Unable to resize win 32 window - c++

Question

I'm trying to learn how to create a window in win 32. This is as far as I have got with it. The problem I'm facing is I'm unable to create a window that can be resized by the user. I'm hoping that someone could help me solve this newbie problem.
LRESULT CALLBACK WindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
std::string msg = "";
UINT width = 0;
UINT height = 0;
switch(uMsg)
{
case WM_SIZE:
width = LOWORD(lParam);
height = HIWORD(lParam);
if(width<(height*600)/800) SetWindowPos(hWnd, NULL, 0, 0, width, height, SWP_NOMOVE|SWPNOZORDER);
return true;
case WM_SIZING:
width = LOWORD(lParam);
height = HIWORD(lParam);
if(width<(height*600)/800) SetWindowPos(hWnd, NULL, 0, 0, width, height, SWP_NOMOVE|SWPNOZORDER);
return true;
case WM_DESTROY:
PostQuitMessage(0);
return true;
default:
return DefWindowProc(hWnd, uMsg, wParam, lParam);
}
}
int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PWSTR lpCmdLine, INT nCmdShow)
{
WNDCLASSEX wnd = {0};
wnd.lpszClassName = "WindowLearn";
wnd.hInstance = hInstance;
wnd.lpfnWndProc = windowProc;
wnd.cbSize = sizeof(WNDCLASSEX);
wnd.style = CS_HREDRAW | CS_VREDRAW;
RegisterClassEx(&wnd);
HWND hWnd = CreateWindowEx(NULL, "WindowLearn", "WindowLearnChild", WS_THICKFRAME | WS_SYSMENU | WS_MINIMIZEBOX | WS_MAXIMIZEBOX, 0, 0, 800, 600, NULL, NULL, hInstance, NULL);
ShowWindow(hWnd, nCmdShow);
MSG msg = {0};
float pTime = 0.0f;
BOOL result;
while(msg.message != WM_QUIT)
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
Window gets created OK, but with this when I try to resize the window the window gets stuck to the mouse.

Answer 1

It appears that you want to to idle processing, meaning having some tasks done for your directX application when no event are present in the event loop.
There are 2 different ways of doing that:
dedicate a separate thread for background processing. It adds the complexity of multiprocessing, but allows to do all the processing as a single piece of code, and let the system affect time slices to the event loop and the background processing.
use a modified event loop that does chunks of background processing when no event are present. PeekMessage is the key here:
...
MSG msg = {0};
for (;;)
{
if (PeekMessage(&msg, NULL, 0, 0, 0, 0) {
if (! GetMessage(&msg, NULL, 0, 0, 0)) break; // msg is WM_QUIT
TranslateMessage(&msg);
DispatchMessage(&msg);
}
else {
// do some idle processing for a short time
// no event will be processing during that
...
}
}
The nice point is that you do not need any multi-threading, but you have to explicitely split you backgroung processing in short time slices.