//通过移动坐标原点来实现正弦曲线，可以减少数组元素的移动
//但要开辟2*NUM空间的数组。
#include <windows.h>
#include <math.h>
#define ID_TIMER 1
#define NUM 1000
#define STEP 10//每次移动的步长
#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 ("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 ;
static POINT apt [2*NUM] ;
static HPEN hPen1,hPen2;
static int step;
switch (message)
{
case WM_SIZE:
cxClient = LOWORD(lParam);
cyClient = HIWORD(lParam);
for(i = 0; i < 2 * NUM; i++)
{
apt[i].x = (int)(i * cxClient / NUM);
apt[i].y = (int) (cyClient * (1 - sin(TWOPI * i / NUM)) / 2);
}
return 0;
case WM_CREATE:
hPen1 = CreatePen(PS_SOLID,4,RGB(255,0,0));
hPen2 = CreatePen(PS_SOLID,2,RGB(0,255,0));
SetTimer(hwnd,ID_TIMER,100,NULL);
return 0;
case WM_TIMER:
step= (step+STEP) % NUM;
InvalidateRect(hwnd,NULL,true);
UpdateWindow(hwnd);
return 0;
case WM_PAINT:
hdc = BeginPaint(hwnd,&ps);
SetViewportOrgEx(hdc,-step*cxClient/NUM,0,NULL);
SelectObject(hdc,hPen1);
MoveToEx(hdc,-step*cxClient/NUM,cyClient/2,NULL);
LineTo(hdc,cxClient+step*cxClient/NUM,cyClient/2);
SelectObject(hdc,hPen2);
Polyline (hdc, apt+step, NUM) ;
EndPaint(hwnd,&ps);
return 0;
case WM_DESTROY:
PostQuitMessage(0);
KillTimer(hwnd,ID_TIMER);
DeleteObject(hPen1);
DeleteObject(hPen2);
return 0; }
return DefWindowProc(hwnd,message,wParam,lParam);
}
