rom/hyperlayers/isfrontmostlayer.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc:
   6     Lang: english
   7 */
   8 #include <proto/exec.h>
   9 #include <exec/types.h>
  10 #include <exec/memory.h>
  11 #include <layers_intern.h>
  12 #include <aros/libcall.h>
  13 #include <proto/graphics.h>
  14 #include "basicfuncs.h"
  15
  16 /*****************************************************************************
  17
  18     NAME */
  19 #include <proto/layers.h>
  20         AROS_LH2(BOOL, IsFrontmostLayer,
  21
  22 /*  SYNOPSIS */
  23         AROS_LHA(struct Layer *, l              , A0),
  24         AROS_LHA(BOOL          , check_invisible, D0),
  25
  26 /*  LOCATION */
  27         struct LayersBase *, LayersBase, 43, Layers)
  28
  29 /*  FUNCTION
  30        Checks whether this layer is the frontmost layer within
  31        its priority. If this layer has children then all of
  32        its children will be disregarded. Comparisons are only
  33        done with layers that have the same 'depth' of relation-
  34        ship (=nesting counter) to the root layer.
  35        It can be specified whether invisible siblings are to be
  36        considered in the comparison.
  37
  38     INPUTS
  39        L               - pointer to layer
  40        check_invisible - whether invisible siblings are to be considered
  41
  42
  43     RESULT
  44        TRUE  - layer is frontmost layer within its priority
  45        FALSE - layer is not frontmost layer within its priority
  46
  47     NOTES
  48
  49     EXAMPLE
  50
  51     BUGS
  52
  53     SEE ALSO
  54
  55     INTERNALS
  56
  57     HISTORY
  58
  59 *****************************************************************************/
  60 {
  61         AROS_LIBFUNC_INIT
  62         AROS_LIBBASE_EXT_DECL(struct LayersBase *,LayersBase)
  63
  64         struct Layer * _l;
  65         BOOL result = TRUE;
  66
  67         if (NULL == l)
  68                 return FALSE;
  69
  70         LockLayers(l->LayerInfo);
  71
  72         _l = l->front;
  73
  74         while (NULL != _l) {
  75                 /*
  76                  * If they differ in priority then return TRUE.
  77                  * I did not meet another (elegible) sibling so
  78                  * far.
  79                  */
  80                 if (_l->priority != l->priority)
  81                         break;
  82                 /*
  83                  * If the nesting counter of one layer in front
  84                  * of the layer l is equal (or less) then return FALSE.
  85                  */
  86                 if (_l->nesting  <= l->nesting &&
  87                     ( IS_VISIBLE(_l) || TRUE == check_invisible)) {
  88                         result = FALSE;
  89                         break;
  90                 }
  91                 _l = _l->front;
  92         }
  93
  94         UnlockLayers(l->LayerInfo);
  95
  96         return result;
  97
  98         AROS_LIBFUNC_EXIT
  99 } /* IsFrontmostLayer */