[gtksourceview] Fix selection on redo

[Jesse van den Kieboom <jessevdk src gnome org>]

commit ee95815f8e450f107fcedd00351c16911ce03cea
Author: Jesse van den Kieboom <jessevdk gmail com>
Date:   Mon Apr 14 19:01:28 2014 +0200

    Fix selection on redo
    
    This fixes the selection on redo by storing the to-redo
    selection (i.e. current selection) on undo and vice versa.
    This keeps the selection state consistent with the selection
    whenever an undo/redo happens (since an undo can only be redone
    and vice versa)
    
    https://bugzilla.gnome.org/show_bug.cgi?id=672893

 gtksourceview/gtksourceundomanagerdefault.c |  138 +++++++++++++++++---------
 1 files changed, 90 insertions(+), 48 deletions(-)
---
diff --git a/gtksourceview/gtksourceundomanagerdefault.c b/gtksourceview/gtksourceundomanagerdefault.c
index 47c8bcd..adc0aa4 100644
--- a/gtksourceview/gtksourceundomanagerdefault.c
+++ b/gtksourceview/gtksourceundomanagerdefault.c
@@ -68,9 +68,6 @@ struct _GtkSourceUndoInsertAction
        gchar *text;
        gint   length;
        gint   chars;
-
-       gint   selection_start;
-       gint   selection_end;
 };
 
 struct _GtkSourceUndoDeleteAction
@@ -79,9 +76,6 @@ struct _GtkSourceUndoDeleteAction
        gint      end;
        gchar    *text;
        gboolean  forward;
-
-       gint      selection_start;
-       gint      selection_end;
 };
 
 struct _GtkSourceUndoAction
@@ -94,6 +88,9 @@ struct _GtkSourceUndoAction
                GtkSourceUndoDeleteAction  delete;
        } action;
 
+       gint selection_insert;
+       gint selection_bound;
+
        gint order_in_group;
 
        /* It is TRUE whether the action can be merged with the following action. */
@@ -473,23 +470,23 @@ gtk_source_undo_manager_can_redo_impl (GtkSourceUndoManager *manager)
 
 static void
 set_cursor (GtkTextBuffer *buffer,
-            gint           selection_start,
-            gint           selection_end)
+            gint           selection_insert,
+            gint           selection_bound)
 {
-       GtkTextIter start;
-       GtkTextIter end;
+       GtkTextIter insert_iter;
+       GtkTextIter bound_iter;
 
        /* Place the cursor at the requested position */
-       gtk_text_buffer_get_iter_at_offset (buffer, &start, selection_start);
+       gtk_text_buffer_get_iter_at_offset (buffer, &insert_iter, selection_insert);
 
-       if (selection_start == selection_end)
+       if (selection_insert == selection_bound)
        {
-               gtk_text_buffer_place_cursor (buffer, &start);
+               gtk_text_buffer_place_cursor (buffer, &insert_iter);
        }
        else
        {
-               gtk_text_buffer_get_iter_at_offset (buffer, &end, selection_end);
-               gtk_text_buffer_select_range (buffer, &start, &end);
+               gtk_text_buffer_get_iter_at_offset (buffer, &bound_iter, selection_bound);
+               gtk_text_buffer_select_range (buffer, &insert_iter, &bound_iter);
        }
 }
 
@@ -583,13 +580,57 @@ action_list_delete_last (GPtrArray *array)
 }
 
 static void
+selection_bounds_offsets (GtkTextBuffer *buffer,
+                          gint          *insert_offset,
+                          gint          *bound_offset)
+{
+       GtkTextIter insiter, seliter;
+       GtkTextMark *insmark, *selmark;
+
+       insmark = gtk_text_buffer_get_insert (buffer);
+       selmark = gtk_text_buffer_get_selection_bound (buffer);
+
+       gtk_text_buffer_get_iter_at_mark (buffer, &insiter, insmark);
+       gtk_text_buffer_get_iter_at_mark (buffer, &seliter, selmark);
+
+       *insert_offset = gtk_text_iter_get_offset (&insiter);
+       *bound_offset = gtk_text_iter_get_offset (&seliter);
+}
+
+static void
+selection_bounds_to_action (GtkTextBuffer       *buffer,
+                            GtkSourceUndoAction *undo_action)
+{
+       selection_bounds_offsets (buffer,
+                                 &undo_action->selection_insert,
+                                 &undo_action->selection_bound);
+}
+
+static void
+undo_action_swap_selection (GtkSourceUndoAction *action,
+                            gint                *selection_insert,
+                            gint                *selection_bound)
+{
+       gint insert_tmp, bound_tmp;
+
+       insert_tmp = *selection_insert;
+       bound_tmp = *selection_bound;
+
+       *selection_insert = action->selection_insert;
+       *selection_bound = action->selection_bound;
+
+       action->selection_insert = insert_tmp;
+       action->selection_bound = bound_tmp;
+}
+
+static void
 gtk_source_undo_manager_undo_impl (GtkSourceUndoManager *manager)
 {
        GtkSourceUndoManagerDefault *manager_default;
        GtkSourceUndoAction *undo_action;
        gboolean modified = FALSE;
-       gint selection_start = -1;
-       gint selection_end;
+       gint selection_insert;
+       gint selection_bound;
 
        manager_default = GTK_SOURCE_UNDO_MANAGER_DEFAULT (manager);
 
@@ -599,6 +640,11 @@ gtk_source_undo_manager_undo_impl (GtkSourceUndoManager *manager)
 
        gtk_source_undo_manager_begin_not_undoable_action (manager);
 
+       /* Initially obtain restored selection from the buffer. */
+       selection_bounds_offsets (manager_default->priv->buffer,
+                                 &selection_insert,
+                                 &selection_bound);
+
        do
        {
                undo_action = action_list_nth_data (manager_default->priv->actions,
@@ -619,6 +665,12 @@ gtk_source_undo_manager_undo_impl (GtkSourceUndoManager *manager)
                                    !manager_default->priv->modified_undoing_group);
                }
 
+               /* Swap the current selection into the action while obtaining
+                * the selection after undo from undo_action */
+               undo_action_swap_selection (undo_action,
+                                           &selection_insert,
+                                           &selection_bound);
+
                switch (undo_action->action_type)
                {
                        case GTK_SOURCE_UNDO_ACTION_DELETE:
@@ -626,9 +678,6 @@ gtk_source_undo_manager_undo_impl (GtkSourceUndoManager *manager)
                                             undo_action->action.delete.start,
                                             undo_action->action.delete.text,
                                             strlen (undo_action->action.delete.text));
-
-                               selection_start = undo_action->action.delete.selection_start;
-                               selection_end = undo_action->action.delete.selection_end;
                                break;
 
                        case GTK_SOURCE_UNDO_ACTION_INSERT:
@@ -636,9 +685,6 @@ gtk_source_undo_manager_undo_impl (GtkSourceUndoManager *manager)
                                             undo_action->action.insert.pos,
                                             undo_action->action.insert.pos +
                                             undo_action->action.insert.chars);
-
-                               selection_start = undo_action->action.insert.selection_start;
-                               selection_end = undo_action->action.insert.selection_end;
                                break;
 
                        default:
@@ -650,11 +696,11 @@ gtk_source_undo_manager_undo_impl (GtkSourceUndoManager *manager)
 
        } while (undo_action->order_in_group > 1);
 
-       if (selection_start >= 0)
+       if (selection_insert >= 0)
        {
                set_cursor (manager_default->priv->buffer,
-                           selection_start,
-                           selection_end);
+                           selection_insert,
+                           selection_bound);
        }
 
        if (modified)
@@ -688,13 +734,18 @@ gtk_source_undo_manager_redo_impl (GtkSourceUndoManager *manager)
        GtkSourceUndoManagerDefault *manager_default;
        GtkSourceUndoAction *undo_action;
        gboolean modified = FALSE;
-       gint selection_start = -1;
-       gint selection_end;
+       gint selection_insert;
+       gint selection_bound;
 
        manager_default = GTK_SOURCE_UNDO_MANAGER_DEFAULT (manager);
 
        g_return_if_fail (manager_default->priv->can_redo);
 
