마우스 입력 (Mouse Input)

#include <windows.h>

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

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 | CS_DBLCLKS;
    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;
}

LRESULT CALLBACK WndProc(HWND hWnd,UINT iMessage,WPARAM wParam,LPARAM lParam)
{
    HDC hdc;
    static int x;
    static int y;
    static BOOL bnowDraw=FALSE;
    switch(iMessage) {
    case WM_LBUTTONDOWN:        // Clicked Mouse Left button
        x=LOWORD(lParam);
        y=HIWORD(lParam);
        bnowDraw=TRUE;
        return 0;
    case WM_MOUSEMOVE:            // Clicked option bNowDraw enable case
        if (bnowDraw==TRUE) {    // do x y save to linked list
            hdc=GetDC(hWnd);
            MoveToEx(hdc,x,y,NULL);
            x=LOWORD(lParam);
            y=HIWORD(lParam);
            LineTo(hdc,x,y);
            ReleaseDC(hWnd,hdc);
        }
        return 0;
    case WM_LBUTTONUP:            // Unclicked Mouse Left button
        bnowDraw=FALSE;
        return 0;
    case WM_LBUTTONDBLCLK:        // Double Clicked Mouse left button
        InvalidateRect(hWnd, NULL, TRUE);
        return 0;
    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }
    return(DefWindowProc(hWnd,iMessage,wParam,lParam));
}