imgui/examples/directx9_example/imgui_impl_dx9.h

// ImGui Win32 + DirectX9 binding
// You can copy and use unmodified imgui_impl_* files in your project. 
// If you use this binding you'll need to call 4 functions: ImGui_ImplXXXX_Init(), ImGui_ImplXXXX_NewFrame(), ImGui::Render() and ImGui_ImplXXXX_Shutdown().
// See main.cpp for an example of using this.
// https://github.com/ocornut/imgui

struct IDirect3DDevice9;

IMGUI_API bool        ImGui_ImplDX9_Init(void* hwnd, IDirect3DDevice9* device);
IMGUI_API void        ImGui_ImplDX9_Shutdown();
IMGUI_API void        ImGui_ImplDX9_NewFrame();

// Use if you want to reset your rendering device without losing ImGui state.
IMGUI_API void        ImGui_ImplDX9_InvalidateDeviceObjects();
IMGUI_API bool        ImGui_ImplDX9_CreateDeviceObjects();

// Handler for Win32 messages, update mouse/keyboard data.
// You may or not need this for your implementation, but it can serve as reference for handling inputs.
// Commented out to avoid dragging dependencies on <windows.h> types. You can copy the extern declaration in your code.
/*
IMGUI_API LRESULT   ImGui_ImplDX9_WndProcHandler(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);
*/