[pango] Fix pango_default_break function for sentence start/end

[Matthias Clasen <matthiasc src gnome org>]

commit 33c10cb0c40503630146e4d32de807728d99ab0c
Author: Peng Wu <alexepico gmail com>
Date:   Wed Aug 16 15:02:36 2017 +0800

    Fix pango_default_break function for sentence start/end
    
    Skip the space characters in sentence start/end.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=785978

 pango/break.c |   39 +++++++++++++++++++++++++++++----------
 1 files changed, 29 insertions(+), 10 deletions(-)
---
diff --git a/pango/break.c b/pango/break.c
index b92e768..34a7cd2 100644
--- a/pango/break.c
+++ b/pango/break.c
@@ -559,6 +559,7 @@ pango_default_break (const gchar   *text,
   gunichar base_character = 0;
 
   gint last_sentence_start = -1;
+  gint last_non_space = -1;
 
   gboolean almost_done = FALSE;
   gboolean done = FALSE;
@@ -1660,19 +1661,37 @@ pango_default_break (const gchar   *text,
        }
 
       /* ---- Sentence breaks ---- */
+      {
 
-      /* default to not a sentence start/end */
-      attrs[i].is_sentence_start = FALSE;
-      attrs[i].is_sentence_end = FALSE;
+       /* default to not a sentence start/end */
+       attrs[i].is_sentence_start = FALSE;
+       attrs[i].is_sentence_end = FALSE;
 
-      if (last_sentence_start == -1 && !is_sentence_boundary) {
-       last_sentence_start = i - 1;
-       attrs[i - 1].is_sentence_start = TRUE;
-      }
+       /* maybe start sentence */
+       if (last_sentence_start == -1 && !is_sentence_boundary)
+         last_sentence_start = i - 1;
+
+       /* remember last non space character position */
+       if (i > 0 && !attrs[i - 1].is_white)
+         last_non_space = i;
+
+       /* meets sentence end, mark both sentence start and end */
+       if (last_sentence_start != -1 && is_sentence_boundary) {
+         if (last_non_space != -1) {
+           attrs[last_sentence_start].is_sentence_start = TRUE;
+           attrs[last_non_space].is_sentence_end = TRUE;
+         }
+
+         last_sentence_start = -1;
+         last_non_space = -1;
+       }
+
+       /* meets space character, move sentence start */
+       if (last_sentence_start != -1 &&
+           last_sentence_start == i - 1 &&
+           attrs[i - 1].is_white)
+           last_sentence_start++;
 
-      if (last_sentence_start != -1 && is_sentence_boundary) {
-       last_sentence_start = -1;
-       attrs[i].is_sentence_end = TRUE;
       }
 
       prev_wc = wc;