Question

我是SDL的新手。我正在尝试将图像添加到窗口，我已按照本教程：http://lazyfoo.net/SDL_tutorials/lesson02/index.php

我正在使用xcode中的所有代码，当我运行它时，窗口将无法加载。我只是闪过然后消失，我知道我已经完成了我应该做的所有步骤。这是我的代码：

const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
const int SCREEN_BPP = 32;

SDL_Surface *message = NULL;
SDL_Surface *background = NULL;
SDL_Surface *screen = NULL;

SDL_Surface *load_image(std::string filename)
{
    SDL_Surface *loadedImage = NULL;
    SDL_Surface *optimizedImage = NULL;

    loadedImage = SDL_LoadBMP( filename.c_str() );

    if (loadedImage != NULL)
    {
        optimizedImage = SDL_DisplayFormat(loadedImage);
        SDL_FreeSurface(loadedImage);

    }

    return optimizedImage;
}

void apply_surface(int x, int y, SDL_Surface *source, SDL_Surface *destination)
{
    SDL_Rect offset;

    offset.x = x;
    offset.y = y;

    SDL_BlitSurface(source, NULL, destination, &offset);
}



int main( int argc, char* args[] )
{
    //Start SDL
    SDL_Init( SDL_INIT_EVERYTHING );

    //Quit SDL
    SDL_Quit();

    if (SDL_Init(SDL_INIT_EVERYTHING)==-1)
    {
        return 1;
    }

    screen = SDL_SetVideoMode(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP, SDL_SWSURFACE);

    if (screen == NULL)
    {
        return 1;
    }

    SDL_WM_SetCaption("Hellow world!", NULL);

    message = load_image("images.bmp");
    background = load_image("images.bmp");

    apply_surface(0, 0, background, screen);

    apply_surface(180, 140, message, screen);

    return 0;

}

Answer 1

您在主函数中过早地调用了SDL_Quit()。此函数关闭所有SDL子系统，而应在程序结束时调用。

如果您希望窗口保持不变，直到您明确关闭它，请添加一个循环，如下所示：

int main() {
  if (SDL_Init(SDL_INIT_EVERYTHING) == -1) {
    return 1;
  }

  screen = SDL_SetVideoMode(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP, SDL_SWSURFACE);
  if (!screen) {
    return 1;
  }

  bool running = true;

  SDL_Event event;
  while (running) {
    while (SDL_PollEvent(&event)) {
      if (event.type == SDL_QUIT) {
        running = false;
      }
    }
  }

  SDL_Quit();
  return 0;
}

当某些事件发生时，例如窗口关闭时，您可以将运行设置为false。

Answer 2

你已经把SDL_Quit（）;在你的计划的一开始。这就像放回0;在你所有的代码之前。它在读取该行时关闭。为了避免这种情况，你应该制作一个循环，当它按下窗口顶部的'x'时会中断。

窗口无法加载 - c ++ / SDL

2 个答案: