CommonHostInterface: Add save state selector UI

src/frontend-common/save_state_selector_ui.h

@@ -0,0 +1,63 @@
+#pragma once
+#include "common_host_interface.h"
+#include "common/timer.h"
+#include <memory>
+
+class HostDisplayTexture;
+
+namespace FrontendCommon {
+
+class SaveStateSelectorUI
+{
+public:
+  static constexpr float DEFAULT_OPEN_TIME = 5.0f;
+
+  SaveStateSelectorUI(CommonHostInterface* host_interface);
+  ~SaveStateSelectorUI();
+
+  ALWAYS_INLINE bool IsOpen() const { return m_open; }
+  ALWAYS_INLINE void ResetOpenTimer() { m_open_timer.Reset(); }
+
+  void Open(float open_time = DEFAULT_OPEN_TIME);
+  void Close();
+
+  void ClearList();
+  void RefreshList();
+
+  const char* GetSelectedStatePath() const;
+  s32 GetSelectedStateSlot() const;
+
+  void SelectNextSlot();
+  void SelectPreviousSlot();
+
+  void Draw();
+
+  void LoadCurrentSlot();
+  void SaveCurrentSlot();
+
+private:
+  struct ListEntry
+  {
+    std::string path;
+    std::string game_code;
+    std::string title;
+    std::string formatted_timestamp;
+    std::unique_ptr<HostDisplayTexture> preview_texture;
+    s32 slot;
+    bool global;
+  };
+
+  void InitializePlaceholderListEntry(ListEntry* li, s32 slot, bool global);
+  void InitializeListEntry(ListEntry* li, HostInterface::ExtendedSaveStateInfo* ssi);
+
+  CommonHostInterface* m_host_interface;
+  std::vector<ListEntry> m_slots;
+  u32 m_current_selection = 0;
+
+  Common::Timer m_open_timer;
+  float m_open_time = 0.0f;
+
+  bool m_open = false;
+};
+
+} // namespace FrontendCommon