c++ - SDL卡住(黑屏)

Question

这是我的完整代码。当我右击几次(动画正常工作)时，屏幕卡住。我认为来自 if(SDL_GetTicks() - start_time < 1000) 的台词问题出在哪里(因为处决次数太多？)？

const int SCREEN_WIDTH = 600;
const int SCREEN_HEIGHT = 500;
const int SCREEN_BPP = 32;

//The surfaces
SDL_Surface *background = NULL;
SDL_Surface *upMessage = NULL;
SDL_Surface *downMessage = NULL;
SDL_Surface *leftMessage = NULL;
SDL_Surface *rightMessage = NULL;
SDL_Surface *message = NULL;
SDL_Surface *screen = NULL;
SDL_Surface *finish = NULL;
SDL_Surface *startStop = NULL;
SDL_Surface *one = NULL;
SDL_Surface *two = NULL;
SDL_Surface *three = NULL;
SDL_Surface *four = NULL;
SDL_Surface *five = NULL;
//The event structure
SDL_Event event;

SDL_Surface *load_image( std::string filename ){
    //The image that's loaded
    SDL_Surface* loadedImage = NULL;

    //The optimized surface that will be used
    SDL_Surface* optimizedImage = NULL;

    //Load the image
    loadedImage = IMG_Load( filename.c_str() );

    //If the image loaded
    if( loadedImage != NULL )
    {
        //Create an optimized surface
        optimizedImage = SDL_DisplayFormat( loadedImage );

        //Free the old surface
        SDL_FreeSurface( loadedImage );

        //If the surface was optimized
        if( optimizedImage != NULL )
        {
            //Color key surface
            SDL_SetColorKey( optimizedImage, SDL_SRCCOLORKEY, SDL_MapRGB( optimizedImage->format, 0, 0xFF, 0xFF ) );
        }
    }

    //Return the optimized surface
    return optimizedImage;
}

void apply_surface( int x, int y, SDL_Surface* source, SDL_Surface* destination, SDL_Rect* clip = NULL )
{
    //Holds offsets
    SDL_Rect offset;

    //Get offsets
    offset.x = x;
    offset.y = y;

    //Blit
    SDL_BlitSurface( source, clip, destination, &offset );
}

bool init()
{
    //Initialize all SDL subsystems
    if( SDL_Init( SDL_INIT_EVERYTHING ) == -1 )
    {
        return false;
    }

    //Set up the screen
    screen = SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP, SDL_SWSURFACE );

    //If there was an error in setting up the screen
    if( screen == NULL )
    {
        return false;
    }

    //Set the window caption
    SDL_WM_SetCaption( "Press an Arrow Key", NULL );

    //If everything initialized fine
    return true;
}

bool load_files()
{
    //Load the background image
    background = load_image( "background .png" );
    message = load_image( "guy.png" );
    finish = load_image( "finish .png" );


    //If there was a problem in loading the background
    if( background == NULL )
    {
        return false;
    }

    //If everything loaded fine
    return true;
}

void clean_up()
{
    //Free the surfaces
    SDL_FreeSurface( background );
    SDL_FreeSurface( upMessage );
    SDL_FreeSurface( downMessage );
    SDL_FreeSurface( leftMessage );
    SDL_FreeSurface( rightMessage );
    SDL_FreeSurface( startStop );
    SDL_FreeSurface( one );
    SDL_FreeSurface( two );
    SDL_FreeSurface( three );
    SDL_FreeSurface( four );
    SDL_FreeSurface( five );
    //Quit SDL
    SDL_Quit();
}
void anim(SDL_Surface *number,std::string name[],int n){
                        number = NULL;
                        number = load_image(name[n] +".png" );
                        apply_surface( 0, 0, number, screen );
}
int main( int argc, char* args[] ){
    bool quit = false;
    bool start = true;
    bool cilj_test = true;
    int x=35,y=10;
    bool animation = false;
    Uint32 start_time = 0;
    //The timer start/stop flag
    bool running = false;
    //Initialize
    if( init() == false )
    {
        return 1;
    }

