[pango/pango-1-44] Use shape flags for tab width

[Marco Trevisan <marcotrevi src gnome org>]

commit 04031036fb1b80a47c7030053f4767363935c068
Author: Jan Alexander Steffens (heftig) <jan steffens gmail com>
Date:   Tue Feb 11 03:51:19 2020 +0100

    Use shape flags for tab width
    
    We need to apply the right shape flags to the tab width calculation,
    otherwise (when glyph positions get rounded, which is the default) our
    tab width will be slightly off from what 8 spaces normally produce.
    
    https://gitlab.gnome.org/GNOME/pango/issues/425
    
    (cherry-picked from commit c579c0a9)

 pango/pango-layout.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
---
diff --git a/pango/pango-layout.c b/pango/pango-layout.c
index a1ebfbcc..16783941 100644
--- a/pango/pango-layout.c
+++ b/pango/pango-layout.c
@@ -3034,6 +3034,10 @@ ensure_tab_width (PangoLayout *layout)
       PangoAttrIterator *iter;
       PangoFontDescription *font_desc = pango_font_description_copy_static 
(pango_context_get_font_description (layout->context));
       PangoLanguage *language;
+      PangoShapeFlags shape_flags = PANGO_SHAPE_NONE;
+
+      if (pango_context_get_round_glyph_positions (layout->context))
+        shape_flags |= PANGO_SHAPE_ROUND_POSITIONS;
 
       layout_attrs = pango_layout_get_effective_attributes (layout);
       iter = pango_attr_list_get_iterator (layout_attrs);
@@ -3062,7 +3066,7 @@ ensure_tab_width (PangoLayout *layout)
       pango_attr_list_unref (tmp_attrs);
 
       item = items->data;
-      pango_shape ("        ", 8, &item->analysis, glyphs);
+      pango_shape_with_flags ("        ", 8, "        ", 8, &item->analysis, glyphs, shape_flags);
 
       pango_item_free (item);
       g_list_free (items);