[pango/matthiasc/for-main: 2/2] hyphen: Try harder to insert needed hyphens

[Matthias Clasen <matthiasc src gnome org>]

commit 33cf60ef132fed183964b47973470d0eaf391588
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Aug 25 19:39:43 2021 -0400

    hyphen: Try harder to insert needed hyphens
    
    We were forgetting to reshape runs in some situations,
    leading to them not having hyphens appended. This was
    happening when runs fit fully onto the end of a line
    that is wrapped anyway.

 pango/pango-layout.c | 47 +++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 43 insertions(+), 4 deletions(-)
---
diff --git a/pango/pango-layout.c b/pango/pango-layout.c
index ad56e8f9..6b14a5dd 100644
--- a/pango/pango-layout.c
+++ b/pango/pango-layout.c
@@ -3671,7 +3671,8 @@ insert_run (PangoLayoutLine *line,
 
   run->item = run_item;
 
-  if (last_run && state->log_widths_offset == 0)
+  if (last_run && state->log_widths_offset == 0 &&
+      !(run_item->analysis.flags & PANGO_ANALYSIS_FLAG_NEED_HYPHEN))
     run->glyphs = state->glyphs;
   else
     run->glyphs = shape_run (line, state, run_item);
@@ -5716,8 +5717,47 @@ zero_line_final_space (PangoLayoutLine *line,
 {
   PangoLayout *layout = line->layout;
   PangoItem *item = run->item;
-  PangoGlyphString *glyphs = run->glyphs;
-  int glyph = item->analysis.level % 2 ? 0 : glyphs->num_glyphs - 1;
+  PangoGlyphString *glyphs;
+  int glyph;
+  int line_chars;
+
+  line_chars = 0;
+  for (GSList *l = line->runs; l; l = l->next)
+    {
+      PangoLayoutRun *r = l->data;
+
+      if (r)
+        line_chars += r->item->num_chars;
+    }
+
+  if (layout->log_attrs[state->line_start_offset + line_chars].break_inserts_hyphen &&
+      !(item->analysis.flags & PANGO_ANALYSIS_FLAG_NEED_HYPHEN))
+    {
+      int width;
+      int start_offset;
+
+      /* The last run fit onto the line without breaking it, but it still needs a hyphen */
+
+      width = pango_glyph_string_get_width (run->glyphs);
+
+      /* Ugly, shape_run uses state->start_offset, so temporarily rewind things
+       * to the state before the run was inserted. Otherwise, we end up passing
+       * the wrong log attrs to the shaping machinery.
+       */
+      start_offset = state->start_offset;
+      state->start_offset = state->line_start_offset + line_chars - item->num_chars;
+
+      pango_glyph_string_free (run->glyphs);
+      item->analysis.flags |= PANGO_ANALYSIS_FLAG_NEED_HYPHEN;
+      run->glyphs = shape_run (line, state, item);
+
+      state->start_offset = start_offset;
+
+      state->remaining_width += pango_glyph_string_get_width (run->glyphs) - width;
+    }
+
+  glyphs = run->glyphs;
+  glyph = item->analysis.level % 2 ? 0 : glyphs->num_glyphs - 1;
 
   if (glyphs->glyphs[glyph].glyph == PANGO_GET_UNKNOWN_GLYPH (0x2028))
     return; /* this LS is visible */
@@ -5725,7 +5765,6 @@ zero_line_final_space (PangoLayoutLine *line,
   /* if the final char of line forms a cluster, and it's
    * a whitespace char, zero its glyph's width as it's been wrapped
    */
-
   if (glyphs->num_glyphs < 1 || state->start_offset == 0 ||
       !layout->log_attrs[state->start_offset - 1].is_white)
     return;