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Extensions and Changing Orientation - Handling Orientation Changes

Extensions and Changing Orientation - Handling Orientation Changes screenshot

Last Updated: May 28th, 2024

Now that we got SDL_image loading PNGs, it's time to handle when our mobile device rotates.
//Screen dimensions
SDL_Rect gScreenRect = { 0, 0, 320, 240 };

//Scene textures
LTexture gPortraitTexture;
LTexture gLandscapeTexture;
For this application we'll be having a different textures render depending on whether the device is in portrait or landscape mode.
        //Create window
        gWindow = SDL_CreateWindow( "SDL Tutorial", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, gScreenRect.w, gScreenRect.h, SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE );
When you rotate your device, the height/width of the window changes which means the window size changes. In order to support rotation, the window needs to be created as resizable.
                //Handle events on queue
                while( SDL_PollEvent( &e ) != 0 )
                {
                    //User requests quit
                    if( e.type == SDL_QUIT )
                    {
                        quit = true;
                    }
                    //Window event
                    else if( e.type == SDL_WINDOWEVENT )
                    {
                        //Window resize/orientation change
                        if( e.window.event == SDL_WINDOWEVENT_SIZE_CHANGED )
                        {
                            //Get screen dimensions
                            gScreenRect.w = e.window.data1;
                            gScreenRect.h = e.window.data2;
                            
                            //Update screen
                            SDL_RenderPresent( gRenderer );
                        }
                    }
                }
SDL 2 turns orientation change events into window change events. We check for window events and if the window event is a size change, we get the new dimensions, and update the screen.
                //Clear screen
                SDL_SetRenderDrawColor( gRenderer, 0xFF, 0xFF, 0xFF, 0xFF );
                SDL_RenderClear( gRenderer );

                //Render splash
                if( gScreenRect.h >= gScreenRect.w )
                {
                    gPortraitTexture.render( ( gScreenRect.w - gPortraitTexture.getWidth() ) / 2, ( gScreenRect.h - gPortraitTexture.getHeight() ) / 2 );    
                }
                else
                {
                    gLandscapeTexture.render( ( gScreenRect.w - gLandscapeTexture.getWidth() ) / 2, ( gScreenRect.h - gLandscapeTexture.getHeight() ) / 2 );    
                }

                //Update screen
                SDL_RenderPresent( gRenderer );
How do we tell if the device is in portrait or landscape? Simple: if the height is greater width, it's in portrait. Otherwise, it's in landscape.