I had a similiar issue once, and it turned out I was doing windowed mode wrong in terms of calculating the window size to fit the backbuffer
size etc., resulting in a vaguely stretched display that was hard to notice for a long while.. Maybe you could check your window+DirectX
I was going to say the same thing. You want to make sure that the client area of your window is the same size as your D3D backbuffer,
otherwise you'll get really crappy scaling when the backbuffer is blit onto the window. You can use something like this:
RECT windowRect; SetRect(&windowRect, 0, 0, backBufferWidth, backBufferHeight); BOOL isMenu = (GetMenu(hwnd) != nullptr); if(AdjustWindowRectEx(&windowRect, style, isMenu, exStyle) == 0) DoErrorHandling(); if(SetWindowPos(hwnd, HWND_NOTOPMOST, 0, 0, windowRect.right - windowRect.left, windowRect.bottom - windowRect.top, SWP_NOMOVE) == 0) DoErrorHandling();See the docs for AdjustWindowRectEx for more details.