Add XCUI runtime screen stack helper

engine/include/XCEngine/UI/Runtime/UIScreenStackController.h

@@ -0,0 +1,54 @@
+#pragma once
+
+#include <XCEngine/UI/Runtime/UISystem.h>
+
+#include <cstddef>
+#include <string>
+#include <vector>
+
+namespace XCEngine {
+namespace UI {
+namespace Runtime {
+
+struct UIScreenStackEntry {
+    UIScreenLayerId layerId = 0;
+    UIScreenAsset asset = {};
+    UIScreenLayerOptions options = {};
+};
+
+class UIScreenStackController {
+public:
+    explicit UIScreenStackController(UISystem& system);
+
+    UIScreenLayerId PushScreen(
+        const UIScreenAsset& asset,
+        const UIScreenLayerOptions& options = UIScreenLayerOptions());
+    UIScreenLayerId PushMenu(
+        const UIScreenAsset& asset,
+        const std::string& debugName = {});
+    UIScreenLayerId PushModal(
+        const UIScreenAsset& asset,
+        const std::string& debugName = {});
+    UIScreenLayerId PushHud(
+        const UIScreenAsset& asset,
+        const std::string& debugName = {});
+
+    bool ReplaceTop(
+        const UIScreenAsset& asset,
+        const UIScreenLayerOptions& options = UIScreenLayerOptions());
+    bool Pop();
+    bool Remove(UIScreenLayerId layerId);
+    void Clear();
+
+    std::size_t GetEntryCount() const;
+    const UIScreenStackEntry* GetTop() const;
+    const std::vector<UIScreenStackEntry>& GetEntries() const;
+
+private:
+    UISystem* m_system = nullptr;
+    std::vector<UIScreenStackEntry> m_entries = {};
+};
+
+} // namespace Runtime
+} // namespace UI
+} // namespace XCEngine