[pango/visible-things: 6/12] fc: Implement showing ignorables

[Matthias Clasen <matthiasc src gnome org>]

commit ebe47ca4453c07e0ecc58c7edc8f35c6c2743074
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 | 40 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)
---
diff --git a/pango/pangofc-shape.c b/pango/pangofc-shape.c
index 27cdadf2..4e49dd05 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>
 
@@ -129,6 +130,15 @@ pango_hb_font_get_nominal_glyph (hb_font_t      *font,
 {
   PangoHbShapeContext *context = (PangoHbShapeContext *) font_data;
 
+  if (context->flags & PANGO_SHAPE_SHOW_IGNORABLES)
+    {
+      if (pango_get_ignorable (unicode))
+        {
+          *glyph = PANGO_GET_UNKNOWN_GLYPH (unicode);
+          return TRUE;
+        }
+    }
+
   if (hb_font_get_glyph (context->parent, unicode, 0, glyph))
     return TRUE;
 
@@ -181,6 +191,14 @@ pango_hb_font_get_glyph_advance (hb_font_t      *font,
 {
   PangoHbShapeContext *context = (PangoHbShapeContext *) font_data;
 
+  if (glyph & PANGO_GLYPH_UNKNOWN_FLAG)
+    {
+      PangoRectangle logical;
+
+      pango_font_get_glyph_extents (context->font, glyph, NULL, &logical);
+      return logical.width;
+    }
+
   return hb_font_get_glyph_h_advance (context->parent, glyph);
 }
 
@@ -193,6 +211,20 @@ pango_hb_font_get_glyph_extents (hb_font_t          *font,
 {
   PangoHbShapeContext *context = (PangoHbShapeContext *) font_data;
 
+  if (glyph & PANGO_GLYPH_UNKNOWN_FLAG)
+    {
+      PangoRectangle ink;
+
+      pango_font_get_glyph_extents (context->font, glyph, &ink, NULL);
+
+      extents->x_bearing = ink.x;
+      extents->y_bearing = ink.y;
+      extents->width     = ink.width;
+      extents->height    = ink.height;
+
+      return TRUE;
+    }
+
   return hb_font_get_glyph_extents (context->parent, glyph, extents);
 }
 
@@ -283,6 +315,7 @@ _pango_fc_shape (PangoFont           *font,
   PangoHbShapeContext context;
   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;
@@ -306,6 +339,11 @@ _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 (flags & PANGO_SHAPE_SHOW_IGNORABLES)
+    hb_buffer_flags |= HB_BUFFER_FLAG_PRESERVE_DEFAULT_IGNORABLES;
+
   /* setup buffer */
 
   hb_buffer_set_direction (hb_buffer, hb_direction);
@@ -314,7 +352,7 @@ _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);