSizes && mainDev > 0 && differs(item->height(), mainSize))
				item->setHeight(mainSize);
		}
	}
	m_placing = false;

	trackOriginResidual();
}

void SnapView::updateDelegates() {
	const int first = firstVisibleIndex();
	const int last = lastVisibleIndex();

	for (int index : m_items.keys()) {
		if (index < first || index > last) destroyDelegate(index);
	}

	QVector<int> missing;
	for (int index = first; index <= last; ++index) {
		if (m_items.contains(index))
			updateDelegateData(index);
		else
			missing.append(index);
	}

	int budget = m_asynchronous ? AsyncBatchSize
								: (std::numeric_limits<int>::max)();
	m_pendingCreate.clear();
	for (int index : std::as_const(missing)) {
		if (budget <= 0) {
			m_pendingCreate.append(index);
			continue;
		}
		(void)createDelegate(index);
		--budget;
	}
}

QQuickItem* SnapView::createDelegate(int index) {
	if (!m_delegate || !m_model || index < 0 || index >= m_model->rowCount())
		return nullptr;
	if (m_items.contains(index)) return m_items.value(index);

	// Same as LazyListView: beginCreate + setInitialProperties + completeCreate,
	// so delegates with pragma ComponentBehavior: Bound are accepted.
	auto* compContext = m_delegate->creationContext();
	if (!compContext) compContext = qmlContext(this);
	if (!compContext) return nullptr;

	QObject* obj = m_delegate->beginCreate(compContext);
	QQuickItem* item = qobject_cast<QQuickItem*>(obj);
	if (!item) {
		qWarning(
			"SnapView: delegate creation failed for row %d: %s",
			index,
			qPrintable(m_delegate->errorString()));
		if (obj) m_delegate->completeCreate();
		delete obj;
		return nullptr;
	}

	m_delegate->setInitialProperties(item, delegateProperties(index));

	QQuickItem* content = QQuickFlickablePrivate::get(this)->contentItem;
	item->setParentItem(content ? content : this);
	addGeometryListener(item, this);
	m_delegateListeners.append(item);
	m_items.insert(index, item);

	m_delegate->completeCreate();

	emit currentItemChanged();
	return item;
}

void SnapView::destroyDelegate(int index) {
	QQuickItem* item = m_items.take(index);
	if (!item) return;

	removeGeometryListener(item, this);
	m_delegateListeners.removeAll(item);
	m_sizeDevCache.remove(item);
	item->deleteLater();
	emit currentItemChanged();
}

void SnapView::updateDelegateData(int index) {
	QQuickItem* item = m_items.value(index, nullptr);
	if (!item) return;

	const QVariantMap props = delegateProperties(index);
	for (auto it = props.constBegin(); it != props.constEnd(); ++it) {
		const QByteArray name = it.key().toUtf8();
		// Scrolls refresh every visible delegate each pass; writing only the
		// values that actually changed keeps that cheap.
		if (item->property(name.constData()) == it.value()) continue;
		item->setProperty(name.constData(), it.value());
	}
}

QVariantMap SnapView::delegateProperties(int index) {
	QVariantMap props;
	if (!m_model || index < 0 || index >= m_model->rowCount()) return props;

	const QModelIndex srcIndex = m_model->index(index, 0);
	const auto& names = roleNames();
	bool hasModelData = false;

	for (auto it = names.constBegin(); it != names.constEnd(); ++it) {
		const auto name = QString::fromUtf8(it.value());
		props.insert(name, m_model->data(srcIndex, it.key()));
		if (name == QStringLiteral("modelData")) hasModelData = true;
	}

	props.insert(QStringLiteral("index"), index);

	if (!hasModelData) {
		const auto role = names.isEmpty() ? Qt::DisplayRole
										  : names.constBegin().key();
		props.insert(QStringLiteral("modelData"), m_model->data(srcIndex, role));
	}

	return props;
}

const QHash<int, QByteArray>& SnapView::roleNames() {
	if (!m_roleNamesValid) {
		m_roleNames = m_model ? m_model->roleNames() : QHash<int, QByteArray>();
		m_roleNamesValid = true;
	}
	return m_roleNames;
}

void SnapView::invalidateRoleNames() {
	m_roleNamesValid = false;
}

void SnapView::invalidateMainAxisCaches() {
	// Cached sizes belong to the axis that is no longer the main one.
	m_rowSizes.fill(0.0);
	m_sizeDevCache.clear();
}

void SnapView::rebuildRows() {
	m_rows.resize(count());
	m_rowSizes.resize(count());
	if (m_currentIndex >= count()) m_currentIndex = -1;
	emit countChanged();
	emit currentItemChanged();
}

void SnapView::trackOriginResidual() {
	const qreal dpr = devicePixelRatio();
	const QPointF origin = contentOrigin();
	m_originResidualX = originResidual(origin.x(), dpr);
	m_originResidualY = originResidual(origin.y(), dpr);
}

void SnapView::shiftDelegateIndices(int from, int delta) {
	if (delta == 0) return;

