Win32 Support + MingW CrossCompile

Win32 with dx9 support derived from the imgui example code. This adds a lot
to the renderer interface. Compilation was so far only tested with mingw
version of gcc

Author: APokorny

CMakeLists.txt

@@ -19,6 +19,8 @@ if(EMSCRIPTEN)
     set(GL_LIBRARIES GL)
 
     set(EMSCRIPTEN_ENABLED ON)
+elseif(${CMAKE_SYSTEM_NAME} STREQUAL "Windows")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++17")
 else()
     find_package(PkgConfig)
 
@@ -60,6 +62,16 @@ if(EMSCRIPTEN)
     target_link_libraries(imgui-int PUBLIC GL) # TODO GL finder does not support emscripten yet..
     target_include_directories(imgui-int PRIVATE
         $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/src/emscripten>)
+elseif(${CMAKE_SYSTEM_NAME} STREQUAL "Windows")
+    target_sources(imgui-int
+        PRIVATE
+           src/win32/select_win32_renderer.cpp
+           src/win32/select_win32_renderer.h
+           src/win32/system_integration.cpp
+           src/win32/system_integration.h
+           src/dx9/renderer.cpp
+           src/dx9/renderer.h)
+    target_link_libraries(imgui-int PRIVATE d3d9 dinput wsock32)
 elseif(GL_FOUND AND GLEW_FOUND)
     target_sources(imgui-int
         PRIVATE
@@ -69,7 +81,7 @@ elseif(GL_FOUND AND GLEW_FOUND)
     target_compile_options(imgui-int PRIVATE -DGL)
 endif()
 
-if(SDL_FOUND)
+if(SDL_FOUND AND NOT WIN32)
     target_sources(imgui-int
         PRIVATE
            src/sdl/select_sdl_renderer.h

cmake/toolchain-cross-mingw-linux.cmake

@@ -0,0 +1,14 @@
+SET(CMAKE_SYSTEM_NAME Windows)
+
+set(CMAKE_FIND_ROOT_PATH /usr/x86_64-w64-mingw32/
+    /usr/share/mingw-w64/)
+
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+
+set(COMPILER_PREFIX x86_64-w64-mingw32)
+
+set(CMAKE_CXX_COMPILER ${COMPILER_PREFIX}-c++-posix)
+set(CMAKE_C_COMPILER ${COMPILER_PREFIX}-gcc-posix)
+set(CMAKE_RC_COMPILER ${COMPILER_PREFIX}-windres)

include/imgui/renderer.h

@@ -3,17 +3,25 @@
 // internal header for replacing imgui rendering infrastructure
 
 struct ImDrawData;
-namespace imgui {
-class Renderer {
+namespace imgui
+{
+class Renderer
+{
    public:
-    Renderer() = default;
+    Renderer()          = default;
     virtual ~Renderer() = default;
+    //! Call after initial setup of imgui
+    virtual void setup_imgui() = 0;
     //! prepare font files and other data
     //! This call may occur multiple times if the hardware context got lost.
     virtual void acquire_cached_resources() = 0;
     //! renders the ui data of ImGui - but does not flush/swap..
     virtual void render_imgui_data(ImDrawData& data) = 0;
+    //! Preparation for next imgui render
+    virtual void pre_frame() = 0;
     //! Use this call to perform buffer swapping or flushing
     virtual void finish_frame() = 0;
+    //! hw buffer got resized
+    virtual void resize(size_t w, size_t h) = 0;
 };
 }  // namespace imgui

src/context.cpp

@@ -18,6 +18,7 @@ imgui::Context::Context(std::unique_ptr<SystemIntegration> integration,
     system->set_ui_call(std::move(fun));
 
     system->setup_imgui();
+    renderer->setup_imgui();
     renderer->acquire_cached_resources();
     style->apply_style();
 }

src/data_time_widgets.cpp

@@ -92,7 +92,11 @@ bool imgui::date_picker(const char* id, int& level, imgui::time_point& to_edit,
         const int days_last_mo = detail::days_in_month(this_mon == 0 ? last_year : this_year, last_mon);
         auto      first_mo     = std::chrono::system_clock::to_time_t(time_point{std::chrono::floor<months>(t.to_duration())});
         std::tm   ts;
+#ifdef WIN32
+        localtime_s(&ts, &first_mo);
+#else
         localtime_r(&first_mo, &ts);
+#endif
         const int first_wd = ts.tm_wday;
         // month year
         snprintf(buff, 32, "%s %d", names_mo[this_mon], this_year);