I want to resize a screen captured using the Desktop Duplication API in SharpDX. I am using the Screen Capture sample code from the SharpDX Samples repository, relevant port
You need to take your original source surface in GPU memory and Draw() it on to a smaller surface. This involves simple vector/pixel shaders, which some folks with simple needs would rather bypass.
I would look to see if someone made a sprite lib for sharpdx. It should be a common "thing"...or using Direct2D (which is much more fun). Since D2D is just a user-mode library over D3D, it interops with D3D very easily.
I've never used SharpDx, but fFrom memory you would do something like this:
1.) Create an ID2D1Device, wrapping your existing DXGI Device (make sure your dxgi device creation flag has D3D11_CREATE_DEVICE_BGRA_SUPPORT)
2.) Get the ID2D1DeviceContext from your ID2D1Device
3.) Wrap your source and destination DXGI surfaces into D2D bitmaps with ID2D1DeviceContext::CreateBitmapFromDxgiSurface
4.) ID2D1DeviceContext::SetTarget of your destination surface
5.) BeginDraw, ID2D1DeviceContext::DrawBitmap, passing your source D2D bitmap. EndDraw
6.) Save your destination