	QHash<int, QQuickItem*> shifted;
	for (auto it = m_items.constBegin(); it != m_items.constEnd(); ++it) {
		shifted.insert(
			it.key() >= from ? it.key() + delta : it.key(), it.value());
	}
	m_items = shifted;

	for (int& index : m_pendingCreate) {
		if (index >= from) index += delta;
	}
}

void SnapView::updateAncestorListeners() {
	QQuickItem* content = QQuickFlickablePrivate::get(this)->contentItem;
	QVector<QPointer<QQuickItem>> want;
	if (content) want.append(content);
	for (QQuickItem* it = parentItem(); it; it = it->parentItem())
		want.append(it);

	for (const QPointer<QQuickItem>& item :
		 std::as_const(m_ancestorListeners)) {
		if (item && !want.contains(item))
			removeGeometryListener(item.data(), this);
	}
	for (const QPointer<QQuickItem>& item : std::as_const(want)) {
		const bool known = std::any_of(
			m_ancestorListeners.constBegin(),
			m_ancestorListeners.constEnd(),
			[&item](const QPointer<QQuickItem>& p) { return p == item; });
		if (!known) addGeometryListener(item.data(), this);
	}
	m_ancestorListeners = want;

	trackOriginResidual();
}

void SnapView::clearListeners() {
	for (const QPointer<QQuickItem>& item : std::as_const(m_ancestorListeners))
		removeGeometryListener(item.data(), this);
	m_ancestorListeners.clear();
	m_delegateListeners.clear();
}

void SnapView::connectModel() {
	if (!m_model) return;
	m_modelConnections.append(
		QObject::connect(
			m_model,
			&QAbstractItemModel::rowsInserted,
			this,
			&SnapView::onRowsInserted));
	m_modelConnections.append(
		QObject::connect(
			m_model,
			&QAbstractItemModel::rowsAboutToBeRemoved,
			this,
			&SnapView::onRowsAboutToBeRemoved));
	m_modelConnections.append(
		QObject::connect(
			m_model,
			&QAbstractItemModel::rowsRemoved,
			this,
			&SnapView::onRowsRemoved));
	m_modelConnections.append(
		QObject::connect(
			m_model,
			&QAbstractItemModel::dataChanged,
			this,
			&SnapView::onDataChanged));
	m_modelConnections.append(
		QObject::connect(
			m_model,
			&QAbstractItemModel::modelReset,
			this,
			&SnapView::onModelReset));
	m_modelConnections.append(
		QObject::connect(
			m_model, &QAbstractItemModel::layoutChanged, this, [this]() {
				rebuildRows();
				polish();
			}));
}

void SnapView::disconnectModel() {
	for (const auto& conn : std::as_const(m_modelConnections))
		disconnect(conn);
	m_modelConnections.clear();
}

void SnapView::onRowsInserted(const QModelIndex& parent, int first, int last) {
	if (parent.isValid()) return;

	// Delegates at or after the inserted range now address a different row, and
	// the inserted rows have no measured size yet.
	shiftDelegateIndices(first, last - first + 1);
	m_rowSizes.resize(count());
	for (int index = first; index <= last; ++index)
		m_rowSizes[index] = 0.0;
	rebuildRows();
	polish();
}

void SnapView::onRowsAboutToBeRemoved(
	const QModelIndex& parent, int first, int last) {
	if (parent.isValid()) return;
	for (int index = first; index <= last; ++index)
		destroyDelegate(index);
	m_rowSizes.remove(first, last - first + 1);
	shiftDelegateIndices(last + 1, -(last - first + 1));
}

void SnapView::onRowsRemoved(const QModelIndex& parent, int first, int last) {
	if (parent.isValid()) return;
	Q_UNUSED(first)
	Q_UNUSED(last)
	rebuildRows();
	polish();
}

void SnapView::onDataChanged(
	const QModelIndex& topLeft, const QModelIndex& bottomRight) {
	if (topLeft.parent().isValid() || bottomRight.parent().isValid()) return;
	for (int index = topLeft.row(); index <= bottomRight.row(); ++index)
		updateDelegateData(index);
	// A row's content can change its size, so re-place as well.
	polish();
}

void SnapView::onModelReset() {
	for (int index : m_items.keys())
		destroyDelegate(index);
	m_sizeDevCache.clear();
	m_rowSizes.clear();
	rebuildRows();
	polish();
}

} // namespace ZShell::components