rom/utility/gettagdata.c

   1 /*
   2     Copyright © 1995-2004, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     GetTagData()
   6 */
   7 #include "intern.h"
   8
   9 /*****************************************************************************
  10
  11     NAME */
  12 #include <utility/tagitem.h>
  13 #include <proto/utility.h>
  14
  15         AROS_LH3(IPTR, GetTagData,
  16
  17 /*  SYNOPSIS */
  18         AROS_LHA(Tag                   , tagValue, D0),
  19         AROS_LHA(IPTR                  , defaultVal, D1),
  20         AROS_LHA(const struct TagItem *, tagList, A0),
  21
  22 /*  LOCATION */
  23         struct UtilityBase *, UtilityBase, 6, Utility)
  24
  25 /*  FUNCTION
  26         Searches the TagList for the Tag specified, if it exists, then
  27         returns the ti_Data field of that Tag, otherwise returns the
  28         supplied default value.
  29
  30     INPUTS
  31         tagValue    -   Tag to search for.
  32         defaultVal  -   Default value for the Tag.
  33         tagList     -   Pointer to first TagItem in the list.
  34
  35     RESULT
  36         The data value if the Tag exists, or the default value if it
  37         doesn't.
  38
  39     NOTES
  40         If the input TagList doesn't exist (eg for some reason equals
  41         NULL), then the return value will be NULL. This way you can
  42         check for broken code, whereas returing the default would allow
  43         code that is possibly buggy to still seem to work. (Until you
  44         tried to do anything special at least).
  45
  46     EXAMPLE
  47
  48         struct Window *window;      \* The Window we are creating *\
  49         struct TagItem *wintags;    \* Tags for this window *\
  50
  51         \* Find out the value for the WA_Left tag *\
  52         window->Left = GetTagData( WA_Left, 320, wintags )
  53
  54     BUGS
  55
  56     SEE ALSO
  57         utility/tagitem.h
  58
  59     INTERNALS
  60
  61 *****************************************************************************/
  62 {
  63     AROS_LIBFUNC_INIT
  64     struct TagItem *ti = NULL;
  65
  66     /*
  67         If we can find the Tag in the supplied list, then return the
  68         ti_Data fields value.
  69
  70         If the tag is not in the list, just return the default value.
  71     */
  72     if (tagList && (ti = FindTagItem(tagValue, tagList)))
  73         return ti->ti_Data;
  74
  75     return defaultVal;
  76     AROS_LIBFUNC_EXIT
  77 } /* GetTagData */