Resizing Window Glitch in C - c

Question

I need to make a WinAPI window in C. Not C++. In C, when I make the window, it has a problem with resizing. When I resize it to be bigger, it makes a black background with odd white patches in it. The only way to solve this is by making it the original size. It doesn't happen with C++. How can I fix this? It compiles without errors.
At normal size:
It displays correctly
Maximized:
It makes a strange effect.
Code:
wmain.h
#include <stdio.h>
#include <stdlib.h>
#include <Windows.h>
const wchar_t* szWndClassName = L"WindowClass"; const wchar_t* szWndName = L"Notepad";
int width = 600, height = 400;
HINSTANCE hInst; HWND hWnd;
WNDCLASS wc;
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
RECT rect;
int CenterWindow(HWND parent_window, int width, int height)
{
GetClientRect(parent_window, &rect);
rect.left = (rect.right / 2) - (width / 2);
rect.top = (rect.bottom / 2) - (height / 2);
return 0;
}
wmain.c
#include <stdio.h>
#include <stdlib.h>
#include <Windows.h>
#include "wmain.h"
#pragma warning (disable: 28251)
int WINAPI WinMain(HINSTANCE hThisInst, HINSTANCE hPrevInst, LPSTR lpszCMDArgs, int nCMDShow)
{
hInst = hThisInst;
wc.lpszClassName = szWndClassName;
wc.lpfnWndProc = WndProc;
wc.hInstance = hInst;
wc.hCursor = LoadCursor(wc.hInstance, L"IDC_ARROW");
wc.hIcon = LoadIcon(wc.hInstance, L"Resource Files/Images/Notepad.ico");
if (!RegisterClass(&wc))
{
MessageBox(NULL, L"RegisterClassW failed!", L"Error", MB_ICONERROR);
return 1;
}
CenterWindow(GetDesktopWindow(), width, height);
hWnd = CreateWindow(szWndClassName, szWndName, WS_OVERLAPPEDWINDOW, rect.left, rect.top, width, height, NULL, NULL, hInst, NULL);
if (!hWnd)
{
MessageBox(NULL, L"CreateWindowW failed!", L"Error", MB_ICONERROR);
return 2;
}
ShowWindow(hWnd, nCMDShow);
UpdateWindow(hWnd);
MSG msg;
while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT msg, WPARAM wp, LPARAM lp)
{
switch (msg)
{
case WM_CREATE:
break;
case WM_COMMAND:
switch (wp)
{
}
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hWnd, msg, wp, lp);
}
}
EDIT
To fix this, add this to your WNDCLASS properties:
wc.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);

Answer 1

Either set a window background in the WNDCLASS, or implement the WM_PAINT message to redraw the window.