From aa12788659f2a65314bdcc005d50105a5f4a63cd Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Fri, 21 Aug 2015 16:27:31 +0100
Subject: Improve justify_cluster() some more

Much better now.

Now I see issues in justify_words() again :(.
---
 pango/pango-layout.c | 55 ++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 40 insertions(+), 15 deletions(-)

diff --git a/pango/pango-layout.c b/pango/pango-layout.c
index a9241c1f..57e8e8f5 100644
--- a/pango/pango-layout.c
+++ b/pango/pango-layout.c
@@ -5188,6 +5188,11 @@ justify_clusters (PangoLayoutLine *line,
 
   for (mode = MEASURE; mode <= ADJUST; mode++)
     {
+      gboolean leftedge = TRUE;
+      PangoGlyphString *rightmost_glyphs = NULL;
+      int rightmost_space;
+      int residual = 0;
+
       added_so_far = 0;
       gaps_so_far = 0;
 
@@ -5197,9 +5202,10 @@ justify_clusters (PangoLayoutLine *line,
 	  PangoGlyphString *glyphs = run->glyphs;
 	  PangoGlyphItemIter cluster_iter;
 	  gboolean have_cluster;
+	  int dir;
 	  int offset;
-	  gboolean first_run = run_iter == line->runs;
-	  gboolean last_run = run_iter->next == NULL;
+
+	  dir = run->item->analysis.level % 2 == 0 ? +1 : -1;
 
 	  /* We need character offset of the start of the run.  We don't have this.
 	   * Compute by counting from the beginning of the line.  The naming is
@@ -5214,20 +5220,21 @@ justify_clusters (PangoLayoutLine *line,
 		 + pango_utf8_strlen (text + state->line_start_index,
 				      run->item->offset - state->line_start_index);
 
-	  for (have_cluster = pango_glyph_item_iter_init_start (&cluster_iter, run, text);
+	  for (have_cluster = dir > 0 ?
+		 pango_glyph_item_iter_init_start (&cluster_iter, run, text) :
+		 pango_glyph_item_iter_init_end   (&cluster_iter, run, text);
 	       have_cluster;
-	       have_cluster = pango_glyph_item_iter_next_cluster (&cluster_iter))
+	       have_cluster = dir > 0 ?
+	         pango_glyph_item_iter_next_cluster (&cluster_iter) :
+	         pango_glyph_item_iter_prev_cluster (&cluster_iter))
 	    {
 	      int i;
-	      int dir;
 	      int width = 0;
 
 	      /* don't expand in the middle of graphemes */
 	      if (!log_attrs[offset + cluster_iter.start_char].is_cursor_position)
 		continue;
 
-	      dir = (cluster_iter.start_glyph < cluster_iter.end_glyph) ? 1 : -1;
-
 	      for (i = cluster_iter.start_glyph; i != cluster_iter.end_glyph; i += dir)
 		width += glyphs->glyphs[i].geometry.width;
 
@@ -5242,9 +5249,13 @@ justify_clusters (PangoLayoutLine *line,
 		  int leftmost, rightmost;
 		  int adjustment, space_left, space_right;
 
-		  adjustment = ((gaps_so_far * total_remaining_width) - total_remaining_width/2) / total_gaps - added_so_far;
+		  adjustment = total_remaining_width / total_gaps + residual;
 		  if (is_hinted)
+		  {
+		    int old_adjustment = adjustment;
 		    adjustment = PANGO_UNITS_ROUND (adjustment);
+		    residual = old_adjustment - adjustment;
+		  }
 		  /* distribute to before/after */
 		  distribute_letter_spacing (adjustment, &space_left, &space_right);
 
@@ -5260,17 +5271,23 @@ justify_clusters (PangoLayoutLine *line,
 		    leftmost  = cluster_iter.end_glyph + 1;
 		    rightmost = cluster_iter.start_glyph;
 		  }
-		  /* Don't add to left-side of left-most glyph of left-most run. */
-		  if (!first_run || leftmost)
+		  /* Don't add to left-side of left-most glyph of left-most non-zero run. */
+		  if (leftedge)
+		    leftedge = FALSE;
+		  else
 		  {
-		    added_so_far += adjustment;
-		    glyphs->glyphs[leftmost ].geometry.width    += space_left ;
-		    glyphs->glyphs[leftmost ].geometry.x_offset += space_left ;
+		    glyphs->glyphs[leftmost].geometry.width    += space_left ;
+		    glyphs->glyphs[leftmost].geometry.x_offset += space_left ;
+		    added_so_far += space_left;
 		  }
-		  /* Don't add to right-side of right-most glyph of right-most run. */
-		  if (!last_run || rightmost != glyphs->num_glyphs - 1)
+		  /* Don't add to right-side of right-most glyph of right-most non-zero run. */
 		  {
+		    /* Save so we can undo later. */
+		    rightmost_glyphs = glyphs;
+		    rightmost_space = space_right;
+
 		    glyphs->glyphs[rightmost].geometry.width  += space_right;
+		    added_so_far += space_right;
 		  }
 		}
 	    }
@@ -5286,6 +5303,14 @@ justify_clusters (PangoLayoutLine *line,
 	      return;
 	    }
 	}
+      else /* mode == ADJUST */
+        {
+	  if (rightmost_glyphs)
+	   {
+	     rightmost_glyphs->glyphs[rightmost_glyphs->num_glyphs - 1].geometry.width -= rightmost_space;
+	     added_so_far -= rightmost_space;
+	   }
+	}
     }
 
   state->remaining_width -= added_so_far;
-- 
cgit v1.2.1