Fix game window resolution when resizing during fullscreen on Windows

#3699

Source/Engine/GraphicsDevice/DirectX/DX11/GPUSwapChainDX11.cpp

@@ -162,11 +162,8 @@ void GPUSwapChainDX11::Present(bool vsync)
 
 bool GPUSwapChainDX11::Resize(int32 width, int32 height)
 {
-    // Check if size won't change
     if (width == _width && height == _height)
-    {
         return false;
-    }
 
     _device->WaitForGPU();
     GPUDeviceLock lock(_device);
@@ -174,6 +171,10 @@ bool GPUSwapChainDX11::Resize(int32 width, int32 height)
     _allowTearing = _device->_allowTearing;
 #endif
     _format = GPU_BACK_BUFFER_PIXEL_FORMAT;
+    if (_memoryUsage != 0)
+    {
+        PROFILE_MEM_DEC(Graphics, _memoryUsage);
+    }
 
 #if PLATFORM_WINDOWS
     DXGI_SWAP_CHAIN_DESC swapChainDesc;

Source/Engine/Platform/Windows/WindowsWindow.cpp

@@ -409,6 +409,17 @@ void WindowsWindow::SetClientBounds(const Rectangle& clientArea)
     int32 width = (int32)clientArea.GetWidth();
     int32 height = (int32)clientArea.GetHeight();
 
+    // Resize during fullscreen
+    if (changeSize && _swapChain && _swapChain->IsFullscreen())
+    {
+        // Go out fullscreen, resize, and then go back in
+        _swapChain->SetFullscreen(false);
+        _clientSize = clientArea.Size;
+        OnResize(width, height);
+        _swapChain->SetFullscreen(true);
+        return;
+    }
+
     if (changeSize)
     {
         _clientSize = clientArea.Size;