[pango/wip/kill-shape-engine: 22/30] Switch to using harfbuzz for shaping

[Matthias Clasen <matthiasc src gnome org>]

commit 1b614a25d6785d4a4b81a580df5952e68a7aecc4
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Jul 9 12:49:51 2019 -0400

    Switch to using harfbuzz for shaping
    
    Drop internal shape engine uses and call
    _pango_fc_shape directly. This makes us
    use harfbuzz for shaping, on all backends.

 pango/shape.c | 134 ++++++++++++++++++++++++++++++++--------------------------
 1 file changed, 73 insertions(+), 61 deletions(-)
---
diff --git a/pango/shape.c b/pango/shape.c
index 1d056f6c..9117138c 100644
--- a/pango/shape.c
+++ b/pango/shape.c
@@ -35,6 +35,8 @@
 #include "pango-glyph.h"
 #include "pango-engine-private.h"
 
+#include "pangofc-private.h"
+
 #include <string.h>
 
 /**
@@ -62,6 +64,55 @@ pango_shape (const gchar      *text,
   pango_shape_full (text, length, text, length, analysis, glyphs);
 }
 
+static void
+fallback_shape (const char          *text,
+                unsigned int         length,
+                const PangoAnalysis *analysis,
+                PangoGlyphString    *glyphs)
+{
+  int n_chars;
+  const char *p;
+  int cluster = 0;
+  int i;
+
+  n_chars = text ? pango_utf8_strlen (text, length) : 0;
+
+  pango_glyph_string_set_size (glyphs, n_chars);
+
+  p = text;
+  for (i = 0; i < n_chars; i++)
+    {
+      gunichar wc;
+      PangoGlyph glyph;
+      PangoRectangle logical_rect;
+
+      wc = g_utf8_get_char (p);
+
+      if (g_unichar_type (wc) != G_UNICODE_NON_SPACING_MARK)
+        cluster = p - text;
+
+      if (pango_is_zero_width (wc))
+        glyph = PANGO_GLYPH_EMPTY;
+      else
+        glyph = PANGO_GET_UNKNOWN_GLYPH (wc);
+
+      pango_font_get_glyph_extents (analysis->font, glyph, NULL, &logical_rect);
+
+      glyphs->glyphs[i].glyph = glyph;
+
+      glyphs->glyphs[i].geometry.x_offset = 0;
+      glyphs->glyphs[i].geometry.y_offset = 0;
+      glyphs->glyphs[i].geometry.width = logical_rect.width;
+
+      glyphs->log_clusters[i] = cluster;
+
+      p = g_utf8_next_char (p);
+    }
+
+  if (analysis->level & 1)
+    pango_glyph_string_reverse_range (glyphs, 0, glyphs->num_glyphs);
+}
+
 /**
  * pango_shape_full:
  * @item_text:        valid UTF-8 text to shape.
@@ -111,59 +162,42 @@ pango_shape_full (const gchar      *item_text,
   g_return_if_fail (paragraph_text <= item_text);
   g_return_if_fail (paragraph_text + paragraph_length >= item_text + item_length);
 
-  if (G_LIKELY (analysis->shape_engine && analysis->font))
+  if (analysis->font)
     {
-      _pango_engine_shape_shape (analysis->shape_engine, analysis->font,
-                                item_text, item_length,
-                                paragraph_text, paragraph_length,
-                                analysis, glyphs);
+      _pango_fc_shape (analysis->font,
+                       item_text, item_length,
+                       analysis, glyphs,
+                       paragraph_text, paragraph_length);
 
