src/history.c

   1 /*
   2  * This program is free software; you can redistribute it and/or
   3  * modify it under the terms of the GNU General Public License
   4  * as published by the Free Software Foundation; either version 2
   5  * of the License, or (at your option) any later version.
   6  *
   7  * This program is distributed in the hope that it will be useful,
   8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10  * GNU General Public License for more details.
  11  *
  12  * You should have received a copy of the GNU General Public License
  13  * along with this program; if not, write to the Free Software
  14  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  15  *
  16  * See the COPYING file for license information.
  17  *
  18  * Guillaume Chazarain <guichaz@yahoo.fr>
  19  */
  20
  21 /********************
  22  * History handling *
  23  ********************/
  24
  25 #include "gliv.h"
  26 #include "history.h"
  27 #include "options.h"
  28 #include "rendering.h"
  29 #include "matrix.h"
  30
  31 extern options_struct *options;
  32
  33 static GList *list = NULL;
  34 static GList *node = NULL;      /* Currrent position in the list. */
  35
  36 static gint count = 0;          /* Number of elements in the list. */
  37
  38 /* Returns item->next. */
  39 static GList *free_item(GList * item)
  40 {
  41     GList *next;
  42
  43     g_free(item->data);
  44     next = item->next;
  45     count--;
  46
  47     list = g_list_delete_link(list, item);
  48     return next;
  49 }
  50
  51 /* Free the elements from there to the end. */
  52 static void free_list(GList * item)
  53 {
  54     while (item != NULL)
  55         item = free_item(item);
  56 }
  57
  58 /* Keep the list from being larger than options->history_size. */
  59 void clean_history(void)
  60 {
  61     if (options->history_size < 0)
  62         /* Unlimited history. */
  63         return;
  64
  65     while (count > options->history_size) {
  66         if (node == list)
  67             node = node->next;
  68         list = free_item(list);
  69     }
  70
  71     if (list != NULL)
  72         list->prev = NULL;
  73 }
  74
  75 /* Add the current configuration to the end of the list. */
  76 void append_history(void)
  77 {
  78     GList *item;
  79
  80     if (options->history_size == 0)
  81         /* No history. */
  82         return;
  83
  84     item = g_list_alloc();
  85
  86     /* Fill the data. */
  87     item->data = new_matrix();
  88     matrix_cpy(item->data, NULL);
  89
  90     /* We are at the end of the list. */
  91     item->prev = node;
  92     item->next = NULL;
  93
  94     if (list == NULL)
  95         /* This is the first element. */
  96         list = item;
  97     else {
  98         if (node->next != NULL)
  99             /* We discard what was after us. */
 100             free_list(node->next);
 101
 102         node->next = item;
 103     }
 104
 105     node = item;
 106     count++;
 107     clean_history();
 108 }
 109
 110 static void set_state(GList * item)
 111 {
 112     if (item != NULL && item->data != NULL) {
 113         node = item;
 114         matrix_cpy(NULL, item->data);
 115         refresh(REFRESH_IMAGE | REFRESH_STATUS);
 116     }
 117 }
 118
 119 gboolean undo(void)
 120 {
 121     set_state(g_list_previous(node));
 122     return FALSE;
 123 }
 124
 125 gboolean redo(void)
 126 {
 127     set_state(g_list_next(node));
 128     return FALSE;
 129 }
 130
 131 /* Restart from scratch. */
 132 gboolean clear_history(void)
 133 {
 134     if (list != NULL) {
 135         free_list(list);
 136         list = node = NULL;
 137         append_history();
 138     }
 139
 140     return FALSE;
 141 }