How to getting an Image on the Screen using SDL

1. How to getting an Image on the Screen using SDL

Here some global variables.

//The window be rendering to
SDL_Window* gWindow = NULL;
 
//The surface contained by the window
SDL_Surface* gScreenSurface = NULL;

//The image will load and show on the screen
SDL_Surface* gHelloWorld = NULL;

In the load media function load our image using SDL_LoadBMP. SDL_LoadBMP takes in the path of a bmp file and returns the loaded surface. If the function returns NULL, that means it failed so print to the console an error using SDL_GetError.

bool loadMedia()
{
    //Loading success flag
    bool success = true;

    //Load splash image
    gHelloWorld = SDL_LoadBMP( "02_getting_an_image_on_the_screen/hello_world.bmp" );
    if( gHelloWorld == NULL )
    {
        printf( "Unable to load image %s! SDL Error: %s\n", "02_getting_an_image_on_the_screen/hello_world.bmp", SDL_GetError() );
        success = false;
    }

    return success;
}

void close()
{
    //Deallocate surface
    SDL_FreeSurface( gHelloWorld );
    gHelloWorld = NULL;

    //Destroy window
    SDL_DestroyWindow( gWindow );
    gWindow = NULL;

    //Quit SDL subsystems
    SDL_Quit();
}


Make sure to get into the habit of having your pointers point to NULL when they're not pointing to anything.

int main( int argc, char* args[] )
{
    //Start up SDL and create window
    if( !init() )
    {
        printf( "Failed to initialize!\n" );
    }
    else
    {
        //Load media
        if( !loadMedia() )
        {
            printf( "Failed to load media!\n" );
        }
        else
        {
            //Apply the image
            SDL_BlitSurface( gHelloWorld, NULL, gScreenSurface, NULL );