       if (G_UNLIKELY (glyphs->num_glyphs == 0))
        {
          /* If a font has been correctly chosen, but no glyphs are output,
-          * there's probably something wrong with the shaper, or the font.
+          * there's probably something wrong with the font.
           *
           * Trying to be informative, we print out the font description,
-          * shaper name, and the text, but to not flood the terminal with
+          * and the text, but to not flood the terminal with
           * zillions of the message, we set a flag to only err once per
-          * font/engine pair.
-          *
-          * To do the flag fast, we use the engine qname to qflag the font,
-          * but also the font description to flag the engine.  This is
-          * supposed to be fast to check, but also avoid writing out
-          * duplicate warnings when a new PangoFont is created.
+          * font.
           */
-         GType engine_type = G_OBJECT_TYPE (analysis->shape_engine);
-         GQuark warned_quark = g_type_qname (engine_type);
+          GQuark warned_quark = g_quark_from_static_string ("pango-shape-fail-warned");
 
          if (!g_object_get_qdata (G_OBJECT (analysis->font), warned_quark))
            {
-             PangoFontDescription *desc;
-             char *font_name;
-             const char *engine_name;
-
-             desc = pango_font_describe (analysis->font);
-             font_name = pango_font_description_to_string (desc);
-             pango_font_description_free (desc);
-
-             if (!g_object_get_data (G_OBJECT (analysis->shape_engine), font_name))
-               {
-                 engine_name = g_type_name (engine_type);
-                 if (!engine_name)
-                   engine_name = "(unknown)";
+              PangoFontDescription *desc;
+              char *font_name;
 
-                 g_warning ("shaping failure, expect ugly output. shape-engine='%s', font='%s', text='%.*s'",
-                            engine_name, font_name, item_length, item_text);
+              desc = pango_font_describe (analysis->font);
+              font_name = pango_font_description_to_string (desc);
+              pango_font_description_free (desc);
 
-                 g_object_set_data_full (G_OBJECT (analysis->shape_engine), font_name,
-                                         GINT_TO_POINTER (1), NULL);
-               }
+              g_warning ("shaping failure, expect ugly output. font='%s', text='%.*s'",
+                         font_name, item_length, item_text);
 
-             g_free (font_name);
+              g_free (font_name);
 
-             g_object_set_qdata_full (G_OBJECT (analysis->font), warned_quark,
-                                      GINT_TO_POINTER (1), NULL);
-           }
+              g_object_set_qdata (G_OBJECT (analysis->font), warned_quark,
+                                  GINT_TO_POINTER (1));
+            }
        }
     }
   else
@@ -171,12 +205,7 @@ pango_shape_full (const gchar      *item_text,
 
   if (G_UNLIKELY (!glyphs->num_glyphs))
     {
-      PangoEngineShape *fallback_engine = _pango_get_fallback_shaper ();
-
-      _pango_engine_shape_shape (fallback_engine, analysis->font,
-                                item_text, item_length,
-                                paragraph_text, paragraph_length,
-                                analysis, glyphs);
+      fallback_shape (item_text, item_length, analysis, glyphs);
       if (G_UNLIKELY (!glyphs->num_glyphs))
         return;
     }
@@ -210,24 +239,7 @@ pango_shape_full (const gchar      *item_text,
   if (G_UNLIKELY ((analysis->level & 1) &&
                  glyphs->log_clusters[0] < glyphs->log_clusters[glyphs->num_glyphs - 1]))
     {
-      /* Warn once per shaper */
-      static GQuark warned_quark = 0; /* MT-safe */
-
-      if (!warned_quark)
-       warned_quark = g_quark_from_static_string ("pango-shape-warned");
-
-      if (analysis->shape_engine && !g_object_get_qdata (G_OBJECT (analysis->shape_engine), warned_quark))
-       {
-         GType engine_type = G_OBJECT_TYPE (analysis->shape_engine);
-         const char *engine_name = g_type_name (engine_type);
-         if (!engine_name)
-           engine_name = "(unknown)";
-
-         g_warning ("Expected RTL run but shape-engine='%s' returned LTR. Fixing.", engine_name);
-
-         g_object_set_qdata_full (G_OBJECT (analysis->shape_engine), warned_quark,
-                                  GINT_TO_POINTER (1), NULL);
-       }
+      g_warning ("Expected RTL run but got LTR. Fixing.");
 
       /* *Fix* it so we don't crash later */
       pango_glyph_string_reverse_range (glyphs, 0, glyphs->num_glyphs);