C++ run a function in async and not block the ui - c++

Question

I have a small app that checks the dotnet framework, if it is not installed it will install it
Now when the application starts i want to popup a gif image with something like loading and in background check the framework and install.
the catch here is that it can not have any prerequisite to run the application
here is what i have till now
int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
_In_opt_ HINSTANCE hPrevInstance,
_In_ LPWSTR lpCmdLine,
_In_ int nCmdShow)
{
int exitCode = -1;
showPic(hInstance);
MessageBox(0L, L"Dotnet will installed", L"Alert", 0);
auto fut = std::async(std::launch::async, DoWork, hInstance, lpCmdLine);
fut.wait();
exitCode = fut.get();
return exitCode;
}
showPic()
void showPic(HINSTANCE hInstance)
{
loadImage(hInstance);
// create window
wnd = createWindow(hInstance);
SetWindowLong(wnd, GWL_STYLE, 0);
ShowWindow(wnd, SW_SHOW);
}
loadImage(HINSTANCE hInstance)
void loadImage(HINSTANCE hInstance)
{
imageDC = CreateCompatibleDC(NULL);
imageBmp = LoadBitmap(hInstance, MAKEINTRESOURCE(IDB_BITMAP1));
imageBmpOld = (HBITMAP)SelectObject(imageDC, imageBmp);
}
Now what is happening here is that the if i dont show the messagebox the picture does not load in the window, and still the window goes into not responding mode also i could not get it work with gif, only with bmp images
any help is appriciated
now since i wait for fut it is obvious that it will block the ui until it has the value, what is the workaround for that

Answer 1

This should be simple. Create the window, show it, call the thread, go to main message loop. When thread is done it will destroy the window.
struct T_data {
HWND hWnd;
HINSTANCE hInstance;
LPTSTR cmdline;
int exitCode;
};
DWORD WINAPI taking_too_long(LPVOID p) {
Sleep(2000); //wait at least 2 seconds!
T_data* data = reinterpret_cast<T_data*>(p);
auto fut = std::async(std::launch::async, DoWork, data->hInstance, data->lpCmdLine);
fut.wait();
data->exitCode = fut.get();
//make sure the window handles IDM_EXIT to close itself
PostMessage(data->hWnd, WM_COMMAND, IDM_EXIT, 0);
}
int APIENTRY wWinMain(HINSTANCE hInstance, HINSTANCE, LPTSTR lpCmdLine, int) {
T_data data;
data.exitCode = -1;
data.hWnd = hWnd;
data.hInstance = hInstance;
data.cmdline = lpCmdLine;
data.hWnd = showPic(hInstance);
CreateThread(NULL, 0, taking_too_long, &data, 0, NULL);
MSG msg;
while (GetMessage(&msg, NULL, 0, 0)) {
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return data.exitCode;
}