in the normal d3d application, when we resize the window or drag the window, it will block the main thread.

if it is a online-game, it will block the logic.

so i want to find a method to resolve the problem.

in my option, multi thread is a proper resolution,

so i create the window( CreateWindowEx ) in the special thread, and call PeekMessage in that thread, like this:

UINT GameWindow::Exec()
        {

            HINSTANCE hInst = 0;

            hInst = (HINSTANCE)::GetModuleHandle(NULL);

            // register window
            WNDCLASSEX wc = {0};

            wc.cbSize        = sizeof(WNDCLASSEX);
            wc.style         = CS_OWNDC | CS_HREDRAW | CS_VREDRAW;
            wc.lpfnWndProc   = StaticClientWndProc;
            wc.cbClsExtra    = 0;
            wc.cbWndExtra    = 0;
            wc.hInstance     = hInst;
            wc.hIcon         = LoadIcon(0, IDI_WINLOGO);
            wc.hCursor       = LoadCursor(0, IDC_ARROW);
            //wc.hbrBackground = (HBRUSH)GetStockObject(NULL_BRUSH);
            wc.hbrBackground = NULL;
            wc.lpszMenuName  = 0;
            wc.lpszClassName = L"xxxxxMainWindow";

            if( !RegisterClassExW(&wc) )
            {
                LogError( _T("Can't Register Window Class:") _T("HikariMainWindow") );
                LogError( _T("Last Error:"), System::Error::GetErrorDesc() );

                return false;
            }

            DWORD WindowStyle;

            WindowStyle = WS_OVERLAPPEDWINDOW;

            // Create Window
            m_WndID = CreateWindowExW(
                WS_EX_APPWINDOW,
                L"MainWindow",
                Detail::UTF8ToWCHAR(m_strTitle).CStr(),
                WindowStyle,
                CW_USEDEFAULT, CW_USEDEFAULT, m_SizeX, m_SizeY,
                NULL,
                NULL,
                hInst,
                NULL );
               
            // ...... 	

            m_CreateWindowEvent.Trigger();

            MSG msg = {0};

            do
            {
                while( PeekMessage( &msg, 0, 0, 0, PM_REMOVE ) )
                {
                    TranslateMessage( &msg );
                    DispatchMessage( &msg );
                }
            }while( !IsRequestExit() );            

            return 0;
        }

so the WndProc will called in this thread, in this function, i send all the parameters to main thread.

and in main thread, i open the message queue, process all the messages.

        LRESULT GameWindow::StaticClientWndProc( HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam )
        {
            X_ASSERT( g_WindowsMessageDisptacher );

            SendWindowsEventImpl(
                true,
                g_WindowsMessageDisptacher,
                WindowsMessageCommandDispatcher::ALIGN_SIZE,
                HWND, hWnd, hwnd,
                UINT, message, msg,
                WPARAM, w, wParam,
                LPARAM, h, lParam
            );	

            return ::DefWindowProc( hwnd, msg, wParam, lParam );
        }

in the main thread.

        void GameWindow::ProcessGameWindowEvent( HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam )
        {
            switch( msg )
            {
            case WM_DESTROY:
                ::PostQuitMessage(0);
                break;
            case WM_CLOSE:
                m_bRequestExit = true;
                g_GameEngine->RequestQuit();
                break;
            case WM_SIZE:
                if( g_GameEngine && wParam == SIZE_RESTORED )
                {
                   // g_GameEngine->OnGameWindowResize( LOWORD(lParam), HIWORD(lParam) );
                }

                break;
            }
        }

it works well if i just drag the window, the main thread and its main loop is not blocked.

the question is when i resize the window, there is a render error when i call

Direct3D9: (ERROR) :BitBlt or StretchBlt failed in Present

if i ignore this error, it will work well in next frame.

so i want to know how to avoid this error when i create window in individual thread.

is there any articles or topics?

my render work is also doing in the individual thread.

According to the documentation, all D3D9 API calls should be made on the same thread where your window is created/updated

if i create the window and process windows message in the render thread, it will block rendering too, and then ,render thread will block the main thread, because main thread will wait render thread every frame.