[pango/simple-fontmap: 41/42] Add PangoCoreTextHbFontMap

[Matthias Clasen <matthiasc src gnome org>]

commit e39f3c1d98f332b2cdcb58d30d2950c16161a9a8
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Dec 28 23:29:11 2021 -0500

    Add PangoCoreTextHbFontMap
    
    This has not been seriously tested, but it compiles
    in ci, and produces a reasonably-looking font list
    and test png.

 pango/meson.build               |   1 +
 pango/pangocoretext-hbfontmap.c | 457 ++++++++++++++++++++++++++++++++++++++++
 pango/pangocoretext-hbfontmap.h |  37 ++++
 3 files changed, 495 insertions(+)
---
diff --git a/pango/meson.build b/pango/meson.build
index 1ebd7a1e..3be27319 100644
--- a/pango/meson.build
+++ b/pango/meson.build
@@ -545,6 +545,7 @@ if cairo_dep.found()
       'pangocoretext-fontmap.c',
       'pangocairo-coretextfont.c',
       'pangocairo-coretextfontmap.c',
+      'pangocoretext-hbfontmap.c',
     ]
   endif
 
diff --git a/pango/pangocoretext-hbfontmap.c b/pango/pangocoretext-hbfontmap.c
new file mode 100644
index 00000000..16144c24
--- /dev/null
+++ b/pango/pangocoretext-hbfontmap.c
@@ -0,0 +1,457 @@
+/* Pango
+ *
+ * Copyright (C) 2021 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "config.h"
+#include <math.h>
+
+#include <gio/gio.h>
+
+#include "pangocoretext-hbfontmap.h"
+#include "pango-hbfamily-private.h"
+#include "pango-hbfontmap-private.h"
+#include "pango-hbface-private.h"
+#include "pango-hbfont-private.h"
+#include "pango-context.h"
+#include "pango-impl-utils.h"
+#include "pango-trace-private.h"
+
+#include <Carbon/Carbon.h>
+#include <hb-ot.h>
+#include <hb-coretext.h>
+
+
+/**
+ * PangoCoreTextHbFontMap:
+ *
+ * `PangoCoreTextHbFontMap` is a subclass of `PangoHbFontMap` that uses
+ * CoreText to populate the fontmap with the available fonts.
+ */
+
+
+struct _PangoCoreTextHbFontMap
+{
+  PangoHbFontMap parent_instance;
+};
+
+struct _PangoCoreTextHbFontMapClass
+{
+  PangoHbFontMapClass parent_class;
+};
+
+/* {{{ CoreText utilities */
+
+#define ct_weight_min -0.7f
+#define ct_weight_max  0.8f
+
+/* This map is based on empirical data from analyzing a large collection of
+ * fonts and comparing the opentype value with the value that OSX returns.
+ * see: https://bugzilla.gnome.org/show_bug.cgi?id=766148
+ * FIXME: This need recalibrating, values outside these bounds do occur!
+ */
+
+static struct {
+  float ct_weight;
+  PangoWeight pango_weight;
+} ct_weight_map[] = {
+  { ct_weight_min,  PANGO_WEIGHT_THIN },
+  { -0.5,           PANGO_WEIGHT_ULTRALIGHT },
+  { -0.23,          PANGO_WEIGHT_LIGHT },
+  { -0.115,         PANGO_WEIGHT_SEMILIGHT },
+  {  0.00,          PANGO_WEIGHT_NORMAL },
+  {  0.2,           PANGO_WEIGHT_MEDIUM },
+  {  0.3,           PANGO_WEIGHT_SEMIBOLD },
+  {  0.4,           PANGO_WEIGHT_BOLD },
+  {  0.6,           PANGO_WEIGHT_ULTRABOLD },
+  {  ct_weight_max, PANGO_WEIGHT_HEAVY }
+};
+
+static int
+lerp (float x, float x1, float x2, int y1, int y2)
+{
+  float dx = x2 - x1;
+  int dy = y2 - y1;
+  return y1 + (dy * (x - x1) + dx / 2) / dx;
+}
+
+static PangoWeight
+ct_font_descriptor_get_weight (CTFontDescriptorRef desc)
+{
+  CFDictionaryRef dict;
+  CFNumberRef cf_number;
+  CGFloat value;
+  PangoWeight weight = PANGO_WEIGHT_NORMAL;
+  guint i;
+
+  dict = CTFontDescriptorCopyAttribute (desc, kCTFontTraitsAttribute);
+  cf_number = (CFNumberRef)CFDictionaryGetValue (dict, kCTFontWeightTrait);
+
+  if (cf_number != NULL && CFNumberGetValue (cf_number, kCFNumberCGFloatType, &value))
+    {
+    if (!(value >= ct_weight_min && value <= ct_weight_max))
+      {
+        i = value > ct_weight_max ? G_N_ELEMENTS (ct_weight_map) - 1 : 0;
+        weight = ct_weight_map[i].ct_weight;
+      }
+    else
+      {
+        for (i = 1; value > ct_weight_map[i].ct_weight; ++i)
+          ;
+
+        weight = lerp (value, ct_weight_map[i-1].ct_weight, ct_weight_map[i].ct_weight,
+                       ct_weight_map[i-1].pango_weight, ct_weight_map[i].pango_weight);
+
+      }
+    }
+  else
+    weight = PANGO_WEIGHT_NORMAL;
+
+  CFRelease (dict);
+
+  return weight;
+}
+
+static gchar *
+gchar_from_cf_string (CFStringRef str)
+{
+  CFIndex len;
+  gchar *buffer;
+
+  /* GetLength returns the number of UTF-16 pairs, so this number
+   * times 2 should definitely gives us enough space for UTF8.
