rom/hyperlayers/installlayerhook.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc:
   6     Lang: english
   7 */
   8 #include <aros/libcall.h>
   9 #include <utility/hooks.h>
  10 #include <proto/graphics.h>
  11
  12 #define DEBUG 0
  13 #include <aros/debug.h>
  14 #undef kprintf
  15
  16 /*****************************************************************************
  17
  18     NAME */
  19 #include <proto/layers.h>
  20 #include "layers_intern.h"
  21
  22         AROS_LH2(struct Hook *, InstallLayerHook,
  23
  24 /*  SYNOPSIS */
  25         AROS_LHA(struct Layer *, layer, A0),
  26         AROS_LHA(struct Hook  *, hook, A1),
  27
  28 /*  LOCATION */
  29         struct LayersBase *, LayersBase, 33, Layers)
  30
  31 /*  FUNCTION
  32         Safely install a new backfill hook. Return the old hook.
  33         If hook is NULL, then the default backfill hook will be installed.
  34
  35     INPUTS
  36         layer - layer that will get the new backfill hook
  37         hook  - pointer to backfill hook to be installed
  38
  39     RESULT
  40
  41     NOTES
  42
  43     EXAMPLE
  44
  45     BUGS
  46
  47     SEE ALSO
  48
  49     INTERNALS
  50
  51     HISTORY
  52         27-11-96    digulla automatically created from
  53                             layers_lib.fd and clib/layers_protos.h
  54
  55 *****************************************************************************/
  56 {
  57     AROS_LIBFUNC_INIT
  58     AROS_LIBBASE_EXT_DECL(struct LayersBase *,LayersBase)
  59
  60     struct Hook *OldHook;
  61
  62     D(bug("InstallLayerHook(layer @ $%lx, hook @ $%lx)\n", layer, hook));
  63
  64     if(layer == NULL)
  65         return NULL;
  66
  67     LockLayer(0, layer);
  68
  69     OldHook = layer->BackFill;
  70
  71     layer->BackFill = hook;
  72
  73     UnlockLayer(layer);
  74
  75     return OldHook;
  76
  77     AROS_LIBFUNC_EXIT
  78 } /* InstallLayerHook */