rom/graphics/obtainbestpena.c

   1 /*
   2     Copyright © 1995-2007, 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         Try to find a pen which matches the given parameters.
  32
  33     INPUTS
  34         cm   - colormap
  35         r    - red value (32 bit left justified fraction)
  36         g    - green value (32 bit left justified fraction)
  37         b    - blue value (32 bit left justified fraction)
  38         tags - tagarray
  39                OBP_Precision - PRECISION_GUI, PRECISION_ICON, PRECISION_IMAGE or PRECISION_EXACT.
  40                                Defaults to PRECISION_IMAGE.
  41
  42                OBP_FailIfBad - if TRUE ObtainBestPen returns an error when there
  43                                is no color in the given tolerance.
  44
  45     RESULT
  46         A pen value or -1 if no pen could be found.
  47
  48     NOTES
  49         You must call ReleasePen() when you're done with the pen.
  50
  51     EXAMPLE
  52
  53     BUGS
  54
  55     SEE ALSO
  56
  57     INTERNALS
  58
  59     HISTORY
  60
  61 *****************************************************************************/
  62 {
  63     AROS_LIBFUNC_INIT
  64
  65     struct PaletteExtra         *pe = cm->PalExtra;
  66     LONG                        retval = -1;
  67     PalExtra_AllocList_Type     index;
  68
  69     if (NULL != pe)
  70     {
  71         struct TagItem  defaults[] =
  72         {
  73             {OBP_Precision, PRECISION_IMAGE },
  74             {OBP_FailIfBad, FALSE           }
  75         };
  76         ULONG           best_distance = (ULONG)-1;
  77
  78
  79         /*
  80         ** override the defaults if necessary
  81         */
  82         defaults[0].ti_Data = GetTagData(OBP_Precision,
  83                                          defaults[0].ti_Data,
  84                                          tags);
  85
  86         defaults[1].ti_Data = GetTagData(OBP_FailIfBad,
  87                                          defaults[1].ti_Data,
  88                                          tags);
  89
  90         /*
  91         ** let nobody else play with the PalExtra structure
  92         */
  93         ObtainSemaphore(&pe->pe_Semaphore);
  94
  95         /*
  96         ** Walk through the list of shared pens and search
  97         ** for the closest color.
  98         */
  99         index = (PalExtra_AllocList_Type)pe->pe_FirstShared;
 100         while ((PalExtra_AllocList_Type)-1 != index)
 101         {
 102             ULONG distance = color_distance(cm,r,g,b,index);
 103
 104             if (distance < best_distance)
 105             {
 106                 best_distance = distance;
 107                 retval        = index;
 108             }
 109
 110             index = PALEXTRA_ALLOCLIST(pe, index);
 111         }
 112
 113         /* FIXME: The color distance calc might be different than in AmigaOS. */
 114
 115         /*
 116         ** If the best distance to an available color is greater than
 117         ** the square of the tolerance, try to allocate a better
 118         ** color, otherwise increase the shared counter for that color.
 119         ** If only a little amount of colors is free for allocation in the
 120         ** colormap the restrictions towards color matching should be
 121         ** much looser than if the amount of free colors is close to 0.
 122         ** The autodocs say that.
 123         */
 124         if (
 125             (retval == -1) ||
 126             (PRECISION_EXACT == defaults[0].ti_Data && 0 != best_distance ) ||
 127             (best_distance * pe->pe_NFree  >
 128             (defaults[0].ti_Data * defaults[0].ti_Data) * pe->pe_SharableColors
 129             )
 130            )
 131         {
 132             /*
 133             ** The given tolerance could not be accomplished.
 134             ** Try to allocate a pen. If that fails we
 135             ** return -1 if the user specified OBP_FailIfBad = TRUE.
 136             */
 137             LONG tmp = ObtainPen(cm,-1,r,g,b,0);
 138
 139             if (-1 == tmp)
 140             {
 141                 /*
 142                 ** Return -1 if the user is strict with color matching.
 143                 ** In the other case retval is not changed.
 144                 */
 145                 if (defaults[1].ti_Data)
 146                 {
 147                     retval = -1;
 148                 }
 149                 else if (retval != -1)
 150                 {
 151                     /*
 152                     ** One more application is using this color
 153                     */
 154
 155                     PALEXTRA_REFCNT(pe, retval)++;
 156                 }
 157             }
 158             else
 159                 retval = tmp;
 160         }
 161         else
 162         {
 163             /*
 164             ** One more application is using this color
 165             */
 166             PALEXTRA_REFCNT(pe, retval)++;
 167         }
 168
 169         ReleaseSemaphore(&pe->pe_Semaphore);
 170
 171     } /* if (NULL != pe) */
 172
 173     return retval;
 174
 175     AROS_LIBFUNC_EXIT
 176
 177 } /* ObtainBestPenA */