A way to listen window mode changes WndProc

Question

I'd like to refresh my swap chain when my game switches from windowed to fullscreen and vice versa, for the moment I only found uMsg == WM_SIZE which but it's not optimal, fullscreen to borderless doesn't work unfortunately.... Is there another message ? Thanks

Answer 1

For "fullscreen" vs. "windowed" handling using DXGI, there are two basic approaches:

1. Let DXGI do it for you via DXGI_SWAP_CHAIN_FLAG_ALLOW_MODE_SWITCH.

2. Use the flag DXGI_MWA_NO_WINDOW_CHANGES and handle it yourself. You in fact do use WM_SIZE to determine the changes. You may also want to use DXGI_MWA_NO_ALT_ENTER and handle the ALT+ENTER shortcut in your WndProc.

See Microsoft Docs: DirectX Graphics Infrastructure (DXGI) Best Practices.

For windowed mode, a challenge with WM_SIZE is that as the 'rubberband' rectangle is adjusted you get a lot of these messages, and resizing the backbuffer is not that fast. One solution here is to use WM_ENTERSIZEMOVE and WM_EXITSIZEMOVE so you can pause the resizing until it's completed.

See GitHub a detailed WndProc implementation.

One final point: There are actually several definitions for 'fullscreen'. See this blog post.