Question

Using D3DXGetImageInfoFromFile() function gives me this:

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

Here is the piece of code that contains error:

// ...
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);

So, what is happening here? And when I type in numbers instead of Info->..., everything works fine…

Answer 1

You pass uninitialized pointer Info and when method tries to access you get the exception. What you need is the following:

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

Also, I’d recommend you handling result codes of any function that returns HRESULT. Like:

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

If you use DXUT.h then V() or V_RESULT macros are your best friends:

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;