源代码如下:
#include <windows.h>
#include <math.h>
#define ID_TIMER 1
#define TWOPI (2 * 3.14159)
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT("Clock");
HWND hwnd;
WNDCLASS wndclass;
MSG msg;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = WndProc;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = NULL ;
wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);
wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = szAppName;
if(!RegisterClass(&wndclass))
{
MessageBox(NULL, TEXT ("Program requires Windows NT!"),
szAppName, MB_ICONERROR);
return 0;
}
hwnd = CreateWindow(szAppName, TEXT("Analog Clock"),
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT,
CW_USEDEFAULT, CW_USEDEFAULT,
NULL, NULL, hInstance, NULL
);
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 cyClient)
{
SetMapMode(hdc, MM_ISOTROPIC);
SetWindowExtEx(hdc, 1000, 1000, NULL);
SetViewportExtEx(hdc, cxClient / 2, -cyClient / 2, NULL);
SetViewportOrgEx(hdc, cxClient / 2, cyClient / 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); //Rotate clockwise in 6 degrees
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[2].x;
pt[1].y = pt[0].y + pt[2].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;
return 0;
case WM_SIZE:
cxClient = LOWORD(lParam);
cyClient = HIWORD(lParam);
return 0;
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;
return 0;
case WM_PAINT:
hdc = BeginPaint(hwnd, &ps);
SetIsotropic(hdc, cxClient, cyClient);
DrawClock(hdc);
DrawHands(hdc, &stPrevious, TRUE);
EndPaint(hwnd, &ps);
return 0;
case WM_DESTROY:
KillTimer(hwnd, ID_TIMER);
PostQuitMessage(0);
return 0;
}
return DefWindowProc(hwnd, message, wParam, lParam);
}
结果如下图: