lib/objchange.h

   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 #ifndef CHANGE_H
  19 #define CHANGE_H
  20
  21 #include "diatypes.h"
  22
  23 typedef void (*ObjectChangeApplyFunc)(ObjectChange *change, Object *obj);
  24 typedef void (*ObjectChangeRevertFunc)(ObjectChange *change, Object *obj);
  25 typedef void (*ObjectChangeFreeFunc)(ObjectChange *change);
  26
  27 struct _ObjectChange {
  28   /* If apply == transaction_point_pointer then this is a transaction
  29      point */
  30   ObjectChangeApplyFunc  apply;
  31   ObjectChangeRevertFunc revert;
  32   ObjectChangeFreeFunc   free; /* Remove extra data. Then this object is freed */
  33 };
  34
  35 /******** Helper functions of objects: *************/
  36
  37 struct _ObjectState {
  38   void (*free)(ObjectState *state); /* Frees pointers in the state,
  39                                        not called if NULL */
  40 };
  41
  42 /*
  43   Gets the internal state from the object.
  44   This is used to snapshot the object state
  45   so that it can be stored for undo/redo.
  46
  47   Need not save state that only depens on
  48   the object and it's handles positions.
  49
  50   The calling function owns the returned reference.
  51 */
  52 typedef ObjectState * (*GetStateFunc) (Object* obj);
  53
  54 /*
  55   Sets the internal state from the object.
  56   This is used to snapshot the object state
  57   so that it can be stored for undo/redo.
  58
  59   The called function owns the reference and is
  60   responsible for freeing it.
  61 */
  62 typedef void (*SetStateFunc) (Object* obj, ObjectState *state);
  63
  64
  65 ObjectChange *new_object_state_change(Object *obj,
  66                                       ObjectState *old_state,
  67                                       GetStateFunc get_state,
  68                                       SetStateFunc set_state );
  69
  70 #endif /* CHANGE_H */
  71
  72