[pango/avoid-overlong-lines: 4/6] Add pango_item_unsplit

[Matthias Clasen <matthiasc src gnome org>]

commit 88eacd0e3e8dc2b6230eb693df4b08d203a57450
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Nov 11 19:48:19 2021 -0500

    Add pango_item_unsplit
    
    This undoes the effect of pango_item_split.
    We will use this in future commits.
    Private for now.

 pango/pango-item-private.h |  4 ++++
 pango/pango-item.c         | 27 ++++++++++++++++++++++++++-
 2 files changed, 30 insertions(+), 1 deletion(-)
---
diff --git a/pango/pango-item-private.h b/pango/pango-item-private.h
index ef3e8ed0..d37fc3f8 100644
--- a/pango/pango-item-private.h
+++ b/pango/pango-item-private.h
@@ -88,6 +88,10 @@ GList *            pango_itemize_post_process_items   (PangoContext
                                                        PangoLogAttr               *log_attrs,
                                                        GList                      *items);
 
+void               pango_item_unsplit                 (PangoItem *orig,
+                                                       int        split_index,
+                                                       int        split_offset);
+
 
 G_END_DECLS
 
diff --git a/pango/pango-item.c b/pango/pango-item.c
index 4b02c277..2b2664c5 100644
--- a/pango/pango-item.c
+++ b/pango/pango-item.c
@@ -138,7 +138,7 @@ G_DEFINE_BOXED_TYPE (PangoItem, pango_item,
  * Return value: new item representing text before @split_index, which
  *   should be freed with [method Pango Item free].
  */
-PangoItem*
+PangoItem *
 pango_item_split (PangoItem *orig,
                   int        split_index,
                   int        split_offset)
@@ -164,6 +164,31 @@ pango_item_split (PangoItem *orig,
   return new_item;
 }
 
+/*< private >
+ * pango_item_unsplit:
+ * @orig: the item to unsplit
+ * @split_index: value passed to pango_item_split()
+ * @split_offset: value passed to pango_item_split()
+ *
+ * Undoes the effect of a pango_item_split() call with
+ * the same arguments.
+ *
+ * You are expected to free the new item that was returned
+ * by pango_item_split() yourself.
+ */
+void
+pango_item_unsplit (PangoItem *orig,
+                    int        split_index,
+                    int        split_offset)
+{
+  orig->offset -= split_index;
+  orig->length += split_index;
+  orig->num_chars += split_offset;
+
+  if (orig->analysis.flags & PANGO_ANALYSIS_FLAG_HAS_CHAR_OFFSET)
+    ((PangoItemPrivate *)orig)->char_offset -= split_offset;
+}
+
 static int
 compare_attr (gconstpointer p1, gconstpointer p2)
 {