[Emacs-diffs] emacs-24 a41d07b: Fix rendering of composed caharacters on the mode line. (Bug#19435)

[Eli Zaretskii]

branch: emacs-24
commit a41d07b329c034ad34e442bef93b6fcaeb556f9f
Author: Eli Zaretskii <address@hidden>
Commit: Eli Zaretskii <address@hidden>

    Fix rendering of composed caharacters on the mode line.  (Bug#19435)
    
     src/xdisp.c (set_iterator_to_next) <GET_FROM_STRING>: Limit search in
     composition_compute_stop_pos to the number of characters in the
     string.
     <GET_FROM_BUFFER, GET_FROM_STRING>: Simplify code.
     src/composite.c (composition_compute_stop_pos): If no composition
     was found in a string before ENDPOS, and ENDPOS is the string end,
     no need to back up to a safe point.
     src/dispextern.h (struct it) <end_charpos>: Improve commentary.
---
 src/ChangeLog    |   13 ++++
 src/composite.c  |    3 +-
 src/dispextern.h |    5 +-
 src/xdisp.c      |  171 +++++++++++++++++++++++------------------------------
 4 files changed, 93 insertions(+), 99 deletions(-)

diff --git a/src/ChangeLog b/src/ChangeLog
index 2840109..2df8308 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,16 @@
+2014-12-25  Eli Zaretskii  <address@hidden>
+
+       * xdisp.c (set_iterator_to_next) <GET_FROM_STRING>: Limit search in
+       composition_compute_stop_pos to the number of characters in the
+       string.  (Bug#19435)
+       <GET_FROM_BUFFER, GET_FROM_STRING>: Simplify code.
+
+       * composite.c (composition_compute_stop_pos): If no composition
+       was found in a string before ENDPOS, and ENDPOS is the string end,
+       no need to back up to a safe point.
+
+       * dispextern.h (struct it) <end_charpos>: Improve commentary.
+
 2014-12-24  Jan Djärv  <address@hidden>
 
        * nsimage.m (allocInitFromFile:): Initialize bmRep.
diff --git a/src/composite.c b/src/composite.c
index fa88214..a128210 100644
--- a/src/composite.c
+++ b/src/composite.c
@@ -1036,7 +1036,8 @@ composition_compute_stop_pos (struct composition_it 
*cmp_it, ptrdiff_t charpos,
                }
            }
        }
-      if (charpos == endpos)
+      if (charpos == endpos
+         && !(STRINGP (string) && endpos == SCHARS (string)))
        {
          /* We couldn't find a composition point before ENDPOS.  But,
             some character after ENDPOS may be composed with
diff --git a/src/dispextern.h b/src/dispextern.h
index 576f228..0e5a73a 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -2222,7 +2222,10 @@ struct it
   ptrdiff_t base_level_stop;
 
   /* Maximum string or buffer position + 1.  ZV when iterating over
-     current_buffer.  */
+     current_buffer.  When iterating over a string in display_string,
+     this can be smaller or greater than the number of string
+     characters, depending on the values of PRECISION and FIELD_WIDTH
+     with which display_string was called.  */
   ptrdiff_t end_charpos;
 
   /* C string to iterate over.  Non-null means get characters from
diff --git a/src/xdisp.c b/src/xdisp.c
index e3e0035..173df5d 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -7330,27 +7330,15 @@ set_iterator_to_next (struct it *it, int reseat_p)
       else if (it->cmp_it.id >= 0)
        {
          /* We are currently getting glyphs from a composition.  */
-         int i;
-
          if (! it->bidi_p)
            {
              IT_CHARPOS (*it) += it->cmp_it.nchars;
              IT_BYTEPOS (*it) += it->cmp_it.nbytes;
-             if (it->cmp_it.to < it->cmp_it.nglyphs)
-               {
-                 it->cmp_it.from = it->cmp_it.to;
-               }
-             else
-               {
-                 it->cmp_it.id = -1;
-                 composition_compute_stop_pos (&it->cmp_it, IT_CHARPOS (*it),
-                                               IT_BYTEPOS (*it),
-                                               it->end_charpos, Qnil);
-               }
            }
-         else if (! it->cmp_it.reversed_p)
+         else
            {
-             /* Composition created while scanning forward.  */
+             int i;
+
              /* Update IT's char/byte positions to point to the first
                 character of the next grapheme cluster, or to the
                 character visually after the current composition.  */
@@ -7358,52 +7346,34 @@ set_iterator_to_next (struct it *it, int reseat_p)
                bidi_move_to_visually_next (&it->bidi_it);
              IT_BYTEPOS (*it) = it->bidi_it.bytepos;
              IT_CHARPOS (*it) = it->bidi_it.charpos;
+           }
 
