📄 8. 定时器.txt
字号:
MessageBox ( NULL, TEXT ("Program requires Windows NT!"),
szAppName, MB_ICONERROR) ;
return 0 ;
}
hwnd = CreateWindow ( szAppName, "Beeper2 Timer Demo",
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 ;
}
LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case WM_CREATE:
SetTimer (hwnd, ID_TIMER, 1000, TimerProc) ;
return 0 ;
case WM_DESTROY:
KillTimer (hwnd, ID_TIMER) ;
PostQuitMessage (0) ;
return 0 ;
}
return DefWindowProc (hwnd, message, wParam, lParam) ;
}
VOID CALLBACK TimerProc (HWND hwnd, UINT message, UINT iTimerID, DWORD dwTime)
{
static BOOL fFlipFlop = FALSE ;
HBRUSH hBrush ;
HDC hdc ;
RECT rc ;
MessageBeep (-1) ;
fFlipFlop = !fFlipFlop ;
GetClientRect (hwnd, &rc) ;
hdc = GetDC (hwnd) ;
hBrush = CreateSolidBrush (fFlipFlop ? RGB(255,0,0) : RGB(0,0,255)) ;
FillRect (hdc, &rc, hBrush) ;
ReleaseDC (hwnd, hdc) ;
DeleteObject (hBrush) ;
}
方法三
设定定时器的第三种方法类似于第二种方法，只是传递给SetTimer的hwnd参数被设定为NULL，并且第二个参数（通常为定时器ID）被忽略了，最后，此函数传回定时器ID：
iTimerID = SetTimer (NULL, 0, wMsecInterval, TimerProc) ;
如果没有可用的定时器，那么从SetTimer传回的iTimerID值将为NULL。
KillTimer的第一个参数（通常是窗口句柄）也必须为NULL，定时器ID必须是SetTimer的传回值：
KillTimer (NULL, iTimerID) ;
传递给TimerProc定时器函数的hwnd参数也必须是NULL。这种设定定时器的方法很少被使用。如果在您的程序在不同时刻有一系列的SetTimer呼叫，而又不希望追踪您已经用过了那些定时器ID，那么使用此方法是很方便的。
既然您已经知道了如何使用Windows定时器，就可以开始讨论一些有用的定时器程序了。
定时器用于时钟
时钟是定时器最明显的应用，因此让我们来看看两个时钟，一个数字时钟，一个模拟时钟。
建立数字时钟
程序8-3所示的DIGCLOCK程序，使用类似LED的7个显示方块显示了目前的时间。
程序8-3 DIGCLOCK
DIGCLOCK.C
/*----------------------------------------------------------------------------
DIGCLOCK.C -- Digital Clock
(c) Charles Petzold, 1998
----------------------------------------------------------------------------*/
#include <windows.h>
#define ID_TIMER 1
LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT ("DigClock") ;
HWND hwnd ;
MSG msg ;
WNDCLASS wndclass ;
wndclass.style = CS_HREDRAW | CS_VREDRAW ;
wndclass.lpfnWndProc = WndProc ;
wndclass.cbClsExtra = 0 ;
wndclass.cbWndExtra = 0 ;
wndclass.hInstance = hInstance ;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION) ;
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 ("Digital 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 DisplayDigit (HDC hdc, int iNumber)
{
static BOOL fSevenSegment [10][7] = {
1, 1, 1, 0, 1, 1, 1, // 0
0, 0, 1, 0, 0, 1, 0, // 1
1, 0, 1, 1, 1, 0, 1, // 2
1, 0, 1, 1, 0, 1, 1, // 3
0, 1, 1, 1, 0, 1, 0, // 4
1, 1, 0, 1, 0, 1, 1, // 5
1, 1, 0, 1, 1, 1, 1, // 6
1, 0, 1, 0, 0, 1, 0, // 7
1, 1, 1, 1, 1, 1, 1, // 8
1, 1, 1, 1, 0, 1, 1 } ; // 9
static POINT ptSegment [7][6] = {
7, 6, 11, 2, 31, 2, 35, 6, 31, 10, 11, 10,
6, 7, 10, 11, 10, 31, 6, 35, 2, 31, 2, 11,
36, 7, 40, 11, 40, 31, 36, 35, 32, 31, 32, 11,
7 , 36, 11, 32, 31, 32, 35, 36, 31, 40, 11, 40,
6 , 37, 10, 41, 10, 61, 6, 65, 2, 61, 2, 41,
36, 37, 40, 41, 40, 61, 36, 65, 32, 61, 32, 41,
7 , 66, 11, 62, 31, 62, 35, 66, 31, 70, 11, 70 } ;
int iSeg ;
for (iSeg = 0 ; iSeg < 7 ; iSeg++)
if (fSevenSegment [iNumber][iSeg])
Polygon (hdc, ptSegment [iSeg], 6) ;
}
void DisplayTwoDigits (HDC hdc, int iNumber, BOOL fSuppress)
{
if (!fSuppress || (iNumber / 10 != 0))
DisplayDigit (hdc, iNumber / 10) ;
OffsetWindowOrgEx (hdc, -42, 0, NULL) ;
DisplayDigit (hdc, iNumber % 10) ;
OffsetWindowOrgEx (hdc, -42, 0, NULL) ;
}
void DisplayColon (HDC hdc)
{
POINT ptColon [2][4] = { 2, 21, 6, 17, 10, 21, 6, 25,
2,51, 6, 47, 10, 51, 6, 55 } ;
Polygon (hdc, ptColon [0], 4) ;
Polygon (hdc, ptColon [1], 4) ;
OffsetWindowOrgEx (hdc, -12, 0, NULL) ;
}
void DisplayTime (HDC hdc, BOOL f24Hour, BOOL fSuppress)
{
SYSTEMTIME st ;
GetLocalTime (&st) ;
if (f24Hour)
DisplayTwoDigits (hdc, st.wHour, fSuppress) ;
else
DisplayTwoDigits (hdc, (st.wHour %= 12) ? st.wHour : 12, fSuppress) ;
DisplayColon (hdc) ;
DisplayTwoDigits (hdc, st.wMinute, FALSE) ;
DisplayColon (hdc) ;
DisplayTwoDigits (hdc, st.wSecond, FALSE) ;
}
LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam,LPARAM lParam)
{
static BOOL f24Hour, fSuppress ;
static HBRUSH hBrushRed ;
static int cxClient, cyClient ;
HDC hdc ;
PAINTSTRUCT ps ;
TCHAR szBuffer [2] ;
switch (message)
{
case WM_CREATE:
hBrushRed = CreateSolidBrush (RGB (255, 0, 0)) ;
SetTimer (hwnd, ID_TIMER, 1000, NULL) ;// fall through
case WM_SETTINGCHANGE:
GetLocaleInfo (LOCALE_USER_DEFAULT, LOCALE_ITIME, szBuffer, 2) ;
f24Hour = (szBuffer[0] == '1') ;
GetLocaleInfo (LOCALE_USER_DEFAULT, LOCALE_ITLZERO, szBuffer, 2) ;
fSuppress = (szBuffer[0] == '0') ;
InvalidateRect (hwnd, NULL, TRUE) ;
return 0 ;
case WM_SIZE:
cxClient = LOWORD (lParam) ;
cyClient = HIWORD (lParam) ;
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