added opengl hook

examples/example_opengl_hook/CMakeLists.txt

@@ -0,0 +1,13 @@
+project(example_opengl_hook)
+
+add_library(${PROJECT_NAME} MODULE dllmain.cpp)
+
+set_target_properties(${PROJECT_NAME} PROPERTIES
+    CXX_STANDARD 23
+    MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>"
+    ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_SOURCE_DIR}/out/${CMAKE_BUILD_TYPE}"
+    LIBRARY_OUTPUT_DIRECTORY "${CMAKE_SOURCE_DIR}/out/${CMAKE_BUILD_TYPE}"
+    RUNTIME_OUTPUT_DIRECTORY "${CMAKE_SOURCE_DIR}/out/${CMAKE_BUILD_TYPE}")
+
+find_package(imgui CONFIG REQUIRED)
+target_link_libraries(${PROJECT_NAME} PRIVATE omath::omath imgui::imgui opengl32 gdi32)

examples/example_opengl_hook/dllmain.cpp

@@ -0,0 +1,116 @@
+#include "omath/hooks/hooks_manager.hpp"
+#include <Windows.h>
+#include <chrono>
+#include <imgui.h>
+#include <imgui_impl_opengl3.h>
+#include <imgui_impl_win32.h>
+#include <optional>
+#include <thread>
+
+extern IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandler(HWND, UINT, WPARAM, LPARAM);
+
+namespace
+{
+    bool g_initialized = false;
+    bool g_init_attempted = false;
+    bool g_show_menu = true;
+
+    constexpr auto g_module_wait_delay = std::chrono::milliseconds{100};
+
+    void init(HDC hdc)
+    {
+        g_init_attempted = true;
+
+        const HWND hwnd = WindowFromDC(hdc);
+        if (!hwnd)
+            return;
+
+        ImGui::CreateContext();
+        ImGui::StyleColorsDark();
+        ImGui::GetIO().IniFilename = nullptr;
+        ImGui::GetIO().LogFilename = nullptr;
+        ImGui::GetIO().ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange;
+
+        ImGui_ImplWin32_Init(hwnd);
+        ImGui_ImplOpenGL3_Init();
+
+        auto& mgr = omath::hooks::HooksManager::get();
+        mgr.set_on_wnd_proc(
+                [](HWND h, UINT msg, WPARAM wp, LPARAM lp) -> std::optional<LRESULT>
+                {
+                    if (!g_show_menu)
+                        return std::nullopt;
+
+                    if (ImGui_ImplWin32_WndProcHandler(h, msg, wp, lp))
+                        return 0;
+                    return std::nullopt;
+                });
+        (void)mgr.hook_wnd_proc(hwnd);
+
+        g_initialized = true;
+    }
+
+    void on_swap_buffers(HDC hdc)
+    {
+        if (!g_initialized)
+        {
+            if (!g_init_attempted)
+                init(hdc);
+            return;
+        }
+
+        if (GetAsyncKeyState(VK_INSERT) & 1)
+            g_show_menu = !g_show_menu;
+
+        ImGui_ImplOpenGL3_NewFrame();
+        ImGui_ImplWin32_NewFrame();
+        ImGui::NewFrame();
+
+        if (g_show_menu)
+        {
+            ImGui::SetNextWindowSize({300.f, 100.f}, ImGuiCond_Once);
+            ImGui::SetNextWindowPos({10.f, 10.f}, ImGuiCond_Once);
+            ImGui::Begin("omath | OpenGL hook");
+            ImGui::Text("Hook active");
+            ImGui::Text("FPS: %.1f", ImGui::GetIO().Framerate);
+            ImGui::Text("INSERT toggles this window");
+            ImGui::End();
+        }
+
+        ImGui::Render();
+        ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
+    }
+
+    void hook_when_opengl_is_loaded()
+    {
+        while (!GetModuleHandle("opengl32.dll"))
+            std::this_thread::sleep_for(g_module_wait_delay);
+
+        auto& mgr = omath::hooks::HooksManager::get();
+        mgr.set_on_opengl_swap_buffers(on_swap_buffers);
+        (void)mgr.hook_opengl();
+    }
+} // namespace
+
+BOOL WINAPI DllMain(HINSTANCE h_instance, DWORD reason, LPVOID)
+{
+    if (reason == DLL_PROCESS_ATTACH)
+    {
+        DisableThreadLibraryCalls(h_instance);
+        std::thread{hook_when_opengl_is_loaded}.detach();
+    }
+    else if (reason == DLL_PROCESS_DETACH)
+    {
+        auto& mgr = omath::hooks::HooksManager::get();
+        mgr.unhook_wnd_proc();
+        mgr.unhook_opengl();
+
+        if (g_initialized)
+        {
+            ImGui_ImplOpenGL3_Shutdown();
+            ImGui_ImplWin32_Shutdown();
+            ImGui::DestroyContext();
+        }
+    }
+    return true;
+}