Fix bidi initialization in init_from_display_pos.

 src/xdisp.c (init_from_display_pos): Fix initialization of the bidi
 iterator when starting in the middle of a display or overlay
 string.

Fixes: debbugs:12745

2 files changed, 44 insertions, 0 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index e762eb13b8..8b7c1d9113 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,9 @@
+2012-11-03  Eli Zaretskii  <[email protected]>
+
+	* xdisp.c (init_from_display_pos): Fix initialization of the bidi
+	iterator when starting in the middle of a display or overlay
+	string.  (Bug#12745)
+
 2012-11-01  Eli Zaretskii  <[email protected]>
 
 	* w32proc.c (getpgrp, setpgid): New functions.  (Bug#12776)
diff --git a/src/xdisp.c b/src/xdisp.c
index b3b08edcd0..bc1cbd94bd 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -928,6 +928,7 @@ static enum move_it_result
        move_it_in_display_line_to (struct it *, ptrdiff_t, int,
 				   enum move_operation_enum);
 void move_it_vertically_backward (struct it *, int);
+static void get_visually_first_element (struct it *);
 static void init_to_row_start (struct it *, struct window *,
                                struct glyph_row *);
 static int init_to_row_end (struct it *, struct window *,
@@ -3113,6 +3114,40 @@ init_from_display_pos (struct it *it, struct window *w, struct display_pos *pos)
       eassert (STRINGP (it->string));
       it->current.string_pos = pos->string_pos;
       it->method = GET_FROM_STRING;
+      it->end_charpos = SCHARS (it->string);
+      /* Set up the bidi iterator for this overlay string.  */
+      if (it->bidi_p)
+	{
+	  it->bidi_it.string.lstring = it->string;
+	  it->bidi_it.string.s = NULL;
+	  it->bidi_it.string.schars = SCHARS (it->string);
+	  it->bidi_it.string.bufpos = it->overlay_strings_charpos;
+	  it->bidi_it.string.from_disp_str = it->string_from_display_prop_p;
+	  it->bidi_it.string.unibyte = !it->multibyte_p;
+	  bidi_init_it (IT_STRING_CHARPOS (*it), IT_STRING_BYTEPOS (*it),
+			FRAME_WINDOW_P (it->f), &it->bidi_it);
+
+	  /* Synchronize the state of the bidi iterator with
+	     pos->string_pos.  For any string position other than
+	     zero, this will be done automagically when we resume
+	     iteration over the string and get_visually_first_element
+	     is called.  But if string_pos is zero, and the string is
+	     to be reordered for display, we need to resync manually,
+	     since it could be that the iteration state recorded in
+	     pos ended at string_pos of 0 moving backwards in string.  */
+	  if (CHARPOS (pos->string_pos) == 0)
+	    {
+	      get_visually_first_element (it);
+	      if (IT_STRING_CHARPOS (*it) != 0)
+		do {
+		  /* Paranoia.  */
+		  eassert (it->bidi_it.charpos < it->bidi_it.string.schars);
+		  bidi_move_to_visually_next (&it->bidi_it);
+		} while (it->bidi_it.charpos != 0);
+	    }
+	  eassert (IT_STRING_CHARPOS (*it) == it->bidi_it.charpos
+		   && IT_STRING_BYTEPOS (*it) == it->bidi_it.bytepos);
+	}
     }
 
   if (CHARPOS (pos->string_pos) >= 0)
@@ -3122,6 +3157,9 @@ init_from_display_pos (struct it *it, struct window *w, struct display_pos *pos)
 	 IT should already be filled with that string.  */
       it->current.string_pos = pos->string_pos;
       eassert (STRINGP (it->string));
+      if (it->bidi_p)
+	bidi_init_it (IT_STRING_CHARPOS (*it), IT_STRING_BYTEPOS (*it),
+		      FRAME_WINDOW_P (it->f), &it->bidi_it);
     }
 
   /* Restore position in display vector translations, control