rom/graphics/obtainbestpena.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Obtain the best pen available for a given color
   6     Lang: english
   7 */
   8 #include "graphics_intern.h"
   9 #include <proto/utility.h>
  10 #include <utility/tagitem.h>
  11 #include <graphics/view.h>
  12
  13 /*****************************************************************************
  14
  15     NAME */
  16         #include <proto/graphics.h>
  17
  18         AROS_LH5(LONG, ObtainBestPenA,
  19
  20 /*  SYNOPSIS */
  21         AROS_LHA(struct ColorMap *, cm  , A0),
  22         AROS_LHA(ULONG            , r   , D1),
  23         AROS_LHA(ULONG            , g   , D2),
  24         AROS_LHA(ULONG            , b   , D3),
  25         AROS_LHA(struct TagItem * , tags, A1),
  26
  27 /*  LOCATION */
  28         struct GfxBase *, GfxBase, 140, Graphics)
  29
  30 /*  FUNCTION
  31
  32     INPUTS
  33
  34     RESULT
  35
  36     NOTES
  37
  38     EXAMPLE
  39
  40     BUGS
  41
  42     SEE ALSO
  43
  44     INTERNALS
  45
  46     HISTORY
  47
  48 *****************************************************************************/
  49 {
  50     AROS_LIBFUNC_INIT
  51     AROS_LIBBASE_EXT_DECL(struct GfxBase *,GfxBase)
  52
  53     struct PaletteExtra         *pe = cm->PalExtra;
  54     LONG                        retval = -1;
  55     PalExtra_AllocList_Type     index;
  56
  57     if (NULL != pe)
  58     {
  59         struct TagItem  defaults[] =
  60         {
  61             {OBP_Precision, PRECISION_IMAGE },
  62             {OBP_FailIfBad, FALSE           }
  63         };
  64         ULONG           best_distance = (ULONG)-1;
  65
  66
  67         /*
  68         ** override the defaults if necessary
  69         */
  70         defaults[0].ti_Data = GetTagData(OBP_Precision,
  71                                          defaults[0].ti_Data,
  72                                          tags);
  73
  74         defaults[1].ti_Data = GetTagData(OBP_FailIfBad,
  75                                          defaults[1].ti_Data,
  76                                          tags);
  77
  78         /*
  79         ** let nobody else play with the PalExtra structure
  80         */
  81         ObtainSemaphore(&pe->pe_Semaphore);
  82
  83         /*
  84         ** Walk through the list of shared pens and search
  85         ** for the closest color.
  86         */
  87         index = (PalExtra_AllocList_Type)pe->pe_FirstShared;
  88         while ((PalExtra_AllocList_Type)-1 != index)
  89         {
  90             ULONG distance = color_distance(cm,r,g,b,index);
  91
  92             if (distance < best_distance)
  93             {
  94                 best_distance = distance;
  95                 retval        = index;
  96             }
  97
  98             index = PALEXTRA_ALLOCLIST(pe, index);
  99         }
 100
 101         #warning The color distance calc might be different than in AmigaOS.
 102
 103         /*
 104         ** If the best distance to an available color is greater than
 105         ** the square of the tolerance, try to allocate a better
 106         ** color, otherwise increase the shared counter for that color.
 107         ** If only a little amount of colors is free for allocation in the
 108         ** colormap the restrictions towards color matching should be
 109         ** much looser than if the amount of free colors is close to 0.
 110         ** The autodocs say that.
 111         */
 112         if (
 113             (retval == -1) ||
 114             (PRECISION_EXACT == defaults[0].ti_Data && 0 != best_distance ) ||
 115             (best_distance * pe->pe_NFree  >
 116             (defaults[0].ti_Data * defaults[0].ti_Data) * pe->pe_SharableColors
 117             )
 118            )
 119         {
 120             /*
 121             ** The given tolerance could not be accomplished.
 122             ** Try to allocate a pen. If that fails we
 123             ** return -1 if the user specified OBP_FailIfBad = TRUE.
 124             */
 125             LONG tmp = ObtainPen(cm,-1,r,g,b,0);
 126
 127             if (-1 == tmp)
 128             {
 129                 /*
 130                 ** Return -1 if the user is strict with color matching.
 131                 ** In the other case retval is not changed.
 132                 */
 133                 if (TRUE == defaults[1].ti_Data)
 134                 {
 135                     retval = -1;
 136                 }
 137                 else if (retval != -1)
 138                 {
 139                     /*
 140                     ** One more application is using this color
 141                     */
 142
 143                     PALEXTRA_REFCNT(pe, retval)++;
 144                 }
 145             }
 146             else
 147                 retval = tmp;
 148         }
 149         else
 150         {
 151             /*
 152             ** One more application is using this color
 153             */
 154             PALEXTRA_REFCNT(pe, retval)++;
 155         }
 156
 157         ReleaseSemaphore(&pe->pe_Semaphore);
 158
 159     } /* if (NULL != pe) */
 160
 161     return retval;
 162
 163     AROS_LIBFUNC_EXIT
 164
 165 } /* ObtainBestPenA */