+   * We add one for the terminating zero.
+   */
+  len = CFStringGetLength (str) * 2 + 1;
+  buffer = g_new0 (char, len);
+  CFStringGetCString (str, buffer, len, kCFStringEncodingUTF8);
+
+  return buffer;
+}
+
+static char *
+ct_font_descriptor_get_family_name (CTFontDescriptorRef desc,
+                                    gboolean            may_fail)
+{
+  CFStringRef cf_str;
+  char *buffer;
+
+  cf_str = CTFontDescriptorCopyAttribute (desc, kCTFontFamilyNameAttribute);
+  if (!cf_str)
+    {
+      int i;
+
+      /* No font family name is set, try to retrieve font name and deduce
+       * the family name from that instead.
+       */
+      cf_str = CTFontDescriptorCopyAttribute (desc, kCTFontNameAttribute);
+      if (!cf_str)
+        {
+          if (may_fail)
+            return NULL;
+
+          /* This font is likely broken, return a default family name ... */
+          return g_strdup ("Sans");
+        }
+
+      buffer = gchar_from_cf_string (cf_str);
+      CFRelease (cf_str);
+
+      for (i = 0; i < strlen (buffer); i++)
+        if (buffer[i] == '-')
+          break;
+
+      if (i < strlen (buffer))
+        {
+          char *ret;
+
+          ret = g_strndup (buffer, i);
+          g_free (buffer);
+
+          return ret;
+        }
+      else
+        return buffer;
+    }
+
+  buffer = gchar_from_cf_string (cf_str);
+  CFRelease (cf_str);
+
+  return buffer;
+}
+
+static char *
+ct_font_descriptor_get_style_name (CTFontDescriptorRef desc)
+{
+  CFStringRef cf_str;
+  char *buffer;
+
+  cf_str = CTFontDescriptorCopyAttribute (desc, kCTFontStyleNameAttribute);
+  if (!cf_str)
+    return NULL;
+
+  buffer = gchar_from_cf_string (cf_str);
+  CFRelease (cf_str);
+
+  return buffer;
+}
+
+static CTFontSymbolicTraits
+ct_font_descriptor_get_traits (CTFontDescriptorRef desc)
+{
+  CFDictionaryRef dict;
+  CFNumberRef cf_number;
+  SInt64 traits;
+
+  /* This is interesting, the value stored is a CTFontSymbolicTraits which
+   * is defined as uint32_t.  CFNumber does not have an obvious type which
+   * deals with unsigned values.  Upon inspection with CFNumberGetType,
+   * it turns out this value is stored as SInt64, so we use that to
+   * obtain the value from the CFNumber.
+   */
+  dict = CTFontDescriptorCopyAttribute (desc, kCTFontTraitsAttribute);
+  cf_number = (CFNumberRef)CFDictionaryGetValue (dict, kCTFontSymbolicTrait);
+  if (!CFNumberGetValue (cf_number, kCFNumberSInt64Type, &traits))
+    traits = 0;
+  CFRelease (dict);
+
+  return (CTFontSymbolicTraits)traits;
+}
+
+static gboolean
+ct_font_descriptor_is_small_caps (CTFontDescriptorRef desc)
+{
+  CFIndex i, count;
+  CFArrayRef array;
+  CFStringRef str;
+  gboolean retval = FALSE;
+
+  /* See http://stackoverflow.com/a/4811371 for why this works and an
+   * explanation of the magic number "3" used below.
