lib/objchange.c

   1 /* Dia -- an diagram creation/manipulation program
   2  * Copyright (C) 1999 Alexander Larsson
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  */
  18
  19 #include <config.h>
  20
  21 #include "object.h"
  22
  23 /******** ObjectChange for object that just need to get/set state: *****/
  24
  25 typedef struct _ObjectStateChange ObjectStateChange;
  26
  27 struct _ObjectStateChange {
  28   ObjectChange obj_change;
  29
  30   GetStateFunc get_state;
  31   SetStateFunc set_state;
  32
  33   ObjectState *saved_state;
  34   DiaObject *obj;
  35 };
  36
  37 static void
  38 object_state_change_apply_revert(ObjectStateChange *change, DiaObject *obj)
  39 {
  40   ObjectState *old_state;
  41
  42   old_state = change->get_state(change->obj);
  43
  44   change->set_state(change->obj, change->saved_state);
  45
  46   change->saved_state = old_state;
  47 }
  48
  49 static void
  50 object_state_change_free(ObjectStateChange *change)
  51 {
  52   if ((change) && (change->saved_state) && (change->saved_state->free))
  53     (*change->saved_state->free)(change->saved_state);
  54   g_free(change->saved_state);
  55 }
  56
  57 ObjectChange *new_object_state_change(DiaObject *obj,
  58                                       ObjectState *old_state,
  59                                       GetStateFunc get_state,
  60                                       SetStateFunc set_state )
  61 {
  62   ObjectStateChange *change;
  63
  64   change = g_new(ObjectStateChange, 1);
  65
  66   change->obj_change.apply =
  67     (ObjectChangeApplyFunc) object_state_change_apply_revert;
  68   change->obj_change.revert =
  69     (ObjectChangeRevertFunc) object_state_change_apply_revert;
  70   change->obj_change.free =
  71     (ObjectChangeFreeFunc) object_state_change_free;
  72
  73   change->get_state = get_state;
  74   change->set_state = set_state;
  75
  76   change->obj = obj;
  77   change->saved_state = old_state;
  78
  79   return (ObjectChange *)change;
  80 }
  81