core/popupanchor: rework popup anchoring and add PopupAnchor

src/core/popupanchor.hpp

@@ -0,0 +1,157 @@
+#pragma once
+
+#include <optional>
+
+#include <QtQmlIntegration/qqmlintegration.h>
+#include <qflags.h>
+#include <qnamespace.h>
+#include <qobject.h>
+#include <qpoint.h>
+#include <qqmlintegration.h>
+#include <qtclasshelpermacros.h>
+#include <qtmetamacros.h>
+#include <qwindow.h>
+
+#include "doc.hpp"
+#include "proxywindow.hpp"
+#include "types.hpp"
+
+///! Adjustment strategy for popups that do not fit on screen.
+/// Adjustment strategy for popups. See @@PopupAnchor.adjustment.
+///
+/// Adjustment flags can be combined with the `|` operator.
+///
+/// `Flip` will be applied first, then `Slide`, then `Resize`.
+namespace PopupAdjustment { // NOLINT
+Q_NAMESPACE;
+QML_ELEMENT;
+
+enum Enum {
+	None = 0,
+	/// If the X axis is constrained, the popup will slide along the X axis until it fits onscreen.
+	SlideX = 1,
+	/// If the Y axis is constrained, the popup will slide along the Y axis until it fits onscreen.
+	SlideY = 2,
+	/// Alias for `SlideX | SlideY`.
+	Slide = SlideX | SlideY,
+	/// If the X axis is constrained, the popup will invert its horizontal gravity if any.
+	FlipX = 4,
+	/// If the Y axis is constrained, the popup will invert its vertical gravity if any.
+	FlipY = 8,
+	/// Alias for `FlipX | FlipY`.
+	Flip = FlipX | FlipY,
+	/// If the X axis is constrained, the width of the popup will be reduced to fit on screen.
+	ResizeX = 16,
+	/// If the Y axis is constrained, the height of the popup will be reduced to fit on screen.
+	ResizeY = 32,
+	/// Alias for `ResizeX | ResizeY`
+	Resize = ResizeX | ResizeY,
+	/// Alias for `Flip | Slide | Resize`.
+	All = Slide | Flip | Resize,
+};
+Q_ENUM_NS(Enum);
+Q_DECLARE_FLAGS(Flags, Enum);
+
+} // namespace PopupAdjustment
+
+Q_DECLARE_OPERATORS_FOR_FLAGS(PopupAdjustment::Flags);
+
+struct PopupAnchorState {
+	bool operator==(const PopupAnchorState& other) const;
+
+	Box rect = {0, 0, 1, 1};
+	Edges::Flags edges = Edges::Top | Edges::Left;
+	Edges::Flags gravity = Edges::Bottom | Edges::Right;
+	PopupAdjustment::Flags adjustment = PopupAdjustment::Slide;
+	QPoint anchorpoint;
+};
+
+///! Anchorpoint or positioner for popup windows.
+class PopupAnchor: public QObject {
+	Q_OBJECT;
+	// clang-format off
+	/// The window to anchor / attach the popup to.
+	Q_PROPERTY(QObject* window READ window WRITE setWindow NOTIFY windowChanged);
+	/// The anchorpoints the popup will attach to. Which anchors will be used is
+	/// determined by the @@edges, @@gravity, and @@adjustment.
+	///
+	/// If you leave @@edges, @@gravity and @@adjustment at their default values,
+	/// setting more than `x` and `y` does not matter.
+	///
+	/// > [!INFO] The anchor rect cannot be smaller than 1x1 pixels.
+	Q_PROPERTY(Box rect READ rect WRITE setRect NOTIFY rectChanged);
+	/// The point on the anchor rectangle the popup should anchor to.
+	/// Opposing edges suchs as `Edges.Left | Edges.Right` are not allowed.
+	///
+	/// Defaults to `Edges.Top | Edges.Left`.
+	Q_PROPERTY(Edges::Flags edges READ edges WRITE setEdges NOTIFY edgesChanged);
+	/// The direction the popup should expand towards, relative to the anchorpoint.
+	/// Opposing edges suchs as `Edges.Left | Edges.Right` are not allowed.
+	///
+	/// Defaults to `Edges.Bottom | Edges.Right`.
+	Q_PROPERTY(Edges::Flags gravity READ gravity WRITE setGravity NOTIFY gravityChanged);
+	/// The strategy used to adjust the popup's position if it would otherwise not fit on screen,
+	/// based on the anchor @@rect, preferred @@edges, and @@gravity.
+	///
+	/// See the documentation for @@PopupAdjustment for details.
+	Q_PROPERTY(PopupAdjustment::Flags adjustment READ adjustment WRITE setAdjustment NOTIFY adjustmentChanged);
+	// clang-format on
+	QML_ELEMENT;
+	QML_UNCREATABLE("");
+
+public:
+	explicit PopupAnchor(QObject* parent): QObject(parent) {}
+
+	[[nodiscard]] bool isDirty() const;
+	void markClean();
+	void markDirty();
+
+	[[nodiscard]] QObject* window() const;
+	[[nodiscard]] ProxyWindowBase* proxyWindow() const;
+	[[nodiscard]] QWindow* backingWindow() const;
+	void setWindow(QObject* window);
+
+	[[nodiscard]] Box rect() const;
+	void setRect(Box rect);
+
+	[[nodiscard]] Edges::Flags edges() const;
+	void setEdges(Edges::Flags edges);
+
+	[[nodiscard]] Edges::Flags gravity() const;
+	void setGravity(Edges::Flags gravity);
+
+	[[nodiscard]] PopupAdjustment::Flags adjustment() const;
+	void setAdjustment(PopupAdjustment::Flags adjustment);
+
+	void updateAnchorpoint(const QPoint& anchorpoint);
+
+signals:
+	void windowChanged();
+	QSDOC_HIDE void backingWindowVisibilityChanged();
+	void rectChanged();
+	void edgesChanged();
+	void gravityChanged();
+	void adjustmentChanged();
+
+private slots:
+	void onWindowDestroyed();
+
+private:
+	QObject* mWindow = nullptr;
+	ProxyWindowBase* mProxyWindow = nullptr;
+	PopupAnchorState state;
+	std::optional<PopupAnchorState> lastState;
+};
+
+class PopupPositioner {
+public:
+	explicit PopupPositioner() = default;
+	virtual ~PopupPositioner() = default;
+	Q_DISABLE_COPY_MOVE(PopupPositioner);
+
+	virtual void reposition(PopupAnchor* anchor, QWindow* window, bool onlyIfDirty = true);
+	[[nodiscard]] virtual bool shouldRepositionOnMove() const;
+
+	static PopupPositioner* instance();
+	static void setInstance(PopupPositioner* instance);
+};