+       /* Initially obtain restored selection from the buffer. */
+       selection_bounds_offsets (manager_default->priv->buffer,
+                                 &selection_insert,
+                                 &selection_bound);
+
        undo_action = action_list_nth_data (manager_default->priv->actions,
                                            manager_default->priv->next_redo);
        g_return_if_fail (undo_action != NULL);
@@ -711,6 +762,12 @@ gtk_source_undo_manager_redo_impl (GtkSourceUndoManager *manager)
 
                --manager_default->priv->next_redo;
 
+               /* Swap the current selection into the action while obtaining
+                * the selection after undo from undo_action */
+               undo_action_swap_selection (undo_action,
+                                           &selection_insert,
+                                           &selection_bound);
+
                switch (undo_action->action_type)
                {
                        case GTK_SOURCE_UNDO_ACTION_DELETE:
@@ -718,15 +775,10 @@ gtk_source_undo_manager_redo_impl (GtkSourceUndoManager *manager)
                                             undo_action->action.delete.start,
                                             undo_action->action.delete.end);
 
-                               selection_start = undo_action->action.delete.selection_start;
-                               selection_end = undo_action->action.delete.selection_end;
 
                                break;
 
                        case GTK_SOURCE_UNDO_ACTION_INSERT:
-                               selection_start = undo_action->action.insert.selection_start;
-                               selection_end = undo_action->action.insert.selection_end;
-
                                insert_text (manager_default->priv->buffer,
                                             undo_action->action.insert.pos,
                                             undo_action->action.insert.text,
@@ -748,11 +800,11 @@ gtk_source_undo_manager_redo_impl (GtkSourceUndoManager *manager)
 
        } while ((undo_action != NULL) && (undo_action->order_in_group > 1));
 
-       if (selection_start >= 0)
+       if (selection_insert >= 0)
        {
                set_cursor (manager_default->priv->buffer,
-                           selection_start,
-                           selection_end);
+                           selection_insert,
+                           selection_bound);
        }
 
        if (modified)
@@ -841,14 +893,10 @@ insert_text_handler (GtkTextBuffer               *buffer,
                      GtkSourceUndoManagerDefault *manager)
 {
        GtkSourceUndoAction undo_action;
-       GtkTextIter selstart;
-       GtkTextIter selend;
 
        if (manager->priv->running_not_undoable_actions > 0)
                return;
 
-       gtk_text_buffer_get_selection_bounds (buffer, &selstart, &selend);
-
        undo_action.action_type = GTK_SOURCE_UNDO_ACTION_INSERT;
 
        undo_action.action.insert.pos    = gtk_text_iter_get_offset (pos);
@@ -856,8 +904,7 @@ insert_text_handler (GtkTextBuffer               *buffer,
        undo_action.action.insert.length = length;
        undo_action.action.insert.chars  = g_utf8_strlen (text, length);
 
-       undo_action.action.insert.selection_start = gtk_text_iter_get_offset (&selstart);
-       undo_action.action.insert.selection_end = gtk_text_iter_get_offset (&selend);
+       selection_bounds_to_action (buffer, &undo_action);
 
        if ((undo_action.action.insert.chars > 1) || (g_utf8_get_char (text) == '\n'))
 
@@ -878,14 +925,10 @@ delete_range_handler (GtkTextBuffer               *buffer,
 {
        GtkSourceUndoAction undo_action;
        GtkTextIter insert_iter;
-       GtkTextIter selstart;
-       GtkTextIter selend;
 
        if (um->priv->running_not_undoable_actions > 0)
                return;
 
-       gtk_text_buffer_get_selection_bounds (buffer, &selstart, &selend);
-
        undo_action.action_type = GTK_SOURCE_UNDO_ACTION_DELETE;
 
        gtk_text_iter_order (start, end);
@@ -898,8 +941,7 @@ delete_range_handler (GtkTextBuffer               *buffer,
                                                undo_action.action.delete.start,
                                                undo_action.action.delete.end);
 
-       undo_action.action.delete.selection_start = gtk_text_iter_get_offset (&selstart);
-       undo_action.action.delete.selection_end = gtk_text_iter_get_offset (&selend);
+       selection_bounds_to_action (buffer, &undo_action);
 
        /* figure out if the user used the Delete or the Backspace key */
        gtk_text_buffer_get_iter_at_mark (buffer, &insert_iter,