《Windows程序设计》随书代码(SineWave.c)

/*-----------------------------------------
SINEWAVE.C -- Sine Wave Using Polyline
(c) Charles Petzold, 1998
-----------------------------------------*/

#include <windows.h>
#include <math.h>

#define NUM 1000 //定义了1000个点
#define TWOPI (2 * 3.14159) //TWOPI 等于 2pi

LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT ("SineWave") ;
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 ("Sine Wave Using Polyline"),
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)
{
static int cxClient, cyClient ;
HDC hdc ;
int i ;
PAINTSTRUCT ps ;
POINT apt [NUM] ;

switch (message)
{
case WM_SIZE: //获取客户区大小
cxClient = LOWORD (lParam) ;
cyClient = HIWORD (lParam) ;
return 0 ;

case WM_PAINT:
hdc = BeginPaint (hwnd, &ps) ;
//在中2份之一的高度处画条直线
MoveToEx (hdc, 0, cyClient / 2, NULL) ;
LineTo (hdc, cxClient, cyClient / 2) ;

for (i = 0 ; i < NUM ; i++)
{
apt[i].x = i * cxClient / NUM ; //根据数学公式得出的结果，如果看不懂，不要纠结在这个细节，还是一句话，弄懂流程就可以了，知道程序是怎么执行的顺序，这个简单的程序看不出来，但到后面加入子窗口之后，弄懂程序流程就很重要了
apt[i].y = (int) (cyClient / 2 * (1 - sin (TWOPI * i / NUM))) ;
}

Polyline (hdc, apt, NUM) ; //画一组连续的线
return 0 ;

case WM_DESTROY:
PostQuitMessage (0) ;
return 0 ;
}
return DefWindowProc (hwnd, message, wParam, lParam) ;
}