Question

所以我正在制作一个我想要使用资产管理器的图形应用程序（游戏）。对于本课程，我决定使用Singleton Design。所以在我的main.cpp中我会加载像......

ASSET_MANAGER.LoadImage("res/graphics/background.png", "background");

以上是上述行中使用的宏/方法的含义。这是一种代码混搭，我必须让事情变得更简单，而不是在这里粘贴几百行代码。

assetmanager.h

#define ASSET_MANAGER AssetManager::GetAssetManager()
#define DEBUG

class AssetManager {
public:
static AssetManager &GetAssetManager();

//-----------------------------------------------------------------------------
// Purpose: Load a new image for the game to use. This function will store an
//          instance of the asset in memory (in a hash map corresponding with
//          the data type provided.
//
// param file: The location on disk of the asset
// param key: The string you use to receive this asset (defaults to the path str)
//-----------------------------------------------------------------------------
bool LoadImage(const char *file, const char *key = "");

//-----------------------------------------------------------------------------
// Purpose: Returns the image
//
// param key: The string used to store the asset in memory
//-----------------------------------------------------------------------------
ALLEGRO_BITMAP *GetImage(const char *key);

//-----------------------------------------------------------------------------
// Purpose: Destroys an asset that is presumably no longer needed by the game.
//          This function is good for performance so that you don't use more
//          RAM than you need to.
//
// param key: The string you use to receive this asset (defaults to the path str)
//-----------------------------------------------------------------------------
void DiscardImage(const char *key);
private:
    AssetManager();

    ~AssetManager();

    std::map<const char *, std::shared_ptr<ALLEGRO_BITMAP>> _ImageMap;
}

assetmanager.cpp

AssetManager &AssetManager::GetAssetManager() {
    static AssetManager instance;
    return instance;
}

bool AssetManager::LoadImage(const char *file, const char *key) {
    key = key == "" ? file : key;
    std::shared_ptr<ALLEGRO_BITMAP> x(al_load_bitmap(file), al_destroy_bitmap);
    if (!x) {
        fprintf(stderr, "Failed to load %s\n", file);
        return false;
    }
#ifdef DEBUG
    printf("DEBUG: Loaded %s\n", key); //debug
#endif // DEBUG
    _ImageMap.insert(std::pair<const char *, std::shared_ptr<ALLEGRO_BITMAP>>(key, x));
    return true;
}

ALLEGRO_BITMAP *AssetManager::GetImage(const char *key) {
    return _ImageMap.find(key) != _ImageMap.end() ? _ImageMap.at(key).get() : nullptr;
}

void AssetManager::DiscardImage(const char *key) {
    _ImageMap.erase(key);
#ifdef DEBUG
    printf("DEBUG: Discarded %s\n", key); //debug
#endif // DEBUG
}

这个类只适用于我初始化资产管理器的类，而我期望它可以在我调用ASSET_MANAGER的任何地方工作。它编译得很好，当我尝试在不同的类中使用管理器并将其传递给allegro函数时它只会崩溃，因为它返回的是null而不是正确的allegro数据类型。我对此不了解什么？

Answer 1

地图中的Char *存储位置，而不是使程序认为它为空的数据。

全局访问单身人士的数据

1 个答案: