Model UI overlay lifetime in ui core

src/ui_core/overlay_lifetime.h

@@ -0,0 +1,54 @@
+#pragma once
+
+#include "foundation/result.h"
+#include "ui_core/node_lifetime.h"
+
+#include <cstdint>
+#include <cstddef>
+#include <vector>
+
+namespace pp::ui {
+
+enum class UiOverlayKind : std::uint8_t {
+    popup,
+    dialog,
+};
+
+struct UiOverlayEntry {
+    NodeHandle node {};
+    NodeHandle parent {};
+    UiOverlayKind kind = UiOverlayKind::popup;
+    bool captures_pointer = false;
+    bool captures_keyboard = false;
+};
+
+class UiOverlayLifetime {
+public:
+    UiOverlayLifetime(NodeLifetimeTree& tree, NodeHandle root) noexcept;
+
+    [[nodiscard]] pp::foundation::Result<NodeHandle> open_popup();
+    [[nodiscard]] pp::foundation::Result<NodeHandle> open_child_popup(NodeHandle parent_popup);
+    [[nodiscard]] pp::foundation::Result<NodeHandle> open_dialog(bool modal);
+    [[nodiscard]] pp::foundation::Status close(NodeHandle overlay) noexcept;
+    void clear_for_layout_reload() noexcept;
+
+    [[nodiscard]] bool tracks(NodeHandle overlay) const noexcept;
+    [[nodiscard]] std::size_t overlay_count() const noexcept;
+    [[nodiscard]] pp::foundation::Result<NodeHandle> top_overlay() const noexcept;
+
+private:
+    [[nodiscard]] pp::foundation::Result<NodeHandle> open_overlay(
+        NodeHandle parent,
+        UiOverlayKind kind,
+        bool captures_pointer,
+        bool captures_keyboard);
+    void prune_dead_entries() noexcept;
+    void restore_capture(UiCaptureKind kind) noexcept;
+    [[nodiscard]] bool tracked_alive(NodeHandle overlay) const noexcept;
+
+    NodeLifetimeTree& tree_;
+    NodeHandle root_ {};
+    std::vector<UiOverlayEntry> entries_;
+};
+
+}