rom/graphics/areaellipse.c

   1 /*
   2     Copyright © 1995-2007, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Graphics function AreaEllipse()
   6     Lang: english
   7 */
   8 #include <exec/types.h>
   9 #include <graphics/rastport.h>
  10 #include "graphics_intern.h"
  11 #include "gfxfuncsupport.h"
  12
  13 /*****************************************************************************
  14
  15     NAME */
  16 #include <proto/graphics.h>
  17
  18         AROS_LH5(ULONG, AreaEllipse,
  19
  20 /*  SYNOPSIS */
  21         AROS_LHA(struct RastPort *, rp, A1),
  22         AROS_LHA(WORD             , cx, D0),
  23         AROS_LHA(WORD             , cy, D1),
  24         AROS_LHA(WORD             , a , D2),
  25         AROS_LHA(WORD             , b , D3),
  26
  27 /*  LOCATION */
  28         struct GfxBase *, GfxBase, 31, Graphics)
  29
  30 /*  FUNCTION
  31         Add an ellipse to the vector buffer. An ellipse takes up two
  32         entries in the buffer.
  33
  34     INPUTS
  35         rp - pointer to a valid RastPort structure with a pointer to
  36              the previously initialized AreaInfo structure.
  37         cx - x coordinate of the center point relative to rastport
  38         cy - y coordinate of the center point relative to rastport
  39         a  - horizontal radius of the ellipse (> 0)
  40         b  - vertical radius of the ellipse (> 0)
  41
  42     RESULT
  43         error -  0 for success
  44                 -1 if the vector collection matrix is full
  45
  46     NOTES
  47
  48     EXAMPLE
  49
  50     BUGS
  51
  52     SEE ALSO
  53         InitArea(), AreaMove(), AreaDraw(), AreaCircle()
  54         graphics/rastport.h
  55
  56     INTERNALS
  57
  58     HISTORY
  59
  60 *****************************************************************************/
  61 {
  62     AROS_LIBFUNC_INIT
  63
  64     struct AreaInfo * areainfo = rp->AreaInfo;
  65
  66     /*  Is there still enough storage area in the areainfo-buffer?
  67      *  We need at least a storage area for two vectors
  68      */
  69     if (areainfo->Count + 2 <= areainfo->MaxCount)
  70     {
  71         FIX_GFXCOORD(cx);
  72         FIX_GFXCOORD(cy);
  73         FIX_GFXCOORD(a);
  74         FIX_GFXCOORD(b);
  75
  76         /* is this the very first entry in the vector collection matrix */
  77         if (0 == areainfo->Count)
  78         {
  79             areainfo->VctrPtr[0] = cx;
  80             areainfo->VctrPtr[1] = cy;
  81             areainfo->FlagPtr[0] = AREAINFOFLAG_ELLIPSE;
  82
  83             areainfo->VctrPtr[2] = a;
  84             areainfo->VctrPtr[3] = b;
  85             areainfo->FlagPtr[1] = AREAINFOFLAG_ELLIPSE;
  86
  87             areainfo->VctrPtr    = &areainfo->VctrPtr[4];
  88             areainfo->FlagPtr    = &areainfo->FlagPtr[2];
  89
  90             areainfo->Count += 2;
  91         }
  92         else
  93         {
  94             areaclosepolygon(areainfo);
  95
  96             /* Need to check again, if there is enough room, because
  97                areaclosepolygon might have eaten one vector!! */
  98
  99             if (areainfo->Count + 2 > areainfo->MaxCount)
 100                 return -1;
 101
 102             /*  If the previous command in the vector collection matrix was a move then
 103              *  erase that one
 104              */
 105
 106             if (AREAINFOFLAG_MOVE == areainfo->FlagPtr[-1])
 107             {
 108                 areainfo->VctrPtr = &areainfo->VctrPtr[-2];
 109                 areainfo->FlagPtr--;
 110                 areainfo->Count--;
 111             }
 112
 113             /* still enough storage area?? */
 114             if (areainfo->Count + 2 <= areainfo->MaxCount)
 115             {
 116                 areainfo->VctrPtr[0] = cx;
 117                 areainfo->VctrPtr[1] = cy;
 118                 areainfo->FlagPtr[0] = AREAINFOFLAG_ELLIPSE;
 119
 120                 areainfo->VctrPtr[2] = a;
 121                 areainfo->VctrPtr[3] = b;
 122                 areainfo->FlagPtr[1] = AREAINFOFLAG_ELLIPSE;
 123
 124                 areainfo->VctrPtr    = &areainfo->VctrPtr[4];
 125                 areainfo->FlagPtr    = &areainfo->FlagPtr[2];
 126
 127                 areainfo->Count += 2;
 128
 129                 return 0;
 130             }
 131             else
 132                 return -1;
 133
 134         } /* else branch of if (0 == areainfo->Count) */
 135
 136         /* will never get to this point! */
 137
 138     } /* if (areainfo->Count + 2 < areainfo->MaxCount) */
 139
 140     return -1;
 141
 142     AROS_LIBFUNC_EXIT
 143
 144 } /* AreaEllipse */