Review Win32 WinMain policy

CMakeLists.txt

@@ -24,7 +24,13 @@ list(APPEND CMAKE_MODULE_PATH ${HELLOIMGUI_CMAKE_PATH})
 # HelloImGui Build options
 ###############################################################################
 
-option(HELLOIMGUI_WIN32_EXECUTABLE "Under windows, hello_imgui_add_app will create apps without console, with main() as the entry point" ON)
+#------------------------------------------------------------------------------
+# Options / Windows: provide WinMain automatically
+#------------------------------------------------------------------------------
+if (WIN32)
+    option(HELLOIMGUI_WIN32_NO_CONSOLE "Under windows, build apps without Dos Console" ON)
+    option(HELLOIMGUI_WIN32_AUTO_WINMAIN "Under windows, automatically provide a WinMain (provide `int main(int, char**)`, it will be called by WinMain())" ON)
+endif()
 
 #------------------------------------------------------------------------------
 # Options / Backend selection

README.md

@@ -193,12 +193,12 @@ __Table of contents__
       * [handle events](#handle-events)
 * [Full usage instructions and API](#full-usage-instructions-and-api)
   * [Online interactive example applications](#online-interactive-example-applications)
+* [Main signature: use `int main(int, char**)`](#main-signature-use-`int-mainint-char**`)
 * [Build instructions](#build-instructions)
   * [Supported platforms and backends](#supported-platforms-and-backends)
   * [Clone the repository](#clone-the-repository)
   * [Easy build on desktop platforms using Glfw](#easy-build-on-desktop-platforms-using-glfw)
   * [Custom build: select your preferred backend](#custom-build-select-your-preferred-backend)
-    * [Warning, if using the SDL backend:](#warning-if-using-the-sdl-backend)
   * [Build instructions for iOS](#build-instructions-for-ios)
     * [Customizing the iOS build](#customizing-the-ios-build)
   * [Build instructions for emscripten](#build-instructions-for-emscripten)
@@ -225,6 +225,14 @@ __Table of contents__
 
 --------------------
 
+# Main signature: use `int main(int, char**)`
+
+Under windows, Hello ImGui will automatically provide a `WinMain()` function that will call main, 
+and expects its signature to be `int main(int, char**)`. You may get a linker error if your main function signature is for example `int main()`.
+
+You can disable this via cmake by passing `-DHELLOIMGUI_WIN32_AUTO_WINMAIN=OFF` as a command line cmake option.
+
+
 # Build instructions
 
 ## Supported platforms and backends
@@ -262,19 +270,6 @@ cmake .. -DHELLOIMGUI_USE_GLFW_OPENGL3=ON      # To use your own version of GLFW
 cmake .. -DHELLOIMGUI_USE_SDL_OPENGL3=ON       # To use your own version of SDL (it should be findable via find_package(SDL2))
 ```
 
-### Warning, if using the SDL backend:
-
-
-Warning for SDL apps under iOS and Android:
-
-SDL uses a dirty hack in order to _replace your main() function by its own main() function_,
-which will then call your own main !
-
-Please make sure that the signature of your main() function is *exactly*
-    `int main(int argc, char **argv)`
-and that your main() function returns an int.
-
-
 
 ## Build instructions for iOS
 

README.src.md

@@ -163,6 +163,14 @@ __Table of contents__
 
 --------------------
 
+# Main signature: use `int main(int, char**)`
+
+Under windows, Hello ImGui will automatically provide a `WinMain()` function that will call main, 
+and expects its signature to be `int main(int, char**)`. You may get a linker error if your main function signature is for example `int main()`.
+
+You can disable this via cmake by passing `-DHELLOIMGUI_WIN32_AUTO_WINMAIN=OFF` as a command line cmake option.
+
+
 # Build instructions
 
 ## Supported platforms and backends
@@ -200,10 +208,6 @@ cmake .. -DHELLOIMGUI_USE_GLFW_OPENGL3=ON      # To use your own version of GLFW
 cmake .. -DHELLOIMGUI_USE_SDL_OPENGL3=ON       # To use your own version of SDL (it should be findable via find_package(SDL2))
 ```
 
-### Warning, if using the SDL backend:
-
-@import "src/hello_imgui/hello_imgui.h" {md_id=SDLMain}
-
 
 ## Build instructions for iOS
 

hello_imgui_cmake/HelloImGui_WinMain.cpp

@@ -0,0 +1,11 @@
+#include <windows.h>
+
+
+int main(int, char **);
+
+
+INT WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR lpCmdLine, INT nCmdShow)
+{
+  int exit_result = main(0, NULL);
+  return exit_result;
+}

hello_imgui_cmake/hello_imgui_add_app.cmake

@@ -80,13 +80,17 @@ function(hello_imgui_add_app)
         add_executable(${app_name} ${app_sources})
     endif()
 
-    if (WIN32 AND HELLOIMGUI_WIN32_EXECUTABLE)
-        # Make this an app without console, and force it to use main() as the entry point, not WinMain()
-        # TODO: Use WinMain instead, this hack risks undefined behaviour: https://stackoverflow.com/a/72033725/7753444
-        if (MINGW)
-            target_link_options(${app_name} PRIVATE -Wl,--subsystem,windows,--entry,mainCRTStartup)
-        else() # If MSVC
-            target_link_options(${app_name} PRIVATE /SUBSYSTEM:WINDOWS /ENTRY:mainCRTStartup)
+    if (WIN32)
+        if (HELLOIMGUI_WIN32_NO_CONSOLE)
+            # Make this an app without console, and use HelloImGui_WinMain.cpp
+            if (MINGW)
+                target_link_options(${app_name} PRIVATE -Wl,--subsystem,windows)
+            else() # If MSVC
+                target_link_options(${app_name} PRIVATE /SUBSYSTEM:WINDOWS)
+            endif()
+        endif()
+        if (HELLOIMGUI_WIN32_AUTO_WINMAIN)
+            target_sources(${app_name} PRIVATE ${HELLOIMGUI_CMAKE_PATH}/HelloImGui_WinMain.cpp)
         endif()
     endif()
 

src/hello_imgui/hello_imgui.h

@@ -56,20 +56,7 @@ namespace HelloImGui
     float FrameRate(float durationForMean = 0.5f);
 }
 
-/**
-@@md#SDLMain
-
-Warning for SDL apps under iOS and Android:
-
-SDL uses a dirty hack in order to _replace your main() function by its own main() function_,
-which will then call your own main !
 
-Please make sure that the signature of your main() function is *exactly*
-    `int main(int argc, char **argv)`
-and that your main() function returns an int.
-
-@@md
-*/
 #if defined(HELLOIMGUI_USE_SDL_OPENGL3)
 #include <SDL_main.h>
 #endif