z-bar-qt/Plugins/ZShell/Components/snaplayout.hpp

#pragma once

#include <QHash>
#include <QPointer>
#include <QtMath>
#include <QtGui/private/qabstractlayoutstyleinfo_p.h>
#include <QtGui/private/qgridlayoutengine_p.h>
#include <QtQuickLayouts/private/qquickgridlayoutengine_p.h>
#include <QtQuickLayouts/private/qquicklayout_p.h>
#include <QtQuick/private/qquickitem_p.h>
#include <qqmlintegration.h>

namespace ZShell::components {

class SnapLayout;
class SnapLayoutPrivate;

class SnapLayoutStyleInfo : public QAbstractLayoutStyleInfo {
	public:
	qreal spacing(Qt::Orientation orientation) const override;
	qreal windowMargin(Qt::Orientation orientation) const override;
	bool hasChangedCore() const override;
};

class SnapGridLayoutEngine : public QGridLayoutEngine {
	public:
	SnapGridLayoutEngine() : QGridLayoutEngine(Qt::AlignVCenter, false) {}

	QQuickGridLayoutItem* findLayoutItem(QQuickItem* item) const {
		for (int i = int(q_items.size()) - 1; i >= 0; --i) {
			QQuickGridLayoutItem* layoutItem =
				static_cast<QQuickGridLayoutItem*>(q_items.at(i));
			if (layoutItem->layoutItem() == item) return layoutItem;
		}
		return nullptr;
	}
};

class SnapGridLayoutItem : public QQuickGridLayoutItem {
	public:
	SnapGridLayoutItem(
		QQuickItem* item,
		int row,
		int column,
		int rowSpan,
		int columnSpan,
		Qt::Alignment alignment);

	void setGeometry(const QRectF& rect) override;

	QRectF engineRect;
	bool placed = false;
};

class SnapLayout : public QQuickLayout {
	Q_OBJECT
	QML_ELEMENT

	Q_PROPERTY(
		Qt::Orientation orientation READ orientation WRITE setOrientation NOTIFY
			orientationChanged)
	Q_PROPERTY(qreal spacing READ spacing WRITE setSpacing NOTIFY spacingChanged)
	Q_PROPERTY(
		Qt::LayoutDirection layoutDirection READ layoutDirection WRITE
			setLayoutDirection NOTIFY layoutDirectionChanged)
	Q_PROPERTY(
		bool uniformCellSizes READ uniformCellSizes WRITE setUniformCellSizes
			NOTIFY uniformCellSizesChanged)

	public:
	explicit SnapLayout(QQuickItem* parent = nullptr);
	~SnapLayout() override;

	void componentComplete() override;
	QSizeF sizeHint(Qt::SizeHint whichSizeHint) const override;
	void setAlignment(QQuickItem* item, Qt::Alignment align) override;
	void setStretchFactor(
		QQuickItem* item, int stretchFactor, Qt::Orientation orient) override;
	void invalidate(QQuickItem* childItem = nullptr) override;
	void updateLayoutItems() override;
	QQuickItem* itemAt(int index) const override;
	int itemCount() const override;
	void rearrange(const QSizeF& size) override;

	void itemChange(ItemChange change, const ItemChangeData& value) override;

	void geometryChange(
		const QRectF& newGeometry, const QRectF& oldGeometry) override;

	void itemDestroyed(QQuickItem* item) override;
	void itemVisibilityChanged(QQuickItem* item) override;
	void itemGeometryChanged(
		QQuickItem* item,
		QQuickGeometryChange change,
		const QRectF& oldGeometry) override;

	Qt::Orientation orientation() const;
	void setOrientation(Qt::Orientation orientation);

	qreal spacing() const;
	void setSpacing(qreal spacing);

	Qt::LayoutDirection layoutDirection() const;
	void setLayoutDirection(Qt::LayoutDirection direction);
	Qt::LayoutDirection effectiveLayoutDirection() const;

	bool uniformCellSizes() const;
	void setUniformCellSizes(bool uniformCellSizes);

	signals:
	void orientationChanged();
	void spacingChanged();
	void layoutDirectionChanged();
	void uniformCellSizesChanged();

	private:
	Q_DECLARE_PRIVATE(SnapLayout)

	void insertLayoutItems();
	void removeGridItem(QGridLayoutItem* gridItem);

	void arrangeChildren();

	// Re-arranges when the origin moved by a fraction of a device pixel.
	void rearrangeForOriginMove();

	void applySpacing();

	void updateAncestorListeners();
	void clearAncestorListeners();
};

class SnapLayoutPrivate : public QQuickLayoutPrivate {
	Q_DECLARE_PUBLIC(SnapLayout)

	public:
	SnapLayoutPrivate() = default;

	void mirrorChange() override;

	SnapGridLayoutEngine engine;
	SnapLayoutStyleInfo* styleInfo = nullptr;
	Qt::Orientation orientation = Qt::Horizontal;
	Qt::LayoutDirection layoutDirection = Qt::LeftToRight;
	qreal spacingRequest = qQNaN();
	bool rearranging = false;
	int recurRearrangeCounter = 0;
	QList<QQuickItem*> invalidateAfterRearrange;

	QVector<QPointer<QQuickItem>> ancestorListeners;
	QHash<QQuickItem*, QFlags<QQuickItemPrivate::ChangeType>> ancestorMasks;
	qint64 originResidualX = -1;
	qint64 originResidualY = -1;

	struct ChildSize {
		qint64 engineWidth = 0;
		qint64 engineHeight = 0;
		qint64 width = 0;
		qint64 height = 0;
	};
	QHash<QQuickItem*, ChildSize> childSizes;
};

} // namespace ZShell::components