rom/hyperlayers/islayerhiddenbysibling.c

   1 /*
   2     Copyright © 1995-2007, 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 "layers_intern.h"
  11 #include <aros/libcall.h>
  12 #include <proto/graphics.h>
  13 #include "basicfuncs.h"
  14 #include "../graphics/intregions.h"
  15
  16 /*****************************************************************************
  17
  18     NAME */
  19 #include <proto/layers.h>
  20         AROS_LH2(BOOL, IsLayerHiddenBySibling,
  21
  22 /*  SYNOPSIS */
  23         AROS_LHA(struct Layer *, l              , A0),
  24         AROS_LHA(BOOL          , check_invisible, D0),
  25
  26 /*  LOCATION */
  27         struct LayersBase *, LayersBase, 44, Layers)
  28
  29 /*  FUNCTION
  30        Checks whether this layer is hidden by any siblings
  31        that are in front of it. All these siblings must have
  32        the same priority as that layer.
  33        It can be specified whether invisible siblings are to be
  34        considered in the comparison.
  35
  36     INPUTS
  37        L               - pointer to layer
  38        check_invisible - whether invisible siblings are to be considered
  39
  40     RESULT
  41        TRUE  - layer is hidden by one or more siblings
  42        FALSE - layer is fully visible
  43
  44     NOTES
  45
  46     EXAMPLE
  47
  48     BUGS
  49
  50     SEE ALSO
  51
  52     INTERNALS
  53
  54     HISTORY
  55
  56 *****************************************************************************/
  57 {
  58         AROS_LIBFUNC_INIT
  59
  60         struct Layer * _l;
  61         struct Region * r;
  62         BOOL result = FALSE;
  63
  64         if (NULL == l ||
  65             NULL == (r = NewRegion()))
  66                 return FALSE;
  67
  68         LockLayers(l->LayerInfo);
  69
  70         _l = l->front;
  71
  72         while (NULL != _l) {
  73                 /*
  74                  * If they differ in priority then return FALSE.
  75                  */
  76                 if (_l->priority != l->priority) {
  77                         break;
  78                 }
  79
  80                 /*
  81                  * Only need to check with those layers that
  82                  * have the same nesting count (are immediate
  83                  * siblings to the layer l).
  84                  */
  85                 if (l->nesting == _l->nesting &&
  86                     ( IS_VISIBLE(_l) || TRUE == check_invisible) &&
  87                     TRUE == overlap(_l->visibleshape->bounds, l->visibleshape->bounds))
  88                 {
  89                         /* The layers overlap if an AND operation on
  90                          * both layers' visible region does not
  91                          * leave an empty region.
  92                          */
  93                         SetRegion(l->visibleshape,r);
  94                         AndRegionRegion(_l->visibleshape,r);
  95                         if (NULL != r->RegionRectangle) {
  96                                 result = TRUE;
  97                                 break;
  98                         }
  99                 }
 100                 _l = _l->front;
 101         }
 102
 103         UnlockLayers(l->LayerInfo);
 104
 105         DisposeRegion(r);
 106
 107         return result;
 108
 109         AROS_LIBFUNC_EXIT
 110 } /* IsLayerHiddenBySibling */