[5768] find_diff handle lines with control sequences better

[Gavin D. Smith]

Revision: 5768
          http://svn.sv.gnu.org/viewvc/?view=rev&root=texinfo&revision=5768
Author:   gavin
Date:     2014-08-21 15:22:10 +0000 (Thu, 21 Aug 2014)
Log Message:
-----------
find_diff handle lines with control sequences better

Modified Paths:
--------------
    trunk/ChangeLog
    trunk/info/display.c

Modified: trunk/ChangeLog
===================================================================
--- trunk/ChangeLog     2014-08-21 14:46:11 UTC (rev 5767)
+++ trunk/ChangeLog     2014-08-21 15:22:10 UTC (rev 5768)
@@ -3,6 +3,12 @@
        * info/display.c (decide_if_in_match): New function.
        (display_update_window_1): Call it.
 
+       * info/display.c (find_diff): Return offset of first ESC in line if
+       the lines differ and there is one.  Return -1 if no difference.
+       Handle multicolumn characters with wcwidth.
+       (display_node_text): Use offset into new line contents set by
+       find_diff.
+
 2014-08-21  Gavin Smith  <address@hidden>
 
        * info/infomap.c (default_emacs_like_info_keys): Add ESC x key

Modified: trunk/info/display.c
===================================================================
--- trunk/info/display.c        2014-08-21 14:46:11 UTC (rev 5767)
+++ trunk/info/display.c        2014-08-21 15:22:10 UTC (rev 5768)
@@ -95,23 +95,50 @@
   signal_unblock_winch ();
 }
 
+/* Return the screen column of where to write to screen to update line to
+   match A, given that B contains the current state of the line.  *PPOS gets
+   the offset into the string A to write from. */
 static int
 find_diff (const char *a, size_t alen, const char *b, size_t blen, int *ppos)
 {
   mbi_iterator_t itra, itrb;
   int i;
   int pos = 0;
+  int first_escape = -1;
+  int escape_pos = -1;
   
   for (i = 0, mbi_init (itra, a, alen), mbi_init (itrb, b, blen);
        mbi_avail (itra) && mbi_avail (itrb);
-       i++, mbi_advance (itra), mbi_advance (itrb))
+       i += wcwidth (itra.cur.wc), mbi_advance (itra), mbi_advance (itrb))
     {
       if (mb_cmp (mbi_cur (itra), mbi_cur (itrb)))
-       break;
+        break;
+
+      if (first_escape == -1 && *mbi_cur_ptr (itra) == '\033')
+        {
+          first_escape = i;
+          escape_pos = pos;
+        }
       pos += mb_len (mbi_cur (itra));
     }
-  *ppos = pos;
-  return i;
+
+  if (mbi_avail (itra) || mbi_avail (itrb))
+    if (first_escape != -1)
+      {
+        *ppos = escape_pos;
+        return first_escape;
+      }
+    else
+      {
+        /* If there was a difference in the line, and there was an escape
+           character, return the position of the escape character, as it could
+           start a terminal escape sequence. */
+        *ppos = pos;
+        return i;
+      }
+
+  /* Otherwise, no redrawing is required. */
+  return -1;
 }
 
 /* Update line PL_NUM of the screen to be PRINTED_LINE, which is PL_BYTES long
@@ -138,9 +165,7 @@
         the line from the screen first.  Why, I don't know.
         (But don't do this if we have no visible entries, as can
         happen if the window is shrunk very small.)  */
-      if (entry->inverse
-         /* Need to erase the line if it has escape sequences.  */
-         || (raw_escapes_p && mbschr (entry->text, '\033') != 0))
+      if (entry->inverse)
        {
          terminal_goto_xy (0, pl_num);
          terminal_clear_to_eol ();
@@ -152,15 +177,14 @@
       i = find_diff (printed_line, pl_bytes,
                     entry->text, strlen (entry->text), &off);
 
-      /* If the lines are not the same length, or if they differed
-        at all, we must do some redrawing. */
-      if (i != pl_chars || pl_chars != entry->textlen)
+      /* If the lines differed at all, we must do some redrawing. */
+      if (i != -1)
        {
          /* Move to the proper point on the terminal. */
          terminal_goto_xy (i, pl_num);
+
          /* If there is any text to print, print it. */
-         if (i != pl_chars)
-           terminal_put_text (printed_line + i);
+          terminal_put_text (printed_line + off);
          
          /* If the printed text didn't extend all the way to the edge
             of the screen, and text was appearing between here and the