Re: visual-line-mode

[Chong Yidong <cyd@stupidchicken.com>]

Could someone please test the following patch to xdisp.c?  It should fix
some bugs in the word-wrapping code, but there are probably still
lurking issues.


*** trunk/src/xdisp.c.~1.1227.~	2008-07-03 11:54:01.000000000 -0400
--- trunk/src/xdisp.c	2008-07-03 15:16:08.000000000 -0400
***************
*** 6664,6670 ****
  {
    enum move_it_result result = MOVE_UNDEFINED;
    struct glyph_row *saved_glyph_row;
!   struct it wrap_it, atpos_it;
    int may_wrap = 0;
  
    /* Don't produce glyphs in produce_glyphs.  */
--- 6664,6670 ----
  {
    enum move_it_result result = MOVE_UNDEFINED;
    struct glyph_row *saved_glyph_row;
!   struct it wrap_it, atpos_it, atx_it;
    int may_wrap = 0;
  
    /* Don't produce glyphs in produce_glyphs.  */
***************
*** 6672,6682 ****
    it->glyph_row = NULL;
  
    /* Use wrap_it to save a copy of IT wherever a word wrap could
!      occur.  Use atpos_it to save a copy of IT at the desired
       position, if found, so that we can scan ahead and check if the
!      word later overshoots the window edge.  */
    wrap_it.sp = -1;
    atpos_it.sp = -1;
  
  #define BUFFER_POS_REACHED_P()					\
    ((op & MOVE_TO_POS) != 0					\
--- 6672,6684 ----
    it->glyph_row = NULL;
  
    /* Use wrap_it to save a copy of IT wherever a word wrap could
!      occur.  Use atpos_it to save a copy of IT at the desired buffer
       position, if found, so that we can scan ahead and check if the
!      word later overshoots the window edge.  Use atx_it similarly, for
!      pixel positions.  */
    wrap_it.sp = -1;
    atpos_it.sp = -1;
+   atx_it.sp = -1;
  
  #define BUFFER_POS_REACHED_P()					\
    ((op & MOVE_TO_POS) != 0					\
***************
*** 6705,6718 ****
  	{
  	  if (it->line_wrap == WORD_WRAP)
  	    {
- 	      /* If wrap_it is valid, the current position might be in
- 		 a word that is wrapped to the next line, so continue
- 		 to see if that happens.  */
  	      if (wrap_it.sp < 0)
  		{
  		  result = MOVE_POS_MATCH_OR_ZV;
  		  break;
  		}
  	      if (atpos_it.sp < 0)
  		atpos_it = *it;
  	    }
--- 6707,6720 ----
  	{
  	  if (it->line_wrap == WORD_WRAP)
  	    {
  	      if (wrap_it.sp < 0)
  		{
  		  result = MOVE_POS_MATCH_OR_ZV;
  		  break;
  		}
+ 	      /* If wrap_it is valid, the current position might be in
+ 		 a word that is wrapped to the next line, so continue
+ 		 to see if that happens.  */
  	      if (atpos_it.sp < 0)
  		atpos_it = *it;
  	    }
***************
*** 6759,6766 ****
  		  if (atpos_it.sp >= 0)
  		    {
  		      *it = atpos_it;
! 		      atpos_it.sp = -1;
! 		      goto buffer_pos_reached;
  		    }
  		  wrap_it = *it;
  		  may_wrap = 0;
--- 6761,6774 ----
  		  if (atpos_it.sp >= 0)
  		    {
  		      *it = atpos_it;
! 		      result = MOVE_POS_MATCH_OR_ZV;
! 		      goto done;
! 		    }
! 		  if (atx_it.sp >= 0)
! 		    {
! 		      *it = atx_it;
! 		      result = MOVE_X_REACHED;
! 		      goto done;
  		    }
  		  wrap_it = *it;
  		  may_wrap = 0;
***************
*** 6816,6836 ****
  	      /* We want to leave anything reaching TO_X to the caller.  */
  	      if ((op & MOVE_TO_X) && new_x > to_x)
  		{
! 		  if (BUFFER_POS_REACHED_P ())
  		    {
! 		      if (it->line_wrap == WORD_WRAP)
  			{
  			  if (wrap_it.sp < 0)
  			    goto buffer_pos_reached;
! 			  if (atpos_it.sp < 0)
  			    atpos_it = *it;
  			}
! 		      else
  			goto buffer_pos_reached;
  		    }
- 		  it->current_x = x;
- 		  result = MOVE_X_REACHED;
- 		  break;
  		}
  
