lib/focus.c

   1 /* Dia -- a diagram creation/manipulation program
   2  * Copyright (C) 1998 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 /** This files handles which text elements are currently eligible to get
  20  * the input focus, and moving back and forth between them.  Objects can
  21  * add their texts to the list with request_focus (more than one can be
  22  * added), which doesn't give them focus outright, but makes them part of
  23  * the focus chain.  Actual handling of when focus goes where is handled
  24  * in app/disp_callbacks.c
  25  */
  26
  27 #include <config.h>
  28 #include "text.h"
  29 #include "focus.h"
  30
  31 static Focus *active_focus_ptr = NULL;
  32 static GList *text_foci = NULL;
  33
  34 /** Request that the give focus become active.
  35  * Also adds the focus to the list of available foci.
  36  * Eventually, this will only add the focus to the list. */
  37 void
  38 request_focus(Focus *focus)
  39 {
  40   /* Only add to focus list if not already there, and don't snatch focus. */
  41   if (!g_list_find(text_foci, focus)) {
  42     text_foci = g_list_append(text_foci, focus);
  43   }
  44   return;
  45   if (active_focus_ptr != NULL) {
  46     active_focus_ptr->has_focus = FALSE;
  47   }
  48   active_focus_ptr = focus;
  49   active_focus_ptr->has_focus = TRUE;
  50   text_foci = g_list_append(text_foci, focus);
  51 }
  52
  53 /** Return the currently active focus */
  54 Focus *
  55 active_focus(void)
  56 {
  57   return active_focus_ptr;
  58 }
  59
  60 void
  61 give_focus(Focus *focus)
  62 {
  63   if (active_focus_ptr != NULL) {
  64     active_focus_ptr->has_focus = FALSE;
  65   }
  66   active_focus_ptr = focus;
  67   active_focus_ptr->has_focus = TRUE;
  68 }
  69
  70 /* Return the first focus on the given object
  71  */
  72 Focus *
  73 focus_get_first_on_object(DiaObject *obj)
  74 {
  75   GList *tmplist = text_foci;
  76
  77   for (; tmplist != NULL; tmplist = g_list_next(tmplist) ) {
  78     Focus *focus = (Focus*)tmplist->data;
  79     if (focus_get_object(focus) == obj) {
  80       return focus;
  81     }
  82   }
  83   return NULL;
  84 }
  85
  86 /** Return the object that this focus belongs to.  Note that each
  87  * object may have more than one Text associated with it, the
  88  * focus will be on one of those.
  89  */
  90 DiaObject*
  91 focus_get_object(Focus *focus)
  92 {
  93   return focus->obj;
  94 }
  95
  96 /** Return the next available focus, if one is already active.
  97  */
  98 Focus *
  99 focus_next(void)
 100 {
 101   if (text_foci != NULL && active_focus_ptr != NULL) {
 102     GList *listelem = g_list_find(text_foci, active_focus_ptr);
 103     listelem = g_list_next(listelem);
 104     if (listelem == NULL) listelem = text_foci;
 105     return ((Focus*)listelem->data);
 106   }
 107   return NULL;
 108 }
 109
 110 /** Return the previous available focus, if one is already active.
 111  */
 112 Focus *
 113 focus_previous(void)
 114 {
 115   if (text_foci != NULL && active_focus_ptr != NULL) {
 116     GList *listelem = g_list_find(text_foci, active_focus_ptr);
 117     listelem = g_list_previous(listelem);
 118     if (listelem == NULL)
 119       listelem = g_list_last(text_foci);
 120     return (Focus *)listelem->data;
 121   }
 122   return NULL;
 123 }
 124
 125 /** Remove the current focus */
 126 void
 127 remove_focus(void)
 128 {
 129   if (active_focus_ptr != NULL) {
 130     active_focus_ptr->has_focus = FALSE;
 131   }
 132   active_focus_ptr = NULL;
 133 }
 134
 135 /** Reset the list of currently available foci */
 136 void
 137 reset_foci(void)
 138 {
 139   remove_focus();
 140   g_list_free(text_foci);
 141   text_foci = NULL;
 142 }
 143
 144 /** Removes all foci owned by the object.
 145  * Returns TRUE if the object had the active focus.
 146  */
 147 gboolean
 148 remove_focus_object(DiaObject *obj)
 149 {
 150   GList *tmplist = text_foci;
 151   gboolean active = FALSE;
 152
 153   for (; tmplist != NULL; ) {
 154     Focus *focus = (Focus*)tmplist->data;
 155     GList *link = tmplist;
 156     tmplist = g_list_next(tmplist);
 157     if (focus_get_object(focus) == obj) {
 158       text_foci = g_list_delete_link(text_foci, link);
 159       if (focus == active_focus_ptr) {
 160         active = TRUE;
 161       }
 162     }
 163   }
 164   return active;
 165 }