Android: Full screen mode broken

[AntTheAlchemist]

I suspect 5317703 has broken full screen mode on Android. It's difficult see what's going on fully because the behaviour changes depending on the target SDK and the testing SDK, but the main problem seems to be that the status bars and cut-outs never return when leaving full screen.

[slouken]

Can you provide testing steps, maybe using one of the existing tests?

[AntTheAlchemist]

This PR really needs to be taken out; it makes things a lot worse: It uses a mix of modern flags for entering full screen and legacy for leaving fullscreen, which get ignored and the safe area updates are broken . The status bar and nav buttons never return after entering full-screen, and the safe area never moves. It worked better before this PR.

This minimal test is the best way to see what's going on, but the behaviour changes a lot depending on the SDK:

#define SDL_MAIN_USE_CALLBACKS 1
#include <SDL3/SDL_main.h>
#include <SDL3/SDL.h>

SDL_Window* win = nullptr;
SDL_Renderer* ren = nullptr;

SDL_AppResult SDL_AppInit(void**, int, char**) {
    if(!SDL_Init(SDL_INIT_VIDEO))
        return SDL_APP_FAILURE;
    if(!SDL_CreateWindowAndRenderer(nullptr, 640, 480, SDL_WINDOW_HIGH_PIXEL_DENSITY | SDL_WINDOW_RESIZABLE, &win, &ren))
        return SDL_APP_FAILURE;
    SDL_SetRenderDrawBlendMode(ren, SDL_BLENDMODE_BLEND);
    return SDL_APP_CONTINUE;
}

SDL_AppResult SDL_AppIterate(void*) {
    SDL_SetRenderDrawColor(ren, 0, 0, 0, SDL_ALPHA_OPAQUE);
    SDL_RenderClear(ren);
    // red-fill drawable area
    SDL_SetRenderDrawColor(ren, 255, 0, 0, SDL_ALPHA_OPAQUE / 3);
    int w, h;
    SDL_GetWindowSizeInPixels(win, &w, &h);
    SDL_FRect rec = { 0, 0, (float)w, (float)h };
    SDL_RenderFillRect(ren, &rec);
    // green-fill safe area
    SDL_SetRenderDrawColor(ren, 0, 255, 0, SDL_ALPHA_OPAQUE / 3);
    SDL_Rect safe;
    SDL_GetWindowSafeArea(win, &safe);
    SDL_RectToFRect(&safe, &rec);
    SDL_RenderFillRect(ren, &rec);
    // debug info
    SDL_SetRenderDrawColor(ren, 255, 255, 255, SDL_ALPHA_OPAQUE);
    float scale = SDL_ceilf(SDL_GetWindowDisplayScale(win));
    SDL_SetRenderScale(ren, scale, scale);
    float offsetX = safe.x / scale + 10;
    float offsetY = safe.y / scale + 10;
#ifdef SDL_PLATFORM_ANDROID
    SDL_RenderDebugTextFormat(ren, offsetX, offsetY, "SDK %d", SDL_GetAndroidSDKVersion());
#endif
    SDL_RenderDebugTextFormat(ren, offsetX, offsetY + 10, "%s (%d x %d)",
        SDL_GetWindowFlags(win) & SDL_WINDOW_FULLSCREEN ? "fullscreen" : "windowed  ", w, h);
    SDL_RenderDebugTextFormat(ren, offsetX, offsetY + 20, "safe %d x %d, %d x %d",
        safe.x, safe.y, safe.w, safe.h);
    SDL_SetRenderScale(ren, 1, 1);
    SDL_RenderPresent(ren);
    return SDL_APP_CONTINUE;
}

SDL_AppResult SDL_AppEvent(void*, SDL_Event* event) {
    switch (event->type) {
        case SDL_EVENT_KEY_UP:
            if (event->key.key == SDLK_ESCAPE || event->key.key == SDLK_AC_BACK)
                return SDL_APP_SUCCESS;
            // fall through
        case SDL_EVENT_FINGER_UP: {
            SDL_SetWindowFullscreen(win, !(SDL_GetWindowFlags(win) & SDL_WINDOW_FULLSCREEN));
            break;
        }
        case SDL_EVENT_QUIT:
            return SDL_APP_SUCCESS;
    }
    return SDL_APP_CONTINUE;
}

void SDL_AppQuit(void*, SDL_AppResult result) {
    if(result == SDL_APP_FAILURE)
        SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, nullptr, SDL_GetError(), win);
}

[slouken]

@klirktag, can you take a look at this?

[klirktag]

@klirktag, can you take a look at this?

I promise to take a look at this. Unfortunately I am travelling and can't make it until next week, so if you are in a hurry you can take out the commit now, and I can come back to you next week

The PR is only tested on the phones I have which are Samsung S25 and Fairphone 3 and Fairphone 4 so this might make the testing a bit limited. What phone did you experience problems on?

As I am a developer of OpenLieroX, https://www.openlierox.net so the testing is done by building this PR together with OpenLieroX and verifying that it works on the 3 different phones I have. I could look into making a general purpose test app others can use maybe? Or SDL have a test app I can build on?

[AntTheAlchemist]

@klirktag did you test toggling between full screen and windowed? It fails to restore the status and nav bars on all devices. And the safe zone does not move; it should expand when status and nav bars are hidden. The code above is an ideal way to test this behaviour.

I have got it working on all devices now, so I can create a new PR to fix this. I just need to figure out what I changed 😂

[klirktag]

@klirktag I trust your fix and I am more than happy you provide the fix :). What devices did you test on?. Please take over and merge your working fix

@klirktag did you test toggling between full screen and windowed? It fails to restore the status and nav bars on all devices. And the safe zone does not move; it should expand when status and nav bars are hidden. The code above is an ideal way to test this behaviour.

I have got it working on all devices now, so I can create a new PR to fix this. I just need to figure out what I changed 😂

\

[AntTheAlchemist]

I'm testing on a physical Pixel 5 (API 34). And a virtual Pixel 10 (37.1), small desktop (34), and virtual phones of APIs 27, 29 & 36. Returning from full screen failed to restore the status / nav on all of them. Just tweaking the small desktop behaviour that's not really behaving on that platform.

I'll create the PR on top of your changes, and I'm happy for you to check it over first to make sure I've done it right.

[klirktag]

I'm testing on a physical Pixel 5 (API 34). And a virtual Pixel 10 (37.1), small desktop (34), and virtual phones of APIs 27, 29 & 36. Returning from full screen failed to restore the status / nav on all of them. Just tweaking the small desktop behaviour that's not really behaving on that platform.

I'll create the PR on top of your changes, and I'm happy for you to check it over first to make sure I've done it right.

Sounds good! I will also check that they work on my 3 phones when you are done then

Do you use any testing app, that imports the latest SDL when you run your tests?

[AntTheAlchemist]

I'm not using any testing app, just the above code. SDL is downloaded recently and unzipped into the Android Studio project. I noticed the change in fullscreen toggle behaviour and tracked it back to your PR.

[klirktag]

Ok, I will use the same code for my testing when you are done

I'm not using any testing app, just the above code. SDL is downloaded recently and unzipped into the Android Studio project. I noticed the change in fullscreen toggle behaviour and tracked it back to your PR.

[klirktag]

@AntTheAlchemist @slouken
Here is a fix for the leaving fullscreen on API 30+ #16001

[AntTheAlchemist]

Thanks @klirktag. The nav & status bars now return okay, thanks to #16001. I'll open new issues for the safe zone / initial window size issues.