Player: Removing Letterboxing in Landscape

[BuffMcBigHuge]

I love playing with EasyRPG, and kudos to all those involved.

I'm playing with the surface in Android, and I can't seem to figure out how to stretch the game's screen (variable aspect ratio) to the width of the device in landscape. Since the buttons are overlaid on the same RelativeLayout, I cannot extend the layout itself.

I came across this a few SDL APIs, but it's out of my expertise to pass the device's screen width and height to something like SDL_RenderSetLogicalSize or SDL_RenderSetScale.

Here is a example in practice:
https://www.gamedev.net/resources/_/technical/apis-and-tools/stretching-your-game-to-fit-the-screen-without-letterboxing-sdl2-r3547

Is this possible without lots of headache?

[Ghabry]

I'm quite sure I have code somewhere where I tried to achive this with SDL2 on Windows. Will try to find it again when I have some time. (this was more about Multiple of 2 scaling to get rid of pixel artifacts but ignoring aspect ratio is very similiar)

(Will also need an Android configuration option for this...)

[Ghabry]

Just dropping this here for later use. SDL_SetLogicalRenderSize must be removed:

constexpr float aspect_ratio = (float)SCREEN_TARGET_WIDTH / SCREEN_TARGET_HEIGHT;

void SdlUi::UpdateDisplay() {
    [...]
    SDL_RenderClear(sdl_renderer);

// NEW
    int window_width, window_height;
    SDL_GetWindowSize(sdl_window, &window_width, &window_height);

    float w = (float)window_width;
    float h = (float)window_height;

    SDL_Rect dst_rect;
    dst_rect.x = 0;
    dst_rect.y = 0;

    if (w / h > aspect_ratio) {
        // Landscape
        if (IsFullscreen()) {
            // Reduce to closest multiple of 240 * n
            if (h > SCREEN_TARGET_HEIGHT) {
                for (int i = SCREEN_TARGET_HEIGHT; i < INT16_MAX; i += SCREEN_TARGET_HEIGHT) {
                    if (h > i && h < i + SCREEN_TARGET_HEIGHT) {
                        h = i;
                        break;
                    }
                }
            }
        }

        // Adjust aspect ratio
        w += (aspect_ratio * h - w);
    } else {
        // Portrait
        if (IsFullscreen()) {
            // Reduce to closest multiple of 320 * n
            if (w > SCREEN_TARGET_WIDTH) {
                for (int i = SCREEN_TARGET_WIDTH; i < INT16_MAX; i += SCREEN_TARGET_WIDTH) {
                    if (w > i && w < i + SCREEN_TARGET_WIDTH) {
                        w = i;
                        break;
                    }
                }
            }
        }

        // Adjust aspect ratio
        h += (1 / aspect_ratio * w - h);
    }
    dst_rect.x = window_width / 2 - w / 2;
    dst_rect.y = window_height / 2 - h / 2;
    dst_rect.w = w;
    dst_rect.h = h;

// OLD
    SDL_RenderCopy(sdl_renderer, sdl_texture, NULL, &dst_rect);
    SDL_RenderPresent(sdl_renderer);
#endif
}

[carstene1ns]

This will crash when I am allowed to resize the SDL window to 0 pixels height... 🍭

[Ghabry]

Great, In that case we can even add an optimized codepath which directly returns at the beginning ;)