+   */
+  array = CTFontDescriptorCopyAttribute (desc, kCTFontFeaturesAttribute);
+  if (!array)
+    return FALSE;
+
+  str = CFStringCreateWithCString (NULL, "CTFeatureTypeIdentifier",
+                                   kCFStringEncodingASCII);
+
+  count = CFArrayGetCount (array);
+  for (i = 0; i < count; i++)
+    {
+      CFDictionaryRef dict = CFArrayGetValueAtIndex (array, i);
+      CFNumberRef num;
+
+      num = (CFNumberRef)CFDictionaryGetValue (dict, str);
+      if (num)
+        {
+          int value = 0;
+
+          if (CFNumberGetValue (num, kCFNumberSInt32Type, &value) &&
+              value == 3)
+            {
+              /* This font supports small caps. */
+              retval = TRUE;
+              break;
+            }
+        }
+    }
+
+  CFRelease (str);
+  CFRelease (array);
+
+  return retval;
+}
+
+static gboolean
+pango_core_text_style_name_is_oblique (const char *style_name)
+{
+  return style_name && strstr (style_name, "Oblique");
+}
+
+static PangoFontDescription *
+font_description_from_ct_font_descriptor (CTFontDescriptorRef desc)
+{
+  SInt64 font_traits;
+  char *family_name;
+  char *style_name;
+  PangoFontDescription *font_desc;
+
+  font_desc = pango_font_description_new ();
+
+  family_name = ct_font_descriptor_get_family_name (desc, FALSE);
+  pango_font_description_set_family (font_desc, family_name);
+  g_free (family_name);
+
+  pango_font_description_set_weight (font_desc, ct_font_descriptor_get_weight (desc));
+
+  font_traits = ct_font_descriptor_get_traits (desc);
+  style_name = ct_font_descriptor_get_style_name (desc);
+
+  if ((font_traits & kCTFontItalicTrait) == kCTFontItalicTrait)
+    pango_font_description_set_style (font_desc, PANGO_STYLE_ITALIC);
+  else if (pango_core_text_style_name_is_oblique (style_name))
+    pango_font_description_set_style (font_desc, PANGO_STYLE_OBLIQUE);
+  else
+    pango_font_description_set_style (font_desc, PANGO_STYLE_NORMAL);
+
+  if ((font_traits & kCTFontCondensedTrait) == kCTFontCondensedTrait)
+    pango_font_description_set_stretch (font_desc, PANGO_STRETCH_CONDENSED);
+
+  if (ct_font_descriptor_is_small_caps (desc))
+    pango_font_description_set_variant (font_desc, PANGO_VARIANT_SMALL_CAPS);
+  else
+    pango_font_description_set_variant (font_desc, PANGO_VARIANT_NORMAL);
+
+  g_free (style_name);
+
+  return font_desc;
+}
+
+static PangoHbFace *
+face_from_ct_font_descriptor (CTFontDescriptorRef desc)
+{
+  PangoHbFace *face;
+  CTFontRef ctfont;
+  CGFontRef cgfont;
+  hb_face_t *hb_face;
+  char *name;
+  PangoFontDescription *description;
+
+  ctfont = CTFontCreateWithFontDescriptor (desc, 0.0, NULL);
+  cgfont = CTFontCopyGraphicsFont (ctfont, NULL);
+
+  hb_face = hb_coretext_face_create (cgfont);
+
+  CFRelease (cgfont);
+  CFRelease (ctfont);
+
+  name = ct_font_descriptor_get_style_name (desc);
+  description = font_description_from_ct_font_descriptor (desc);
+
+  hb_face_make_immutable (hb_face);
+
+  face = pango_hb_face_new_from_hb_face (hb_face, -1, name, description);
+  // FIXME: what about languages? see CTFontCopySupportedLanguages
+
+  pango_font_description_free (description);
+  g_free (name);
+  hb_face_destroy (hb_face);
+
+  return face;
+}
+
+/* }}} */
+/* {{{ PangoHbFontMap implementation */
+
+static void
+pango_core_text_hb_font_map_populate (PangoHbFontMap *map)
+{
+  PangoCoreTextHbFontMap *self = PANGO_CORE_TEXT_HB_FONT_MAP (map);
+  CTFontCollectionRef collection;