-             if (it->cmp_it.to < it->cmp_it.nglyphs)
-               {
-                 /* Proceed to the next grapheme cluster.  */
-                 it->cmp_it.from = it->cmp_it.to;
-               }
-             else
-               {
-                 /* No more grapheme clusters in this composition.
-                    Find the next stop position.  */
-                 ptrdiff_t stop = it->end_charpos;
-                 if (it->bidi_it.scan_dir < 0)
-                   /* Now we are scanning backward and don't know
-                      where to stop.  */
-                   stop = -1;
-                 composition_compute_stop_pos (&it->cmp_it, IT_CHARPOS (*it),
-                                               IT_BYTEPOS (*it), stop, Qnil);
-               }
+         if ((! it->bidi_p || ! it->cmp_it.reversed_p)
+             && it->cmp_it.to < it->cmp_it.nglyphs)
+           {
+             /* Composition created while scanning forward.  Proceed
+                to the next grapheme cluster.  */
+             it->cmp_it.from = it->cmp_it.to;
+           }
+         else if ((it->bidi_p && it->cmp_it.reversed_p)
+                  && it->cmp_it.from > 0)
+           {
+             /* Composition created while scanning backward.  Proceed
+                to the previous grapheme cluster.  */
+             it->cmp_it.to = it->cmp_it.from;
            }
          else
            {
-             /* Composition created while scanning backward.  */
-             /* Update IT's char/byte positions to point to the last
-                character of the previous grapheme cluster, or the
-                character visually after the current composition.  */
-             for (i = 0; i < it->cmp_it.nchars; i++)
-               bidi_move_to_visually_next (&it->bidi_it);
-             IT_BYTEPOS (*it) = it->bidi_it.bytepos;
-             IT_CHARPOS (*it) = it->bidi_it.charpos;
-             if (it->cmp_it.from > 0)
-               {
-                 /* Proceed to the previous grapheme cluster.  */
-                 it->cmp_it.to = it->cmp_it.from;
-               }
-             else
-               {
-                 /* No more grapheme clusters in this composition.
-                    Find the next stop position.  */
-                 ptrdiff_t stop = it->end_charpos;
-                 if (it->bidi_it.scan_dir < 0)
-                   /* Now we are scanning backward and don't know
-                      where to stop.  */
-                   stop = -1;
-                 composition_compute_stop_pos (&it->cmp_it, IT_CHARPOS (*it),
-                                               IT_BYTEPOS (*it), stop, Qnil);
-               }
+             /* No more grapheme clusters in this composition.
+                Find the next stop position.  */
+             ptrdiff_t stop = it->end_charpos;
+
+             if (it->bidi_it.scan_dir < 0)
+               /* Now we are scanning backward and don't know
+                  where to stop.  */
+               stop = -1;
+             composition_compute_stop_pos (&it->cmp_it, IT_CHARPOS (*it),
+                                           IT_BYTEPOS (*it), stop, Qnil);
            }
        }
       else
@@ -7532,61 +7502,63 @@ set_iterator_to_next (struct it *it, int reseat_p)
        }
       if (it->cmp_it.id >= 0)
        {
-         int i;
-
+         /* We are delivering display elements from a composition.
+            Update the string position past the grapheme cluster
+            we've just processed.  */
          if (! it->bidi_p)
            {
              IT_STRING_CHARPOS (*it) += it->cmp_it.nchars;
              IT_STRING_BYTEPOS (*it) += it->cmp_it.nbytes;
-             if (it->cmp_it.to < it->cmp_it.nglyphs)
-               it->cmp_it.from = it->cmp_it.to;
-             else
-               {
-                 it->cmp_it.id = -1;
-                 composition_compute_stop_pos (&it->cmp_it,
-                                               IT_STRING_CHARPOS (*it),
-                                               IT_STRING_BYTEPOS (*it),
-                                               it->end_charpos, it->string);
-               }
            }
-         else if (! it->cmp_it.reversed_p)
+         else
            {
+             int i;
+
              for (i = 0; i < it->cmp_it.nchars; i++)
                bidi_move_to_visually_next (&it->bidi_it);
              IT_STRING_BYTEPOS (*it) = it->bidi_it.bytepos;
              IT_STRING_CHARPOS (*it) = it->bidi_it.charpos;
+           }
 
