부모윈도우가 차일드 영역을 클리핑 (WS_CLIPCHILDREN)

#include <windows.h>

LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
HINSTANCE g_hInst;
LPSTR lpszClass="ClipChildren";

int APIENTRY WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance
         ,LPSTR lpszCmdParam,int nCmdShow)
{
    HWND hWnd;
    MSG Message;
    WNDCLASS WndClass;
    g_hInst=hInstance;
    
    WndClass.cbClsExtra=0;
    WndClass.cbWndExtra=0;
    WndClass.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH);
    WndClass.hCursor=LoadCursor(NULL,IDC_ARROW);
    WndClass.hIcon=LoadIcon(NULL,IDI_APPLICATION);
    WndClass.hInstance=hInstance;
    WndClass.lpfnWndProc=(WNDPROC)WndProc;
    WndClass.lpszClassName=lpszClass;
    WndClass.lpszMenuName=NULL;
    WndClass.style=CS_HREDRAW | CS_VREDRAW;
    RegisterClass(&WndClass);

    hWnd=CreateWindow(lpszClass,lpszClass,
        WS_OVERLAPPEDWINDOW | WS_CLIPCHILDREN,    // WS_CLIPCHILDREN 부모윈도우가 차일드 영역을 클리핑 하도록 하는것
        CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,
        NULL,(HMENU)NULL,hInstance,NULL);
    ShowWindow(hWnd,nCmdShow);
    
    while(GetMessage(&Message,0,0,0)) {
        TranslateMessage(&Message);
        DispatchMessage(&Message);
    }
    return Message.wParam;
}

#define ID_SCRRED 100
#define ID_SCRGREEN 101
#define ID_SCRBLUE 102
HWND hRed,hGreen,hBlue;
int Red,Green,Blue;

LRESULT CALLBACK WndProc(HWND hWnd,UINT iMessage,WPARAM wParam,LPARAM lParam)
{
    HDC hdc;
    PAINTSTRUCT ps;
    HBRUSH MyBrush, OldBrush;
    int TempPos;
    switch(iMessage) {
    case WM_LBUTTONDOWN:            // 왼쪽 버튼 선택시
        LockWindowUpdate(hWnd);
        return 0;
    case WM_RBUTTONDOWN:
        LockWindowUpdate(NULL);
        return 0;
    case WM_CREATE:
        // 스크롤 바 생성
        hRed=CreateWindow("scrollbar",NULL,WS_CHILD | WS_VISIBLE | SBS_HORZ,
            10,10,200,20,hWnd,(HMENU)ID_SCRRED,g_hInst,NULL);
        hGreen=CreateWindow("scrollbar",NULL,WS_CHILD | WS_VISIBLE | SBS_HORZ,
            10,40,200,20,hWnd,(HMENU)ID_SCRGREEN,g_hInst,NULL);
        hBlue=CreateWindow("scrollbar",NULL,WS_CHILD | WS_VISIBLE | SBS_HORZ,
            10,70,200,20,hWnd,(HMENU)ID_SCRBLUE,g_hInst,NULL);

        SetScrollRange(hRed,SB_CTL,0,255,TRUE);        // 스크롤바의 range설정
        SetScrollPos(hRed,SB_CTL,0,TRUE);            // 스크롤바의 기본값 설정
        SetScrollRange(hGreen,SB_CTL,0,255,TRUE);
        SetScrollPos(hGreen,SB_CTL,0,TRUE);
        SetScrollRange(hBlue,SB_CTL,0,255,TRUE);
        SetScrollPos(hBlue,SB_CTL,0,TRUE);
        return 0;
    case WM_HSCROLL:
        if ((HWND)lParam == hRed) TempPos = Red;
        if ((HWND)lParam == hGreen) TempPos = Green;
        if ((HWND)lParam == hBlue) TempPos = Blue;
        switch (LOWORD(wParam)) {
        case SB_LINELEFT:
            TempPos=max(0,TempPos-1);
            break;
        case SB_LINERIGHT:
            TempPos=min(255,TempPos+1);
            break;
        case SB_PAGELEFT:
            TempPos=max(0,TempPos-10);
            break;
        case SB_PAGERIGHT:
            TempPos=min(255,TempPos+10);
            break;
        case SB_THUMBTRACK:
            TempPos=HIWORD(wParam);
            break;
        }
        if ((HWND)lParam == hRed) Red=TempPos;
        if ((HWND)lParam == hGreen) Green=TempPos;
        if ((HWND)lParam == hBlue) Blue=TempPos;
        SetScrollPos((HWND)lParam,SB_CTL,TempPos,TRUE);
        InvalidateRect(hWnd,NULL,FALSE);
        return 0;
    case WM_PAINT:
        hdc=BeginPaint(hWnd,&ps);
        MyBrush=CreateSolidBrush(RGB(Red,Green,Blue));
        OldBrush=(HBRUSH)SelectObject(hdc,MyBrush);
        Rectangle(hdc,10,100,210,200);
        SelectObject(hdc,OldBrush);
        DeleteObject(MyBrush);
        EndPaint(hWnd,&ps);
        return 0;
    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }
    return(DefWindowProc(hWnd,iMessage,wParam,lParam));
}