+  CFArrayRef ctfaces;
+  CFIndex count;
+
+  /* Add all system fonts */
+  collection = CTFontCollectionCreateFromAvailableFonts (0);
+  ctfaces = CTFontCollectionCreateMatchingFontDescriptors (collection);
+  count = CFArrayGetCount (ctfaces);
+
+  for (int i = 0; i < count; i++)
+    {
+      CTFontDescriptorRef desc = CFArrayGetValueAtIndex (ctfaces, i);
+      pango_hb_font_map_add_face (PANGO_HB_FONT_MAP (self), face_from_ct_font_descriptor (desc));
+    }
+
+  /* Add generic aliases */
+  struct {
+    const char *alias_name;
+    const char *family_name;
+  } aliases[] = {
+    { "monospace",  "Courier" },
+    { "sans-serif", "Helvetica" },
+    { "serif",      "Times" },
+    { "cursive",    "Apple Chancery" },
+    { "fantasy",    "Papyrus", },
+    { "system-ui",  ".AppleSystemUIFont" },
+    { "emoji",      "Apple Color Emoji" }
+  };
+
+  for (int i = 0; i < G_N_ELEMENTS (aliases); i++)
+    {
+      PangoFontFamily *family = pango_font_map_get_family (PANGO_FONT_MAP (map), aliases[i].family_name);
+
+      if (family)
+        {
+          PangoGenericFamily *alias_family;
+
+          alias_family = pango_generic_family_new (aliases[i].alias_name);
+          pango_generic_family_add_family (alias_family, family);
+          pango_hb_font_map_add_family (map, alias_family);
+    }
+}
+
+/* }}} */
+/* {{{ PangoFontMap implementation */
+
+G_DEFINE_TYPE (PangoCoreTextHbFontMap, pango_core_text_hb_font_map, PANGO_TYPE_HB_FONT_MAP)
+
+static void
+pango_core_text_hb_font_map_init (PangoCoreTextHbFontMap *self)
+{
+  pango_hb_font_map_repopulate (PANGO_HB_FONT_MAP (self), TRUE);
+}
+
+static void
+pango_core_text_hb_font_map_finalize (GObject *object)
+{
+  //PangoCoreTextHbFontMap *self = PANGO_CORE_TEXT_HB_FONT_MAP (object);
+
+  G_OBJECT_CLASS (pango_core_text_hb_font_map_parent_class)->finalize (object);
+}
+
+static void
+pango_core_text_hb_font_map_class_init (PangoCoreTextHbFontMapClass *class)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (class);
+  PangoHbFontMapClass *hb_font_map_class = PANGO_HB_FONT_MAP_CLASS (class);
+
+  object_class->finalize = pango_core_text_hb_font_map_finalize;
+
+  hb_font_map_class->populate = pango_core_text_hb_font_map_populate;
+}
+
+/* }}} */
+ /* {{{ Public API */
+
+/**
+ * pango_core_text_hb_font_map_new:
+ *
+ * Creates a new `PangoCoreTextHbFontMap` object.
+ *
+ * Returns: a new `PangoCoreTextcHbFontMap`
+ */
+PangoCoreTextHbFontMap *
+pango_core_text_hb_font_map_new (void)
+{
+  return g_object_new (PANGO_TYPE_CORE_TEXT_HB_FONT_MAP, NULL);
+}
+
+/* }}} */
+
+/* vim:set foldmethod=marker expandtab: */
diff --git a/pango/pangocoretext-hbfontmap.h b/pango/pangocoretext-hbfontmap.h
new file mode 100644
index 00000000..30f99dbd
--- /dev/null
+++ b/pango/pangocoretext-hbfontmap.h
@@ -0,0 +1,37 @@
+/* Pango
+ * pangocoretext-hbfontmap.h: Fontmap using coretext
+ *
+ * Copyright (C) 2021 Red Hat, Inc
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.         See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#pragma once
+
+#include <pango/pango.h>
+
+G_BEGIN_DECLS
+
+#define PANGO_TYPE_CORE_TEXT_HB_FONT_MAP      (pango_core_text_hb_font_map_get_type ())
+
+PANGO_AVAILABLE_IN_1_52
+PANGO_DECLARE_INTERNAL_TYPE (PangoCoreTextHbFontMap, pango_core_text_hb_font_map, PANGO, 
CORE_TEXT_HB_FONT_MAP, PangoHbFontMap)
+
+PANGO_AVAILABLE_IN_1_52
+PangoCoreTextHbFontMap * pango_core_text_hb_font_map_new (void);
+
+
+G_END_DECLS