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Hello Mobile - Your First Mobile SDL 2 App

Hello Mobile - Your First Mobile SDL 2 App screenshot

Last Updated: Jan 10th, 2024

Now that you covered the hard part of getting the application to compile and run, let's go over the application code.
//Screen dimensions
SDL_Rect gScreenRect = { 0, 0, 320, 240 };
Since mobile devices vary a lot in resolution, we're going to use variable screen dimensions instead of constant ones.
        //Get device display mode
        SDL_DisplayMode displayMode;
        if( SDL_GetCurrentDisplayMode( 0, &displayMode ) == 0 )
        {
            gScreenRect.w = displayMode.w;
            gScreenRect.h = displayMode.h;
        }

        //Create window
        gWindow = SDL_CreateWindow( "SDL Tutorial", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, gScreenRect.w, gScreenRect.h, SDL_WINDOW_SHOWN );
        if( gWindow == NULL )
        {
            SDL_Log( "Window could not be created! SDL Error: %s\n", SDL_GetError() );
            success = false;
        }
Here we call SDL_GetCurrentDisplayMode to get the resolution of the mobile device. We then create a window using the device dimensions.

Notice how we're using SDL_Log instead of printf. This is because Android/iOS have their own platform specific ways to print to the console and SDL gives us a nice wrapper to make our code cross platform.
int main( int argc, char* args[] )
{
    //Start up SDL and create window
    if( !init() )
    {
        SDL_Log( "Failed to initialize!\n" );
    }
    else
    {
        //Load media
        if( !loadMedia() )
        {
            SDL_Log( "Failed to load media!\n" );
        }
        else
        {
            //Main loop flag
            bool quit = false;

            //Event handler
            SDL_Event e;

            //While application is running
            while( !quit )
            {
                //Handle events on queue
                while( SDL_PollEvent( &e ) != 0 )
                {
                    //User requests quit
                    if( e.type == SDL_QUIT )
                    {
                        quit = true;
                    }
                }

                //Clear screen
                SDL_SetRenderDrawColor( gRenderer, 0xFF, 0xFF, 0xFF, 0xFF );
                SDL_RenderClear( gRenderer );

                //Render splash
                gSplashTexture.render( ( gScreenRect.w - gSplashTexture.getWidth() ) / 2, ( gScreenRect.h - gSplashTexture.getHeight() ) / 2 );

                //Update screen
                SDL_RenderPresent( gRenderer );
            }
        }
    }

    //Free resources and close SDL
    close();

    return 0;
}
Other than the fact that we're using SDL_Log, the code is pretty much the same as before.