    //Load the files
    if( load_files() == false )
    {
        return 1;
    }

    //Apply the background
    apply_surface( 0, 0, background, screen );

    //While the user hasn't quit
    while( quit == false ){
        //If there's an event to handle
        if( SDL_PollEvent( &event ) ){

            //If a key was pressed
            if( event.type == SDL_KEYDOWN ){
                //Set the proper message surface
                switch( event.key.keysym.sym ){
                    case SDLK_UP:
                        break;
                    case SDLK_DOWN:
                        start=false;
                        if(y!=410 && animation==false){
                        y+=100;
                        SDL_FillRect( screen, 0, 0 );
                        background = NULL;
                        message = NULL;
                        background = load_image( "background .png" );
                        apply_surface( 0, 0, background, screen );
                        finish = load_image( "finish.png" );
                        apply_surface(506, 420, finish, screen );
                        message = load_image( "guy.png" );
                        apply_surface( x, y, message, screen );
                    //    if()
                        }
                         break;
                    case SDLK_LEFT:
                    break;
                    case SDLK_RIGHT:
                        start=false;
                        if(x!=535 && animation==false){
                        x+=100;
                        SDL_FillRect( screen, 0, 0 );
                        background = NULL;
                        message = NULL;
                        background = load_image( "background.png" );
                        apply_surface( 0, 0, background, screen );
                        finish = load_image( "finish.png" );
                        apply_surface(506, 420, finish, screen );
                        message = load_image( "guy.png" );
                        apply_surface( x, y, message, screen );
                        if(x==535 && y==410){
                            start_time=SDL_GetTicks();
                            animation=true;
                            x=35,y=10;
                        }

                        }
                        break;
                }
            }
            //If the user has Xed out the window
            else if( event.type == SDL_QUIT )
            {
                //Quit the program
                quit = true;
            }
        }

        if(animation){
            std::string name[5]={"one","two","three","four","five"};
          if(SDL_GetTicks() -  start_time < 1000){
               anim(one,name,4);
            } else  if(SDL_GetTicks() -  start_time > 1000 && SDL_GetTicks() -  start_time < 2000){
               anim(two,name,3);
            } else  if(SDL_GetTicks() -  start_time > 2000 && SDL_GetTicks() -  start_time < 3000){
               anim(three,name,2);
            } else  if(SDL_GetTicks() -  start_time > 3000 && SDL_GetTicks() -  start_time < 4000){
               anim(four,name,1);
            } else if(SDL_GetTicks() -  start_time > 4000 && SDL_GetTicks() -  start_time < 5000){
               anim(five,name,0);
            } else if(SDL_GetTicks() -  start_time > 5000){
                        SDL_FillRect( screen, 0, 0 );
                        background = NULL;
                        message = NULL;
                        background = load_image( "background.png" );
                        apply_surface( 0, 0, background, screen );
                        finish = load_image( "finish.png" );
                        apply_surface(506, 420, finish, screen );
                        message = load_image( "guy.png" );
                        apply_surface( x, y, message, screen );
                        animation=false;
                        start_time=0;
            }
        }

        if( message != NULL ){
            if(start){
            apply_surface(35, 10, message, screen );
            apply_surface(506, 420, finish, screen );
            }

            message = NULL;
        }

        //Update the screen
        if( SDL_Flip( screen ) == -1 ){
            return 1;
        }
    }

    //Clean up
    clean_up();

    return 0;
}

Answer 1

您的代码有两个问题。

1. 您没有 while 循环，这意味着应用程序将绘制一次，获得一个输入，然后停止。您正在遇到卡住，因为事件队列中的事件太多。

2. 不是您问题的真正原因，但它最终会出现。每次要绘制图像时都在加载图像。而是加载之前的所有图像，然后只应用正确的表面。如果您不加载图像并且不释放它们将不会导致内存不足。

编辑:

在看到你的整个代码后，第二个问题就是问题所在。在循环之前加载所有图像，并相应地 blit 它们。