-             if (it->cmp_it.to < it->cmp_it.nglyphs)
-               it->cmp_it.from = it->cmp_it.to;
-             else
-               {
-                 ptrdiff_t stop = it->end_charpos;
-                 if (it->bidi_it.scan_dir < 0)
-                   stop = -1;
-                 composition_compute_stop_pos (&it->cmp_it,
-                                               IT_STRING_CHARPOS (*it),
-                                               IT_STRING_BYTEPOS (*it), stop,
-                                               it->string);
-               }
+         /* Did we exhaust all the grapheme clusters of this
+            composition?  */
+         if ((! it->bidi_p || ! it->cmp_it.reversed_p)
+             && (it->cmp_it.to < it->cmp_it.nglyphs))
+           {
+             /* Not all the grapheme clusters were processed yet;
+                advance to the next cluster.  */
+             it->cmp_it.from = it->cmp_it.to;
+           }
+         else if ((it->bidi_p && it->cmp_it.reversed_p)
+                  && it->cmp_it.from > 0)
+           {
+             /* Likewise: advance to the next cluster, but going in
+                the reverse direction.  */
+             it->cmp_it.to = it->cmp_it.from;
            }
          else
            {
-             for (i = 0; i < it->cmp_it.nchars; i++)
-               bidi_move_to_visually_next (&it->bidi_it);
-             IT_STRING_BYTEPOS (*it) = it->bidi_it.bytepos;
-             IT_STRING_CHARPOS (*it) = it->bidi_it.charpos;
-             if (it->cmp_it.from > 0)
-               it->cmp_it.to = it->cmp_it.from;
-             else
+             /* This composition was fully processed; find the next
+                candidate place for checking for composed
+                characters.  */
+             /* Always limit string searches to the string length;
+                any padding spaces are not part of the string, and
+                there cannot be any compositions in that padding.  */
+             ptrdiff_t stop = SCHARS (it->string);
+
+             if (it->bidi_p && it->bidi_it.scan_dir < 0)
+               stop = -1;
+             else if (it->end_charpos < stop)
                {
-                 ptrdiff_t stop = it->end_charpos;
-                 if (it->bidi_it.scan_dir < 0)
-                   stop = -1;
-                 composition_compute_stop_pos (&it->cmp_it,
-                                               IT_STRING_CHARPOS (*it),
-                                               IT_STRING_BYTEPOS (*it), stop,
-                                               it->string);
+                 /* Cf. PRECISION in reseat_to_string: we might be
+                    limited in how many of the string characters we
+                    need to deliver.  */
+                 stop = it->end_charpos;
                }
+             composition_compute_stop_pos (&it->cmp_it,
+                                           IT_STRING_CHARPOS (*it),
+                                           IT_STRING_BYTEPOS (*it), stop,
+                                           it->string);
            }
        }
       else
@@ -7609,12 +7581,17 @@ set_iterator_to_next (struct it *it, int reseat_p)
              bidi_move_to_visually_next (&it->bidi_it);
              IT_STRING_BYTEPOS (*it) = it->bidi_it.bytepos;
              IT_STRING_CHARPOS (*it) = it->bidi_it.charpos;
+             /* If the scan direction changes, we may need to update
+                the place where to check for composed characters.  */
              if (prev_scan_dir != it->bidi_it.scan_dir)
                {
-                 ptrdiff_t stop = it->end_charpos;
+                 ptrdiff_t stop = SCHARS (it->string);
 
                  if (it->bidi_it.scan_dir < 0)
                    stop = -1;
+                 else if (it->end_charpos < stop)
+                   stop = it->end_charpos;
+
                  composition_compute_stop_pos (&it->cmp_it,
                                                IT_STRING_CHARPOS (*it),
                                                IT_STRING_BYTEPOS (*it), stop,