[pango/visible-things] Don't insert extra runs for hyphens

[Matthias Clasen <matthiasc src gnome org>]

commit ed5b0eb440af294f1d50f9606e6444af9291dab5
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Jul 15 20:58:13 2019 -0400

    Don't insert extra runs for hyphens
    
    Instead, reshape the pre-break run with the
    soft hyphen replaced by an actual hyphen.
    This is unfortunately inefficient, we copy
    the entire text for this. The alternative
    (scatter-gather populating the harfbuzz
    buffer) is too hard to manage.

 pango/pango-layout.c | 79 +++++++++++++++++++++++++++-------------------------
 1 file changed, 41 insertions(+), 38 deletions(-)
---
diff --git a/pango/pango-layout.c b/pango/pango-layout.c
index b66697c6..9688caac 100644
--- a/pango/pango-layout.c
+++ b/pango/pango-layout.c
@@ -3331,7 +3331,8 @@ should_ellipsize_current_line (PangoLayout    *layout,
 static PangoGlyphString *
 shape_run (PangoLayoutLine *line,
           ParaBreakState  *state,
-          PangoItem       *item)
+          PangoItem       *item,
+           gboolean         with_hyphen)
 {
   PangoLayout *layout = line->layout;
   PangoGlyphString *glyphs = pango_glyph_string_new ();
@@ -3345,9 +3346,30 @@ shape_run (PangoLayoutLine *line,
                            state->properties.shape_ink_rect, state->properties.shape_logical_rect,
                            glyphs);
       else
-       pango_shape_full (layout->text + item->offset, item->length,
-                         layout->text, layout->length,
-                         &item->analysis, glyphs);
+        {
+
+          if (with_hyphen)
+            {
+              GString *s = g_string_new ("");
+
+              g_string_append_len (s, layout->text, item->offset + item->length - 2);
+              g_string_append (s, "-");
+              g_string_append_len (s, layout->text + item->offset + item->length, layout->length - 
(item->offset + item->length));
+
+              pango_shape_full (s->str + item->offset, item->length - 1,
+                                s->str, s->len,
+                                &item->analysis, glyphs);
+
+              g_string_free (s, TRUE);
+
+            }
+          else
+            {
+              pango_shape_full (layout->text + item->offset, item->length,
+                                layout->text, layout->length,
+                                &item->analysis, glyphs);
+            }
+        }
 
       if (state->properties.letter_spacing)
        {
@@ -3377,7 +3399,8 @@ static void
 insert_run (PangoLayoutLine *line,
            ParaBreakState  *state,
            PangoItem       *run_item,
-           gboolean         last_run)
+           gboolean         last_run,
+            gboolean         with_hyphen)
 {
   PangoLayoutRun *run = g_slice_new (PangoLayoutRun);
 
@@ -3386,7 +3409,7 @@ insert_run (PangoLayoutLine *line,
   if (last_run && state->log_widths_offset == 0)
     run->glyphs = state->glyphs;
   else
-    run->glyphs = shape_run (line, state, run_item);
+    run->glyphs = shape_run (line, state, run_item, with_hyphen);
 
   if (last_run)
     {
@@ -3524,23 +3547,6 @@ find_break_extra_width (PangoLayout    *layout,
     return 0;
 }
 
-static void
-insert_hyphen_after (PangoLayoutLine *line,
-                     ParaBreakState  *state,
-                     PangoItem       *item)
-{
-  PangoLayout *layout = line->layout;
-  PangoLayoutRun *run;
-
-  /* Use the SHY as text for the hyphen run */
-  item->num_chars -= 1;
-  item->length -= 2;
-  run = create_hyphen_run (layout, item);
-  line->runs = g_slist_prepend (line->runs, run);
-
-  state->remaining_width -= pango_glyph_string_get_width (run->glyphs);
-}
-
 #if 0
 # define DEBUG debug
 void
@@ -3598,7 +3604,7 @@ process_item (PangoLayout     *layout,
   if (!state->glyphs)
     {
       pango_layout_get_item_properties (item, &state->properties);
-      state->glyphs = shape_run (line, state, item);
+      state->glyphs = shape_run (line, state, item, FALSE);
 
       state->log_widths = NULL;
       state->need_hyphen = NULL;
@@ -3611,7 +3617,7 @@ process_item (PangoLayout     *layout,
       g_utf8_get_char (layout->text + item->offset) == LINE_SEPARATOR &&
       !should_ellipsize_current_line (layout, state))
     {
-      insert_run (line, state, item, TRUE);
+      insert_run (line, state, item, TRUE, FALSE);
       state->log_widths_offset += item->num_chars;
 
       return BREAK_LINE_SEPARATOR;
@@ -3619,7 +3625,7 @@ process_item (PangoLayout     *layout,
 
   if (state->remaining_width < 0 && !no_break_at_end)  /* Wrapping off */
     {
-      insert_run (line, state, item, TRUE);
+      insert_run (line, state, item, TRUE, FALSE);
 
       return BREAK_ALL_FIT;
     }
@@ -3640,7 +3646,7 @@ process_item (PangoLayout     *layout,
     {
       state->remaining_width -= width;
       state->remaining_width = MAX (state->remaining_width, 0);
-      insert_run (line, state, item, TRUE);
+      insert_run (line, state, item, TRUE, FALSE);
 
       return BREAK_ALL_FIT;
     }
@@ -3715,10 +3721,9 @@ process_item (PangoLayout     *layout,
 
          if (break_num_chars == item->num_chars)
            {
-              gboolean insert_hyphen = break_needs_hyphen (layout, state, break_num_chars);
-             insert_run (line, state, item, TRUE);
-              if (insert_hyphen)
-                insert_hyphen_after (line, state, item);
+              gboolean hyphen;
+              hyphen = break_needs_hyphen (layout, state, break_num_chars);
+             insert_run (line, state, item, TRUE, hyphen);
 
              return BREAK_ALL_FIT;
            }
@@ -3729,26 +3734,24 @@ process_item (PangoLayout     *layout,
          else
            {
              PangoItem *new_item;
-              gboolean insert_hyphen = break_needs_hyphen (layout, state, break_num_chars);
+              gboolean hyphen;
 
              length = g_utf8_offset_to_pointer (layout->text + item->offset, break_num_chars) - 
(layout->text + item->offset);
 
              new_item = pango_item_split (item, length, break_num_chars);
 
+              hyphen = break_needs_hyphen (layout, state, break_num_chars);
              /* Add the width back, to the line, reshape, subtract the new width */
              state->remaining_width += break_width;
-             insert_run (line, state, new_item, FALSE);
+             insert_run (line, state, new_item, FALSE, hyphen);
              break_width = pango_glyph_string_get_width (((PangoGlyphItem *)(line->runs->data))->glyphs);
              state->remaining_width -= break_width;
 
+             state->log_widths_offset += break_num_chars;
+
              /* Shaped items should never be broken */
              g_assert (!shape_set);
 
-              if (insert_hyphen)
-                insert_hyphen_after (line, state, new_item);
-
-             state->log_widths_offset += break_num_chars;
-
              return BREAK_SOME_FIT;
            }
        }