윈도우 크기, 사이즈 조정 (WM_SIZE)

#include <windows.h>

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

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,
        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_LISTBOX 100
char Items[][15]={"Apple","Orange","Melon","Grape","Strawberry"};
HWND hList;
LRESULT CALLBACK WndProc(HWND hWnd,UINT iMessage,WPARAM wParam,LPARAM lParam)
{
    int i;
    RECT crt;

    switch(iMessage) {
    case WM_CREATE:
        hList=CreateWindow("listbox",NULL,WS_CHILD | WS_VISIBLE | LBS_NOINTEGRALHEIGHT,
            0,0,0,0,hWnd,(HMENU)ID_LISTBOX,g_hInst,NULL);        // Create Listbox
        for (i=0;i<5;i++)
            SendMessage(hList,LB_ADDSTRING,0,(LPARAM)Items[i]);    // Add string
        return 0;
    case WM_SIZE:
        GetClientRect(hWnd, &crt);        // Window의 top, left, bottom, right 값을 얻기
        MoveWindow(hList, crt.left, crt.top, crt.right, crt.bottom, TRUE);    // listbox의 size를 change
        return 0;
    case WM_SIZING:        // Window의 size를 변경하고 있을때
    /*
    Parameters
        wParam
        Specifies which edge of the window is being sized. This parameter can be one of the following values.
            WMSZ_BOTTOM
                Bottom edge
            WMSZ_BOTTOMLEFT
                Bottom-left corner
            WMSZ_BOTTOMRIGHT
                Bottom-right corner
            WMSZ_LEFT
                Left edge
            WMSZ_RIGHT
                Right edge
            WMSZ_TOP
                Top edge
            WMSZ_TOPLEFT
                Top-left corner
            WMSZ_TOPRIGHT
                Top-right corner
        lParam
            Pointer to a RECT structure with the screen coordinates of the drag rectangle. To change the size or position of the drag rectangle, an application must change the members of this structure.
        
        Return Value
            An application should return TRUE if it processes this message.
        */

        // 왼쪽변을 드래그 하고 있을 경우
        // 50씩 윈도우를 축소, 확대 한다.
        if (wParam==WMSZ_LEFT)
        ((RECT *)lParam)->left = ((RECT *)lParam)->left / 50 * 50;
        return TRUE;
    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }
    return(DefWindowProc(hWnd,iMessage,wParam,lParam));
}