cliprgn.c

C#一个实例源代码

/*--------------------------------------------------
   CLOVER.C -- Clover Drawing Program Using Regions
               (c) Charles Petzold, 1998
  --------------------------------------------------*/

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

#define TWO_PI (2.0 * 3.14159)

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

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
{
     static TCHAR szAppName[] = TEXT ("ClipRgn") ;
     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 ("This program requires Windows NT!"),
                      szAppName, MB_ICONERROR) ;
          return 0 ;
     }
     
     hwnd = CreateWindow (szAppName, TEXT ("Clip Region"),
                          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 ;
}

BOOL DrawLines(HDC hdc,double fAngle,double fRadius)
{
	for (fAngle = 0.0 ; fAngle < TWO_PI ; fAngle += TWO_PI / 360)
          {
               MoveToEx (hdc, 0, 0, NULL) ;
               LineTo (hdc, (int) ( fRadius * cos (fAngle) + 0.5),
                            (int) (-fRadius * sin (fAngle) + 0.5)) ;
          }
	return TRUE;
}

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
     static HRGN hClipRgn ;
     static int  cxClient, cyClient ;
     double      fAngle=0, fRadius ;
     HCURSOR     hCursor ;
     HDC         hdc ;
     HRGN        hTempRgn[6] ;
     int         i ;
     PAINTSTRUCT ps ;
     
     switch (message)
     {
     case WM_SIZE:
          cxClient = LOWORD (lParam) ;
          cyClient = HIWORD (lParam) ;
          
          
          return 0 ;
          
     case WM_PAINT:
		 hCursor = SetCursor (LoadCursor (NULL, IDC_WAIT)) ;
          ShowCursor (TRUE) ;
          
          if (hClipRgn)
               DeleteObject (hClipRgn) ;
          
          hTempRgn[0] = CreateEllipticRgn (0, cyClient / 3,
                                           cxClient / 2, 2 * cyClient / 3) ;
          hTempRgn[1] = CreateEllipticRgn (cxClient / 2, cyClient / 3,
                                           cxClient, 2 * cyClient / 3) ;
          hTempRgn[2] = CreateEllipticRgn (cxClient / 3, 0,
                                           2 * cxClient / 3, cyClient / 2) ;
          hTempRgn[3] = CreateEllipticRgn (cxClient / 3, cyClient / 2,
                                           2 * cxClient / 3, cyClient) ;
          hTempRgn[4] = CreateRectRgn (0, 0, 1, 1) ;
          hTempRgn[5] = CreateRectRgn (0, 0, 1, 1) ;
          hClipRgn    = CreateRectRgn (0, 0, 1, 1) ;
          
          CombineRgn (hTempRgn[4], hTempRgn[0], hTempRgn[1], RGN_OR) ;
          CombineRgn (hTempRgn[5], hTempRgn[2], hTempRgn[3], RGN_OR) ;
          CombineRgn (hClipRgn,    hTempRgn[4], hTempRgn[5], RGN_XOR) ;
          
          for (i = 0 ; i < 6 ; i++)
               DeleteObject (hTempRgn[i]) ;
          
          SetCursor (hCursor) ;
          ShowCursor (FALSE) ;
          hdc = BeginPaint (hwnd, &ps) ;
          
          
          SelectClipRgn (hdc, hClipRgn) ;
	
          SetViewportOrgEx (hdc, cxClient / 2, cyClient / 2, NULL) ;
          fRadius = _hypot (cxClient / 2.0, cyClient / 2.0) ;
          
          DrawLines(hdc, fAngle, fRadius);

          EndPaint (hwnd, &ps) ;
          return 0 ;
          
     case WM_DESTROY:
          DeleteObject (hClipRgn) ;
          PostQuitMessage (0) ;
          return 0 ;
     }
     return DefWindowProc (hwnd, message, wParam, lParam) ;
}