IDXGISwapChain::ResizeTarget method (dxgi.h)
Resizes the output target.
HRESULT ResizeTarget( [in] const DXGI_MODE_DESC *pNewTargetParameters );
Type: const DXGI_MODE_DESC*
A pointer to a DXGI_MODE_DESC structure that describes the mode, which specifies the new width, height, format, and refresh rate of the target. If the format is DXGI_FORMAT_UNKNOWN, ResizeTarget uses the existing format. We only recommend that you use DXGI_FORMAT_UNKNOWN when the swap chain is in full-screen mode as this method is not thread safe.
Returns a code that indicates success or failure. DXGI_STATUS_MODE_CHANGE_IN_PROGRESS is returned if a full-screen/windowed mode transition is occurring when this API is called. See DXGI_ERROR for additional DXGI error codes.
ResizeTarget resizes the target window when the swap chain is in windowed mode, and changes the display mode on the target output when the swap chain is in full-screen mode. Therefore, apps can call ResizeTarget to resize the target window (rather than a Microsoft Win32API such as SetWindowPos) without knowledge of the swap chain display mode.
If a Windows Store app calls ResizeTarget, it fails with DXGI_ERROR_NOT_CURRENTLY_AVAILABLE.
You cannot call ResizeTarget on a swap chain that you created with IDXGIFactory2::CreateSwapChainForComposition.
Apps must still call IDXGISwapChain::ResizeBuffers after they call ResizeTarget because only ResizeBuffers can change the back buffers. But, if those apps have implemented window resize processing to call ResizeBuffers, they don't need to explicitly call ResizeBuffers after they call ResizeTarget because the window resize processing will achieve what the app requires.