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Microsoft OS/2 SDK PM 02-24-1989

/*--------------------------------
   SPIRAL.C -- GPI Spiral Drawing
 ---------------------------------*/

#include <os2.h>
#include <math.h>

#define NUMPOINTS 1000
#define NUMREV    20
#define PI        3.14159

MRESULT EXPENTRY ClientWndProc (HWND, USHORT, MPARAM, MPARAM) ;

int main (void)
     {
     static CHAR  szClientClass [] = "Spiral" ;
     static ULONG flFrameFlags = FCF_TITLEBAR      | FCF_SYSMENU |
                                 FCF_SIZEBORDER    | FCF_MINMAX  |
                                 FCF_SHELLPOSITION | FCF_TASKLIST ;
     HAB          hab ;
     HMQ          hmq ;
     HWND         hwndFrame, hwndClient ;
     QMSG         qmsg ;

     hab = WinInitialize (0) ;
     hmq = WinCreateMsgQueue (hab, 0) ;

     WinRegisterClass (hab, szClientClass, ClientWndProc, CS_SIZEREDRAW, 0) ;

     hwndFrame = WinCreateStdWindow (HWND_DESKTOP, WS_VISIBLE,
                                     &flFrameFlags, szClientClass, NULL,
                                     0L, NULL, 0, &hwndClient) ;

     while (WinGetMsg (hab, &qmsg, NULL, 0, 0))
          WinDispatchMsg (hab, &qmsg) ;

     WinDestroyWindow (hwndFrame) ;
     WinDestroyMsgQueue (hmq) ;
     WinTerminate (hab) ;
     return 0 ;
     }

MRESULT EXPENTRY ClientWndProc (HWND hwnd, USHORT msg, MPARAM mp1, MPARAM mp2)
     {
     static SHORT cxClient, cyClient ;
     double       dAngle, dScale ;
     HPS          hps ;
     PPOINTL      pptl ;
     SEL          sel ;
     SHORT        sIndex ;

     switch (msg)
	  {
          case WM_SIZE:
               cxClient = SHORT1FROMMP (mp2) ;
               cyClient = SHORT2FROMMP (mp2) ;
               return 0 ;

          case WM_PAINT:
               hps = WinBeginPaint (hwnd, NULL, NULL) ;
               GpiErase (hps) ;

               if (!DosAllocSeg (NUMPOINTS * sizeof (POINTL), &sel, 0))
                    {
                    pptl = MAKEP (sel, 0) ;

                    for (sIndex = 0 ; sIndex < NUMPOINTS ; sIndex ++)
                        {
                        dAngle = sIndex * 2 * PI / (NUMPOINTS / NUMREV) ;
                        dScale = 1 - (double) sIndex / NUMPOINTS ;

                        pptl[sIndex].x = (LONG) (cxClient / 2 *
                                                 (1 + dScale * cos (dAngle))) ;

                        pptl[sIndex].y = (LONG) (cyClient / 2 *
                                                 (1 + dScale * sin (dAngle))) ;
                        }
                    GpiMove (hps, pptl) ;
                    GpiPolyLine (hps, NUMPOINTS - 1L, pptl + 1) ;

                    DosFreeSeg (sel) ;
                    }
               WinEndPaint (hps) ;
               return 0 ;
          }
     return WinDefWindowProc (hwnd, msg, mp1, mp2) ;
     }

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