c++ - D3DXGetImageInfoFromFile 函数

Question

使用 D3DXGetImageInfoFromFile() 函数给我这个:

SAMPLE.exe 中 0x004114d4 处的未处理异常:0xC0000005:访问冲突读取位置 0x00000000。

这是一段包含错误的代码:

// ...
WCHAR           *Path = L"./LIFE.bmp";
D3DXIMAGE_INFO      *Info;
IDirect3DSurface9   *Surface = NULL;
LPDIRECT3DDEVICE9   pd3dDevice;

// ...
D3DXGetImageInfoFromFile(Path, Info); // everything is fine here, unless i do the following:
pd3dDevice -> CreateOffscreenPlainSurface(Info->Width, Info->Height, Info->Format, D3DPOOL_SYSTEMMEM, &Surface, NULL);

那么，这里发生了什么？当我输入数字而不是 Info->... 时，一切正常...

Answer 1

您传递未初始化 指针信息，当方法尝试访问时您会得到异常。您需要的是:

D3DXIMAGE_INFO Info;
D3DXGetImageInfoFromFile(Path, &Info);
pd3dDevice->CreateOffscreenPlainSurface(Info.Width, Info.Height, Info.Format, D3DPOOL_SYSTEMMEM, &Surface, NULL);

此外，我建议您处理任何返回 HRESULT 的函数的结果代码。喜欢:

if (FAILED(D3DXGetImageInfoFromFile(Path, &Info))) {
  // print something, abort or whatever.
}

如果您使用 DXUT.h，那么 V() 或 V_RESULT 宏是您最好的 friend :

V(D3DXGetImageInfoFromFile(Path, &Info));

或

HRESULT hr;
V_RETURN(D3DXGetImageInfoFromFile(Path, &Info));
V_RETURN(pd3dDevice->CreateOffscreenPlainSurface(Info.Width, Info.Height, Info.Format, D3DPOOL_SYSTEMMEM, &Surface, NULL));
V_RETURN(...);
// ... lots of D3D calls.
return S_OK;