[pango/visible-things: 9/13] fc: Implement showing ignorables

[Matthias Clasen <matthiasc src gnome org>]

commit 269a3ae63fa998a0471593b108be824ea1468c57
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Jul 7 14:11:56 2019 -0400

    fc: Implement showing ignorables
    
    We tell harfbuzz to preserve the ignorables in
    shaping output, and use our glyph lookup to turn
    them into unknown glyphs that we can shape into
    custom hex boxes.

 pango/pangofc-shape.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)
---
diff --git a/pango/pangofc-shape.c b/pango/pangofc-shape.c
index 12a0f072..3e9502ff 100644
--- a/pango/pangofc-shape.c
+++ b/pango/pangofc-shape.c
@@ -29,6 +29,7 @@
 #include "pangofc-private.h"
 #include "pangofc-font-private.h"
 #include "pangofc-fontmap-private.h"
+#include "pango-impl-utils.h"
 #include <hb-ft.h>
 #include <hb-glib.h>
 
@@ -87,6 +88,15 @@ pango_fc_hb_font_get_nominal_glyph (hb_font_t *font, void *font_data,
   PangoFcHbContext *context = (PangoFcHbContext *) font_data;
   PangoFcFont *fc_font = context->fc_font;
 
+  if (context->shape_flags & PANGO_SHAPE_SHOW_IGNORABLES)
+    {
+      if (pango_get_ignorable (unicode))
+        {
+          *glyph = PANGO_GET_UNKNOWN_GLYPH (unicode);
+          return TRUE;
+        }
+    }
+
   *glyph = pango_fc_font_get_glyph (fc_font, unicode);
   if (G_LIKELY (*glyph))
     return TRUE;
@@ -330,6 +340,7 @@ _pango_fc_shape (PangoFont           *font,
   hb_face_t *hb_face;
   hb_font_t *hb_font;
   hb_buffer_t *hb_buffer;
+  hb_buffer_flags_t hb_buffer_flags;
   hb_direction_t hb_direction;
   gboolean free_buffer;
   hb_glyph_info_t *hb_glyph;
@@ -412,6 +423,11 @@ _pango_fc_shape (PangoFont           *font,
   if (PANGO_GRAVITY_IS_IMPROPER (analysis->gravity))
     hb_direction = HB_DIRECTION_REVERSE (hb_direction);
 
+  hb_buffer_flags = HB_BUFFER_FLAG_BOT | HB_BUFFER_FLAG_EOT;
+
+  if (shape_flags & PANGO_SHAPE_SHOW_IGNORABLES)
+    hb_buffer_flags |= HB_BUFFER_FLAG_PRESERVE_DEFAULT_IGNORABLES;
+
   /* setup buffer */
 
   hb_buffer_set_direction (hb_buffer, hb_direction);
@@ -420,7 +436,7 @@ _pango_fc_shape (PangoFont           *font,
 #if HB_VERSION_ATLEAST(1,0,3)
   hb_buffer_set_cluster_level (hb_buffer, HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS);
 #endif
-  hb_buffer_set_flags (hb_buffer, HB_BUFFER_FLAG_BOT | HB_BUFFER_FLAG_EOT);
+  hb_buffer_set_flags (hb_buffer, hb_buffer_flags);
 
   hb_buffer_add_utf8 (hb_buffer, paragraph_text, paragraph_length, item_offset, item_length);