IDXGISwapChain::ResizeBuffers method (dxgi.h)
Changes the swap chain's back buffer size, format, and number of buffers. This should be called when the application window is resized.
HRESULT ResizeBuffers( UINT BufferCount, UINT Width, UINT Height, DXGI_FORMAT NewFormat, UINT SwapChainFlags );
The number of buffers in the swap chain (including all back and front buffers). This number can be different from the number of buffers with which you created the swap chain. This number can't be greater than DXGI_MAX_SWAP_CHAIN_BUFFERS. Set this number to zero to preserve the existing number of buffers in the swap chain. You can't specify less than two buffers for the flip presentation model.
The new width of the back buffer. If you specify zero, DXGI will use the width of the client area of the target window. You can't specify the width as zero if you called the IDXGIFactory2::CreateSwapChainForComposition method to create the swap chain for a composition surface.
The new height of the back buffer. If you specify zero, DXGI will use the height of the client area of the target window. You can't specify the height as zero if you called the IDXGIFactory2::CreateSwapChainForComposition method to create the swap chain for a composition surface.
A DXGI_FORMAT-typed value for the new format of the back buffer. Set this value to DXGI_FORMAT_UNKNOWN to preserve the existing format of the back buffer. The flip presentation model supports a more restricted set of formats than the bit-block transfer (bitblt) model.
A combination of DXGI_SWAP_CHAIN_FLAG-typed values that are combined by using a bitwise OR operation. The resulting value specifies options for swap-chain behavior.
Returns S_OK if successful; an error code otherwise. For a list of error codes, see DXGI_ERROR.
You can't resize a swap chain unless you release all outstanding references to its back buffers. You must release all of its direct and indirect references on the back buffers in order for ResizeBuffers to succeed.
Direct references are held by the application after it calls AddRef on a resource.
Indirect references are held by views to a resource, binding a view of the resource to a device context, a command list that used the resource, a command list that used a view to that resource, a command list that executed another command list that used the resource, and so on.
Before you call ResizeBuffers, ensure that the application releases all references (by calling the appropriate number of Release invocations) on the resources, any views to the resource, and any command lists that use either the resources or views, and ensure that neither the resource nor a view is still bound to a device context. You can use ID3D11DeviceContext::ClearState to ensure that all references are released. If a view is bound to a deferred context, you must discard the partially built command list as well (by calling ID3D11DeviceContext::ClearState, then ID3D11DeviceContext::FinishCommandList, then Release on the command list). After you call ResizeBuffers, you can re-query interfaces via IDXGISwapChain::GetBuffer.
For swap chains that you created with DXGI_SWAP_CHAIN_FLAG_GDI_COMPATIBLE, before you call ResizeBuffers, also call IDXGISurface1::ReleaseDC on the swap chain's back-buffer surface to ensure that you have no outstanding GDI device contexts (DCs) open.
We recommend that you call ResizeBuffers when a client window is resized (that is, when an application receives a WM_SIZE message).
The only difference between IDXGISwapChain::ResizeBuffers in Windows 8 versus Windows 7 is with flip presentation model swap chains that you create with the DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL or DXGI_SWAP_EFFECT_FLIP_DISCARD value set. In Windows 8, you must call ResizeBuffers to realize a transition between full-screen mode and windowed mode; otherwise, your next call to the IDXGISwapChain::Present method fails.