BOOL FASTCALL PATH_Arc	(	PDC	dc,
		INT	x1,
		INT	y1,
		INT	x2,
		INT	y2,
		INT	xStart,
		INT	yStart,
		INT	xEnd,
		INT	yEnd,
		INT	lines
	)
Definition at line 496 of file path.c.
Referenced by IntGdiArcInternal(), and PATH_Ellipse().
{
  double  angleStart, angleEnd, angleStartQuadrant, angleEndQuadrant=0.0;
          /* Initialize angleEndQuadrant to silence gcc's warning */
  double  x, y;
  FLOAT_POINT corners[2], pointStart, pointEnd;
  POINT   centre, pointCurPos;
  BOOL    start, end, Ret = TRUE;
  INT     temp;
  BOOL    clockwise;
  PPATH   pPath;

  /* FIXME: This function should check for all possible error returns */
  /* FIXME: Do we have to respect newStroke? */

  ASSERT ( dc );

  pPath = PATH_LockPath( dc->dclevel.hPath );
  if (!pPath) return FALSE;

  clockwise = ((dc->dclevel.flPath & DCPATH_CLOCKWISE) != 0);

  /* Check that path is open */
  if ( pPath->state != PATH_Open )
  {
    Ret = FALSE;
    goto ArcExit;
  }

  /* Check for zero height / width */
  /* FIXME: Only in GM_COMPATIBLE? */
  if ( x1==x2 || y1==y2 )
  {
    Ret = TRUE;
    goto ArcExit;
  }
  /* Convert points to device coordinates */
  corners[0].x=(FLOAT)x1;
  corners[0].y=(FLOAT)y1;
  corners[1].x=(FLOAT)x2;
  corners[1].y=(FLOAT)y2;
  pointStart.x=(FLOAT)xStart;
  pointStart.y=(FLOAT)yStart;
  pointEnd.x=(FLOAT)xEnd;
  pointEnd.y=(FLOAT)yEnd;
  INTERNAL_LPTODP_FLOAT(dc, corners);
  INTERNAL_LPTODP_FLOAT(dc, corners+1);
  INTERNAL_LPTODP_FLOAT(dc, &pointStart);
  INTERNAL_LPTODP_FLOAT(dc, &pointEnd);

  /* Make sure first corner is top left and second corner is bottom right */
  if ( corners[0].x > corners[1].x )
  {
    temp=corners[0].x;
    corners[0].x=corners[1].x;
    corners[1].x=temp;
  }
  if ( corners[0].y > corners[1].y )
  {
    temp=corners[0].y;
    corners[0].y=corners[1].y;
    corners[1].y=temp;
  }

  /* Compute start and end angle */
  PATH_NormalizePoint(corners, &pointStart, &x, &y);
  angleStart=atan2(y, x);
  PATH_NormalizePoint(corners, &pointEnd, &x, &y);
  angleEnd=atan2(y, x);

  /* Make sure the end angle is "on the right side" of the start angle */
  if ( clockwise )
  {
    if ( angleEnd <= angleStart )
    {
      angleEnd+=2*M_PI;
      ASSERT(angleEnd>=angleStart);
    }
  }
  else
  {
    if(angleEnd>=angleStart)
    {
      angleEnd-=2*M_PI;
      ASSERT(angleEnd<=angleStart);
    }
  }

  /* In GM_COMPATIBLE, don't include bottom and right edges */
  if (dc->pdcattr->iGraphicsMode == GM_COMPATIBLE )
  {
    corners[1].x--;
    corners[1].y--;
  }

  /* arcto: Add a PT_MOVETO only if this is the first entry in a stroke */
  if(lines==GdiTypeArcTo && pPath->newStroke) // -1
  {
     pPath->newStroke=FALSE;
     IntGetCurrentPositionEx ( dc, &pointCurPos );
     CoordLPtoDP(dc, &pointCurPos);
     if(!PATH_AddEntry(pPath, &pointCurPos, PT_MOVETO))
     {
       Ret = FALSE;
       goto ArcExit;
     }
  }

  /* Add the arc to the path with one Bezier spline per quadrant that the
   * arc spans */
  start=TRUE;
  end=FALSE;
  do
  {
    /* Determine the start and end angles for this quadrant */
    if(start)
    {
      angleStartQuadrant=angleStart;
      if ( clockwise )
        angleEndQuadrant=(floor(angleStart/M_PI_2)+1.0)*M_PI_2;
      else
        angleEndQuadrant=(ceil(angleStart/M_PI_2)-1.0)*M_PI_2;
    }
    else
    {
      angleStartQuadrant=angleEndQuadrant;
      if ( clockwise )
        angleEndQuadrant+=M_PI_2;
      else
        angleEndQuadrant-=M_PI_2;
    }

    /* Have we reached the last part of the arc? */
    if ( (clockwise && angleEnd<angleEndQuadrant)
      || (!clockwise && angleEnd>angleEndQuadrant)
      )
    {
      /* Adjust the end angle for this quadrant */
     angleEndQuadrant = angleEnd;
     end = TRUE;
    }

    /* Add the Bezier spline to the path */
    PATH_DoArcPart ( pPath, corners, angleStartQuadrant, angleEndQuadrant,
       start ? (lines==GdiTypeArcTo ? PT_LINETO : PT_MOVETO) : FALSE ); // -1
    start = FALSE;
  } while(!end);

  /* chord: close figure. pie: add line and close figure */
  if (lines==GdiTypeChord) // 1
  {
      IntGdiCloseFigure(pPath);
  }
  else if (lines==GdiTypePie) // 2
  {
      centre.x = (corners[0].x+corners[1].x)/2;
      centre.y = (corners[0].y+corners[1].y)/2;
      if(!PATH_AddEntry(pPath, &centre, PT_LINETO | PT_CLOSEFIGURE))
         Ret = FALSE;
  }
ArcExit:
  PATH_UnlockPath( pPath );
  return Ret;
}
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