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SDLWindow: MSAA fallback retry + null-safe CreateWindow #2059

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SDLWindow: MSAA fallback retry + null-safe CreateWindow #2059

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6370d46
SDLWindow: MSAA fallback retry + null-safe CreateWindow
AxGord Mar 20, 2026
cbc833f
SDLWindow: nullptr + ASCII comment; NativeWindow: null-safe create
AxGord May 17, 2026
1da6efe
Merge upstream/develop into bugfix/sdlwindow-msaa-fallback
AxGord May 17, 2026
16a34b6
SDLWindow: pass NULL for unused SDL_GetWindowSize out-param
AxGord May 17, 2026
c668007
NativeWindow: set frameRate before null-handle early return
AxGord May 17, 2026
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28 changes: 23 additions & 5 deletions project/src/backend/sdl/SDLWindow.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -160,6 +160,15 @@ namespace lime {
}
#endif

if (!sdlWindow && (flags & (WINDOW_FLAG_HW_AA | WINDOW_FLAG_HW_AA_HIRES))) {

// Retry without antialiasing — emulators and some devices don't support MSAA
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@tobil4sk tobil4sk May 17, 2026

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Maybe best to remove the emdash as it may cause issues in some editors

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@AxGord AxGord May 17, 2026

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Good catch — replaced with an ASCII hyphen in cbc833f.

SDL_GL_SetAttribute (SDL_GL_MULTISAMPLEBUFFERS, 0);
SDL_GL_SetAttribute (SDL_GL_MULTISAMPLESAMPLES, 0);
sdlWindow = SDL_CreateWindow (title, SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, width, height, sdlWindowFlags);

}

if (!sdlWindow) {

printf ("Could not create SDL window: %s.\n", SDL_GetError ());
Expand Down Expand Up @@ -584,8 +593,8 @@ namespace lime {

int SDLWindow::GetHeight () {

int width;
int height;
int width = 0;
int height = 0;
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@tobil4sk tobil4sk May 17, 2026

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Can SDL_GetWindowSize actually exit without writing these values? Sdl2 docs don't mention that case: https://wiki.libsdl.org/SDL2/SDL_GetWindowSize

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@AxGord AxGord May 17, 2026

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It can, via CHECK_WINDOW_MAGIC. In SDL2 (src/video/SDL_video.c) SDL_GetWindowSize starts with CHECK_WINDOW_MAGIC(window, );, which early-returns before writing *w/*h when the video subsystem is uninitialized, window is NULL, or window->magic doesn't match (a destroyed/stale window — the teardown race this guards). The wiki doesn't mention it but the source confirms it, so the = 0 init is defensive against exactly that path; the happy path is unaffected.

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@tobil4sk tobil4sk May 17, 2026

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Just to provide the source:
https://github.com/libsdl-org/SDL/blob/f0d1101920864995c0c265128cfd7b96eb959ac5/src/video/SDL_video.c#L2399

https://github.com/libsdl-org/SDL/blob/f0d1101920864995c0c265128cfd7b96eb959ac5/src/video/SDL_video.c#L161

The docs also say:

NULL can safely be passed as the w or h parameter if the width or height value is not desired.

Which can make the code cleaner and avoid setting the one we don't need to 0.

Also as an aside, it looks like in SDL3 we will be able to check the return value of SDL_GetWindowSize to see if it failed: https://wiki.libsdl.org/SDL3/SDL_GetWindowSize

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@AxGord AxGord May 17, 2026

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Good call — adopted in 16a34b6. GetWidth/GetHeight now pass NULL for the dimension they don't return and only init the one they do (still = 0 so the CHECK_WINDOW_MAGIC early-return path stays defensive). Thanks for the SDL source links and the SDL3 return-value note.


SDL_GetWindowSize (sdlWindow, &width, &height);

Expand Down Expand Up @@ -667,8 +676,8 @@ namespace lime {

int SDLWindow::GetWidth () {

int width;
int height;
int width = 0;
int height = 0;

SDL_GetWindowSize (sdlWindow, &width, &height);

Expand Down Expand Up @@ -1133,7 +1142,16 @@ namespace lime {

Window* CreateWindow (Application* application, int width, int height, int flags, const char* title) {

return new SDLWindow (application, width, height, flags, title);
SDLWindow* window = new SDLWindow (application, width, height, flags, title);

if (!window->sdlWindow) {

delete window;
return NULL;

}

return window;
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@tobil4sk tobil4sk May 17, 2026

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We have to make sure all callers of CreateWindow check for null with this change. We should also return nullptr rather than NULL since it is c++ code.

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@AxGord AxGord May 17, 2026

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Done — nullptr in cbc833f. On the caller side: both C++ callers (lime_window_create / hl_window_create in ExternalInterface.cpp) pass the result straight into CFFIPointer/HLCFFIPointer, which already null-check (CFFIPointer.cpp returns alloc_null() for a null pointer; HLCFFIPointer returns 0), so the Haxe side gets a real null. NativeWindow.create() did guard the width/height/x/y block with if (handle != null), but then called lime_window_get_scale(handle) and lime_window_get_context_type(handle) unconditionally — those deref a null handle. Fixed in the same commit by replacing the partial guard with an early return right after lime_window_create.


}

Expand Down