请教，windows程序设计第八周章的模拟时钟编译执行后为什么没有刻度？？？

[路口转弯]

这是全部代码，求高手指点。。。
#include <Windows.h>
#include <math.h>

#define ID_TIMER 1
#define TWOPI (2 * 3.14159)

LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam);

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT("Clock");
HWND hwnd;
MSG msg;
WNDCLASS wndclass;

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;
wndclass.lpszClassName = szAppName;
wndclass.lpszMenuName = NULL;
wndclass.style = CS_VREDRAW | CS_HREDRAW;

if (!RegisterClass(&wndclass))
{
return -1;
}

hwnd = CreateWindow(szAppName, TEXT("Analog Clock"),
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT,
CW_USEDEFAULT, CW_USEDEFAULT,
NULL, NULL,
hInstance, NULL);
if (NULL == hwnd)
{
return -1;
}

ShowWindow(hwnd, iCmdShow);
UpdateWindow(hwnd);

while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}

return msg.wParam;
}

void SetIsotropic(HDC hdc, int cxClient, int cyClinent)
{
SetMapMode(hdc, MM_ISOTROPIC);
SetWindowExtEx(hdc, 1000, 1000, NULL);
SetViewportExtEx(hdc, cxClient / 2, -cyClinent / 2, NULL);
SetViewportOrgEx(hdc, cxClient / 2, cyClinent / 2, NULL);
}

void RotatePoint(POINT pt[], int iNum, int iAngle)
{
int i;
POINT ptTemp;
for(i = 0; i < iNum; i++)
{
ptTemp.x = (int) (pt[i].x * cos(TWOPI * iAngle / 360) + pt[i].y * sin(TWOPI * iAngle / 360));
ptTemp.y = (int) (pt[i].y * cos(TWOPI * iAngle / 360) - pt[i].x * sin(TWOPI * iAngle / 360));
pt[i] = ptTemp;
}
}

void DrawClock(HDC hdc)
{
int iAngle;
POINT pt[3];

for(iAngle = 0; iAngle < 360; iAngle += 6)
{
pt[0].x = 0;
pt[0].y = 900;

RotatePoint(pt, 1, iAngle);

pt[2].x = pt[2].y = iAngle % 5 ? 33 : 100;

pt[0].x -= pt[2].x / 2;
pt[0].y -= pt[2].y / 2;

pt[1].x = pt[0].x + pt[1].x;
pt[1].y = pt[0].y + pt[1].y;

SelectObject(hdc, GetStockObject(BLACK_BRUSH));
Ellipse(hdc, pt[0].x, pt[0].y, pt[1].x, pt[1].y);
}
}

void DrawHands(HDC hdc, SYSTEMTIME * pst, BOOL fChange)
{
static POINT pt[3][5] = { 0, -150, 100, 0, 0, 600, -100, 0, 0, -150,
0, -200, 50, 0, 0, 800, -50, 0, 0, -200,
0, 0, 0, 0, 0, 0, 0, 0, 0, 800};

int i, iAngle[3];
POINT ptTemp[3][5];

iAngle[0] = (pst->wHour * 30) % 360 + pst->wMinute / 2;
iAngle[1] = pst->wMinute * 6;
iAngle[2] = pst->wSecond * 6;

memcpy(ptTemp, pt, sizeof(pt));

for(i = fChange ? 0 : 2; i < 3; i++)
{
RotatePoint(ptTemp[i], 5, iAngle[i]);
Polyline(hdc, ptTemp[i], 5);
}
}


LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{

static int cxClient, cyClient;
static SYSTEMTIME stPrevious;
BOOL fChange;
HDC hdc;
PAINTSTRUCT ps;
SYSTEMTIME st;

switch(message)
{
case WM_CREATE:
SetTimer(hwnd, ID_TIMER, 1000, NULL);
GetLocalTime(&st);
stPrevious = st;
break;
case WM_SIZE:
cxClient = LOWORD(lParam);
cyClient = HIWORD(lParam);
break;
case WM_TIMER:
GetLocalTime(&st);
fChange = st.wHour != stPrevious.wHour || st.wMinute != stPrevious.wMinute;

hdc = GetDC(hwnd);

SetIsotropic(hdc, cxClient, cyClient);

SelectObject(hdc, GetStockObject(WHITE_PEN));
DrawHands(hdc, &stPrevious, fChange);

SelectObject(hdc, GetStockObject(BLACK_PEN));
DrawHands(hdc, &st, TRUE);

ReleaseDC(hwnd, hdc);

stPrevious = st;
break;
case WM_PAINT:
hdc = BeginPaint(hwnd, &ps);

SetIsotropic(hdc, cxClient, cyClient);
DrawClock(hdc);
DrawHands(hdc, &stPrevious, TRUE);
EndPaint(hwnd, &ps);
break;
case WM_DESTROY:
KillTimer(hwnd, ID_TIMER);
PostQuitMessage(0);
break;
default:
return DefWindowProc(hwnd, message, wParam, lParam);
}

return 0;
}

[路口转弯]

这是执行后的结果图片

[Codning]

draw clock 里面应该是 pt[1].x=pt[0].x+pt[2].x; pt[1].y=pt[0].y+pt[2].y;