rom/graphics/obtainbestpena.c

   1 /*
   2     Copyright © 1995-2018, 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
   9 #include "graphics_intern.h"
  10 #include <proto/utility.h>
  11 #include <utility/tagitem.h>
  12 #include <graphics/view.h>
  13
  14 /*****************************************************************************
  15
  16     NAME */
  17         #include <proto/graphics.h>
  18
  19         AROS_LH5(LONG, ObtainBestPenA,
  20
  21 /*  SYNOPSIS */
  22         AROS_LHA(struct ColorMap *, cm  , A0),
  23         AROS_LHA(ULONG            , r   , D1),
  24         AROS_LHA(ULONG            , g   , D2),
  25         AROS_LHA(ULONG            , b   , D3),
  26         AROS_LHA(struct TagItem * , tags, A1),
  27
  28 /*  LOCATION */
  29         struct GfxBase *, GfxBase, 140, Graphics)
  30
  31 /*  FUNCTION
  32         Try to find a pen which matches the given parameters.
  33
  34     INPUTS
  35         cm   - colormap
  36         r    - red value (32 bit left justified fraction)
  37         g    - green value (32 bit left justified fraction)
  38         b    - blue value (32 bit left justified fraction)
  39         tags - tagarray
  40                OBP_Precision - PRECISION_GUI, PRECISION_ICON, PRECISION_IMAGE or PRECISION_EXACT.
  41                                Defaults to PRECISION_IMAGE.
  42
  43                OBP_FailIfBad - if TRUE ObtainBestPen returns an error when there
  44                                is no color in the given tolerance.
  45
  46     RESULT
  47         A pen value or -1 if no pen could be found.
  48
  49     NOTES
  50         You must call ReleasePen() when you're done with the pen.
  51
  52     EXAMPLE
  53
  54     BUGS
  55
  56     SEE ALSO
  57
  58     INTERNALS
  59
  60     HISTORY
  61
  62 *****************************************************************************/
  63 {
  64     AROS_LIBFUNC_INIT
  65
  66     struct PaletteExtra         *pe = cm->PalExtra;
  67     LONG                        retval = -1;
  68     PalExtra_AllocList_Type     index;
  69
  70     if (NULL != pe)
  71     {
  72         struct TagItem  defaults[] =
  73         {
  74             {OBP_Precision, PRECISION_IMAGE },
  75             {OBP_FailIfBad, FALSE           }
  76         };
  77         ULONG           best_distance = (ULONG)-1;
  78
  79
  80         /*
  81         ** override the defaults if necessary
  82         */
  83         defaults[0].ti_Data = GetTagData(OBP_Precision,
  84                                          defaults[0].ti_Data,
  85                                          tags);
  86
  87         defaults[1].ti_Data = GetTagData(OBP_FailIfBad,
  88                                          defaults[1].ti_Data,
  89                                          tags);
  90
  91         /*
  92         ** let nobody else play with the PalExtra structure
  93         */
  94         ObtainSemaphore(&pe->pe_Semaphore);
  95
  96         /*
  97         ** Walk through the list of shared pens and search
  98         ** for the closest color.
  99         */
 100         index = (PalExtra_AllocList_Type)pe->pe_FirstShared;
 101         while ((PalExtra_AllocList_Type)-1 != index)
 102         {
 103             ULONG distance = color_distance(cm,r,g,b,index);
 104
 105             if (distance < best_distance)
 106             {
 107                 best_distance = distance;
 108                 retval        = index;
 109             }
 110
 111             index = PALEXTRA_ALLOCLIST(pe, index);
 112         }
 113
 114         /* FIXME: The color distance calc might be different than in AmigaOS. */
 115
 116         /*
 117         ** If the best distance to an available color is greater than
 118         ** the square of the tolerance, try to allocate a better
 119         ** color, otherwise increase the shared counter for that color.
 120         ** If only a little amount of colors is free for allocation in the
 121         ** colormap the restrictions towards color matching should be
 122         ** much looser than if the amount of allocated colors is close to 0.
 123         ** The autodocs say that.
 124         */
 125         if (
 126             (retval == -1) ||
 127             (PRECISION_EXACT == defaults[0].ti_Data && 0 != best_distance ) ||
 128             (best_distance * pe->pe_NFree  >
 129             (defaults[0].ti_Data * defaults[0].ti_Data) * pe->pe_SharableColors
 130             )
 131            )
 132         {
 133             /*
 134             ** The given tolerance could not be accomplished.
 135             ** Try to allocate a pen. If that fails we
 136             ** return -1 if the user specified OBP_FailIfBad = TRUE.
 137             */
 138             LONG tmp = ObtainPen(cm,-1,r,g,b,0);
 139
 140             if (-1 == tmp)
 141             {
 142                 /*
 143                 ** Return -1 if the user is strict with color matching.
 144                 ** In the other case retval is not changed.
 145                 */
 146                 if (defaults[1].ti_Data)
 147                 {
 148                     retval = -1;
 149                 }
 150                 else if (retval != -1)
 151                 {
 152                     /*
 153                     ** One more application is using this color
 154                     */
 155
 156                     PALEXTRA_REFCNT(pe, retval)++;
 157                 }
 158             }
 159             else
 160                 retval = tmp;
 161         }
 162         else
 163         {
 164             /*
 165             ** One more application is using this color
 166             */
 167             PALEXTRA_REFCNT(pe, retval)++;
 168         }
 169
 170         ReleaseSemaphore(&pe->pe_Semaphore);
 171
 172     } /* if (NULL != pe) */
 173
 174     return retval;
 175
 176     AROS_LIBFUNC_EXIT
 177
 178 } /* ObtainBestPenA */