rom/hyperlayers/islayerhiddenbysibling.c

   1 /*
   2     Copyright © 1995-2011, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc:
   6     Lang: english
   7 */
   8
   9 #include <proto/exec.h>
  10 #include <exec/types.h>
  11 #include <aros/libcall.h>
  12 #include <proto/graphics.h>
  13
  14 #include "layers_intern.h"
  15 #include "basicfuncs.h"
  16
  17 /*****************************************************************************
  18
  19     NAME */
  20 #include <proto/layers.h>
  21         AROS_LH2(BOOL, IsLayerHiddenBySibling,
  22
  23 /*  SYNOPSIS */
  24         AROS_LHA(struct Layer *, l              , A0),
  25         AROS_LHA(BOOL          , check_invisible, D0),
  26
  27 /*  LOCATION */
  28         struct LayersBase *, LayersBase, 44, Layers)
  29
  30 /*  FUNCTION
  31        Checks whether this layer is hidden by any siblings
  32        that are in front of it. All these siblings must have
  33        the same priority as that layer.
  34        It can be specified whether invisible siblings are to be
  35        considered in the comparison.
  36
  37     INPUTS
  38        L               - pointer to layer
  39        check_invisible - whether invisible siblings are to be considered
  40
  41     RESULT
  42        TRUE  - layer is hidden by one or more siblings
  43        FALSE - layer is fully visible
  44
  45     NOTES
  46
  47     EXAMPLE
  48
  49     BUGS
  50
  51     SEE ALSO
  52
  53     INTERNALS
  54
  55     HISTORY
  56
  57 *****************************************************************************/
  58 {
  59         AROS_LIBFUNC_INIT
  60
  61         struct Layer * _l;
  62         struct Region * r;
  63         BOOL result = FALSE;
  64
  65         if (NULL == l ||
  66             NULL == (r = NewRegion()))
  67                 return FALSE;
  68
  69         LockLayers(l->LayerInfo);
  70
  71         _l = l->front;
  72
  73         while (NULL != _l) {
  74                 /*
  75                  * If they differ in priority then return FALSE.
  76                  */
  77                 if (_l->priority != l->priority) {
  78                         break;
  79                 }
  80
  81                 /*
  82                  * Only need to check with those layers that
  83                  * have the same nesting count (are immediate
  84                  * siblings to the layer l).
  85                  */
  86                 if (l->nesting == _l->nesting &&
  87                     ( IS_VISIBLE(_l) || TRUE == check_invisible) &&
  88                     TRUE == overlap(_l->visibleshape->bounds, l->visibleshape->bounds))
  89                 {
  90                         /* The layers overlap if an AND operation on
  91                          * both layers' visible region does not
  92                          * leave an empty region.
  93                          */
  94                         SetRegion(l->visibleshape,r);
  95                         AndRegionRegion(_l->visibleshape,r);
  96                         if (NULL != r->RegionRectangle) {
  97                                 result = TRUE;
  98                                 break;
  99                         }
 100                 }
 101                 _l = _l->front;
 102         }
 103
 104         UnlockLayers(l->LayerInfo);
 105
 106         DisposeRegion(r);
 107
 108         return result;
 109
 110         AROS_LIBFUNC_EXIT
 111 } /* IsLayerHiddenBySibling */