自己的不足
今天看了windows程序第8章的 DigClock程序，令我感叹不已呀。是一个数字时种，如下：
让我明白了原先我们去的那种老式数字电子表的数字是怎样显示的，那个要显示0-9的数字，通过变换方块的多少来表示0-9的方法，记得以前我也研究过，但是始终没想到作者用那么短的代码实现了。
唉，哪位大大能告诉我，为什么作者能用那么短的几个函数把这些数字控制自如，这个需要什么技术？数据结构？我想不是。。。。
/*-----------------------------------------
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) ;
return 0 ;
case WM_TIMER:
InvalidateRect (hwnd, NULL, TRUE) ;
return 0 ;
case WM_PAINT:
hdc = BeginPaint (hwnd, &ps) ;
SetMapMode (hdc, MM_ISOTROPIC) ;
SetWindowExtEx (hdc, 276, 72, NULL) ;
SetViewportExtEx (hdc, cxClient, cyClient, NULL) ;
SetWindowOrgEx (hdc, 138, 36, NULL) ;
SetViewportOrgEx (hdc, cxClient / 2, cyClient / 2, NULL) ;
SelectObject (hdc, GetStockObject (NULL_PEN)) ;
SelectObject (hdc, hBrushRed) ;
DisplayTime (hdc, f24Hour, fSuppress) ;
EndPaint (hwnd, &ps) ;
return 0 ;
case WM_DESTROY:
KillTimer (hwnd, ID_TIMER) ;
DeleteObject (hBrushRed) ;
PostQuitMessage (0) ;
return 0 ;
}
return DefWindowProc (hwnd, message, wParam, lParam) ;
}