Question

如果已经提出这个问题，我很抱歉，但我现在已经研究了大约一个星期而且无法找到答案。

我遇到的问题是，当SDL_LoadBMP（）成功加载图像时，窗口根本不渲染图像，而是呈现完全黑屏。但是我确实知道正在加载某些东西（不仅仅是因为SDL_LoadBMP（）还没有返回错误，因为当我运行带有SDL_LoadBMP（）调用的程序注释掉时窗口保持完全白色。

如果有帮助我一直在写下the Lazyfoo tutorial located here.代码......

来自Main.cpp

int main(int argc, char* args[])
{
    //the surface that we will be applying an image on
    SDL_Surface* ImageSurface = NULL;

    //try to initalize SDL
    try
    {
        initSDL();
    }
    //if an error is caught
    catch (string Error)
    {
        //print out the error
        cout << "SDL error occurred! SDL Error: " << Error << endl;
        //return an error
        return -1;
    }

    //try loading an image on to the ImageSurface
    try
    {
        loadMedia(ImageSurface, "ImageTest.bmp");
    }
    //if an error is caught
    catch(string Error)
    {
        //print the error out
        cout << "SDL error occurred! SDL Error: " << Error << endl;
        //return an error
        SDL_Delay(6000);
        return -1;
    }
    //Apply Image surface to the main surface
    SDL_BlitSurface(ImageSurface, NULL, Surface, NULL);

    //upadte the surface of the main window
    SDL_UpdateWindowSurface(Window);

    //wait for 2 seconds (2000 miliseconds)
    SDL_Delay(10000);

    //close SDL
    close();

    //return
    return 0;
}

来自SDLBackend.cpp（我只会发布与图片加载过程相关的代码）

void loadMedia(SDL_Surface* surface, string path)
{
    cout << "Attempting to load an image!" << endl;
    //load the image at path into our surface
    surface = SDL_LoadBMP(path.c_str());
    //if there was an error in the loading procdure
    if(surface == NULL)
    {
        //make a string to store our error in
        string Error = SDL_GetError();
        //throw our error
        throw Error;
    }
    cout << "Successfully loaded an image!" << endl;
    cout << "Pushing surface into the Surface List" << endl;
    //Put the surface in to our list
    SurfaceList.push_back(surface);
    return;
}

我正在使用visual studio 2013进行编译，图像ImageTest.bmp与vcxproj文件位于同一目录中。

Answer 1

问题出在loadMedia()。已加载的曲面被分配给局部变量。您需要使用对指针的引用，

void loadMedia(SDL_Surface*& surface, string path)
{
    surface = SDL_LoadBMP(path.c_str());
}

或双指针（可能是首选，澄清意图），

void loadMedia(SDL_Surface** surface, string path)
{
    *surface = SDL_LoadBMP(path.c_str());
}

或者，您可以将其退回，甚至从SurfaceList.back()中提取。

SDL_LoadBMP（）成功，但窗口变为全黑

1 个答案: