Add core popup overlay primitive

engine/include/XCEngine/UI/Widgets/UIPopupOverlayModel.h

@@ -0,0 +1,113 @@
+#pragma once
+
+#include <XCEngine/UI/Input/UIInputPath.h>
+#include <XCEngine/UI/Types.h>
+
+#include <cstddef>
+#include <cstdint>
+#include <string>
+#include <string_view>
+#include <vector>
+
+namespace XCEngine {
+namespace UI {
+namespace Widgets {
+
+enum class UIPopupPlacement : std::uint8_t {
+    BottomStart = 0,
+    BottomEnd,
+    TopStart,
+    TopEnd,
+    RightStart,
+    RightEnd,
+    LeftStart,
+    LeftEnd
+};
+
+enum class UIPopupDismissReason : std::uint8_t {
+    None = 0,
+    Programmatic,
+    EscapeKey,
+    PointerOutside,
+    FocusLoss
+};
+
+struct UIPopupPlacementResult {
+    UIRect rect = {};
+    UIPopupPlacement effectivePlacement = UIPopupPlacement::BottomStart;
+    bool clampedX = false;
+    bool clampedY = false;
+};
+
+struct UIPopupOverlayEntry {
+    std::string popupId = {};
+    std::string parentPopupId = {};
+    UIRect anchorRect = {};
+    UIInputPath anchorPath = {};
+    UIInputPath surfacePath = {};
+    UIPopupPlacement placement = UIPopupPlacement::BottomStart;
+    bool dismissOnPointerOutside = true;
+    bool dismissOnEscape = true;
+    bool dismissOnFocusLoss = true;
+};
+
+struct UIPopupOverlayMutationResult {
+    bool changed = false;
+    std::string openedPopupId = {};
+    std::vector<std::string> closedPopupIds = {};
+    UIPopupDismissReason dismissReason = UIPopupDismissReason::None;
+};
+
+UIPopupPlacementResult ResolvePopupPlacementRect(
+    const UIRect& anchorRect,
+    const UISize& popupSize,
+    const UIRect& viewportRect,
+    UIPopupPlacement placement);
+
+class UIPopupOverlayModel {
+public:
+    static constexpr std::size_t InvalidIndex = static_cast<std::size_t>(-1);
+
+    const std::vector<UIPopupOverlayEntry>& GetPopupChain() const {
+        return m_popupChain;
+    }
+
+    bool HasOpenPopups() const {
+        return !m_popupChain.empty();
+    }
+
+    std::size_t GetPopupCount() const {
+        return m_popupChain.size();
+    }
+
+    const UIPopupOverlayEntry* GetRootPopup() const;
+    const UIPopupOverlayEntry* GetTopmostPopup() const;
+    const UIPopupOverlayEntry* FindPopup(std::string_view popupId) const;
+
+    UIPopupOverlayMutationResult OpenPopup(UIPopupOverlayEntry entry);
+    UIPopupOverlayMutationResult ClosePopup(
+        std::string_view popupId,
+        UIPopupDismissReason dismissReason = UIPopupDismissReason::Programmatic);
+    UIPopupOverlayMutationResult CloseAll(
+        UIPopupDismissReason dismissReason = UIPopupDismissReason::Programmatic);
+    UIPopupOverlayMutationResult DismissFromEscape();
+    UIPopupOverlayMutationResult DismissFromPointerDown(const UIInputPath& hitPath);
+    UIPopupOverlayMutationResult DismissFromFocusLoss(const UIInputPath& focusedPath);
+
+private:
+    std::size_t FindPopupIndex(std::string_view popupId) const;
+    std::size_t FindDeepestContainingPopupIndex(const UIInputPath& path) const;
+    UIPopupOverlayMutationResult CloseFromIndex(
+        std::size_t index,
+        UIPopupDismissReason dismissReason);
+
+    static bool PopupContainsPath(
+        const UIPopupOverlayEntry& entry,
+        const UIInputPath& path);
+
+    std::vector<UIPopupOverlayEntry> m_popupChain = {};
+};
+
+} // namespace Widgets
+} // namespace UI
+} // namespace XCEngine