  	      if (/* Lines are continued.  */
--- 6824,6858 ----
  	      /* We want to leave anything reaching TO_X to the caller.  */
  	      if ((op & MOVE_TO_X) && new_x > to_x)
  		{
! 		  if (it->line_wrap == WORD_WRAP)
  		    {
! 		      if (BUFFER_POS_REACHED_P ())
  			{
  			  if (wrap_it.sp < 0)
  			    goto buffer_pos_reached;
! 			  else if (atpos_it.sp < 0)
  			    atpos_it = *it;
  			}
! 		      else if (wrap_it.sp < 0)
! 			{
! 			  it->current_x = x;
! 			  result = MOVE_X_REACHED;
! 			  break;
! 			}
! 		      else if (atx_it.sp < 0)
! 			{
! 			  atx_it = *it;
! 			  atx_it.current_x = x;
! 			}
! 		    }
! 		  else
! 		    {
! 		      if (BUFFER_POS_REACHED_P ())
  			goto buffer_pos_reached;
+ 		      it->current_x = x;
+ 		      result = MOVE_X_REACHED;
+ 		      break;
  		    }
  		}
  
  	      if (/* Lines are continued.  */
***************
*** 6840,6852 ****
  		      /* Or it fits exactly and we're on a window
  			 system frame.  */
  		      || (new_x == it->last_visible_x
! 			  && FRAME_WINDOW_P (it->f))))
  		{
  		  if (/* IT->hpos == 0 means the very first glyph
  			 doesn't fit on the line, e.g. a wide image.  */
  		      it->hpos == 0
  		      || (new_x == it->last_visible_x
! 			  && FRAME_WINDOW_P (it->f)))
  		    {
  		      ++it->hpos;
  		      it->current_x = new_x;
--- 6862,6876 ----
  		      /* Or it fits exactly and we're on a window
  			 system frame.  */
  		      || (new_x == it->last_visible_x
! 			  && FRAME_WINDOW_P (it->f)
! 			  && it->line_wrap == WINDOW_WRAP)))
  		{
  		  if (/* IT->hpos == 0 means the very first glyph
  			 doesn't fit on the line, e.g. a wide image.  */
  		      it->hpos == 0
  		      || (new_x == it->last_visible_x
! 			  && FRAME_WINDOW_P (it->f)
! 			  && it->line_wrap == WINDOW_WRAP))
  		    {
  		      ++it->hpos;
  		      it->current_x = new_x;
***************
*** 6903,6908 ****
--- 6927,6933 ----
  		    {
  		      *it = wrap_it;
  		      atpos_it.sp = -1;
+ 		      atx_it.sp = -1;
  		    }
  
  		  TRACE_MOVE ((stderr, "move_it_in: continued at %d\n",
***************
*** 6995,7003 ****
  #undef BUFFER_POS_REACHED_P
  
    /* If we scanned beyond to_pos and didn't find a point to wrap at,
!      return iterator at to_pos.  */
    if (atpos_it.sp >= 0)
      *it = atpos_it;
  
    /* Restore the iterator settings altered at the beginning of this
       function.  */
--- 7020,7032 ----
  #undef BUFFER_POS_REACHED_P
  
    /* If we scanned beyond to_pos and didn't find a point to wrap at,
!      restore the saved iterator.  */
    if (atpos_it.sp >= 0)
      *it = atpos_it;
+   else if (atx_it.sp >= 0)
+     *it = atx_it;
+ 
+  done:
  
    /* Restore the iterator settings altered at the beginning of this
       function.  */
***************
*** 16622,16628 ****
  				}
  			    }
  #endif /* HAVE_WINDOW_SYSTEM */
! 			  if (wrap_row_used > 0)
  			    goto back_to_wrap;
  			}
  		    }
--- 16651,16667 ----
  				}
  			    }
  #endif /* HAVE_WINDOW_SYSTEM */
! 
! 			  /* If line-wrap is on, consider returning to
! 			     a previously set wrap point, if there is
! 			     one.  Be sure to handle the case where
! 			     the last character on the line is a
! 			     space, as well as the case where the
! 			     following character is also a space.  */
! 			  if (wrap_row_used > 0
! 			      && (!may_wrap
! 				  || (it->what == IT_CHARACTER
! 				      && (it->c == ' ' || it->c == '\t'))))
  			    goto back_to_wrap;
  			}
  		    }