D3DXGetImageInfoFromFile函数

Question

使用D3DXGetImageInfoFromFile()函数给我这个：

Unhandled exception at 0x004114d4 in SAMPLE.exe: 0xC0000005: Access violation reading location 0x00000000.

以下是包含错误的代码：

// ...
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Info，当方法尝试访问时，您将获得异常。您需要的是以下内容：

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

另外，我建议您处理返回HRESULT的任何函数的结果代码。像：

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

如果你使用 DXUT.h ，那么V()或V_RESULT宏是你最好的朋友：

V(D3DXGetImageInfoFromFile(Path, &Info));

OR

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;

Answer 2

您可能需要转义图像路径中的反斜杠：

std::wstring wsPath = L"C:\\wood.bmp";