[pango/simple-fontmap: 4/15] Add PangoHbFace

[Matthias Clasen <matthiasc src gnome org>]

commit 0b8a62ea3dff6bbba7ca19062c045d1f28443fff
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Oct 29 19:18:27 2021 -0400

    Add PangoHbFace
    
    PangoHbFace is a simple wrapper around hb_face_t.
    
    This is an attempt to make a font backend that does
    not depend on platform specifics and can be used in
    tests.

 pango/meson.build            |   2 +
 pango/pango-hbface-private.h |  33 ++++
 pango/pango-hbface.c         | 460 +++++++++++++++++++++++++++++++++++++++++++
 pango/pango-hbface.h         |  50 +++++
 pango/pango.h                |   1 +
 5 files changed, 546 insertions(+)
---
diff --git a/pango/meson.build b/pango/meson.build
index 084de229..381ee155 100644
--- a/pango/meson.build
+++ b/pango/meson.build
@@ -27,6 +27,7 @@ pango_sources = [
   'pango-utils.c',
   'reorder-items.c',
   'shape.c',
+  'pango-hbface.c',
 ]
 
 pango_headers = [
@@ -56,6 +57,7 @@ pango_headers = [
   'pango-tabs.h',
   'pango-types.h',
   'pango-utils.h',
+  'pango-hbface.h',
 ]
 
 pango_installed_headers = pango_headers + [ 'pango-version-macros.h' ]
diff --git a/pango/pango-hbface-private.h b/pango/pango-hbface-private.h
new file mode 100644
index 00000000..6636ec7b
--- /dev/null
+++ b/pango/pango-hbface-private.h
@@ -0,0 +1,33 @@
+#pragma once
+
+#include "pango-hbface.h"
+#include "pango-fontmap.h"
+#include <hb.h>
+
+struct _PangoHbFace
+{
+  PangoFontFace parent_instance;
+
+  hb_face_t *face;
+  char *name;
+  PangoFontFamily *family;
+  PangoFontDescription *description;
+  PangoMatrix matrix;
+  double x_scale, y_scale;
+  PangoLanguage **languages;
+  gboolean synthetic;
+
+  PangoFontMap *map;
+};
+
+void            pango_hb_face_set_font_map      (PangoHbFace          *self,
+                                                 PangoFontMap         *map);
+void            pango_hb_face_set_family        (PangoHbFace          *self,
+                                                 PangoFontFamily      *family);
+
+gboolean        pango_hb_face_is_monospace      (PangoHbFace          *self);
+gboolean        pango_hb_face_is_variable       (PangoHbFace          *self);
+PangoLanguage **pango_hb_face_get_languages     (PangoHbFace          *self);
+void            pango_hb_face_set_languages     (PangoHbFace          *self,
+                                                 const PangoLanguage **languages,
+                                                 gsize                 n_languages);
diff --git a/pango/pango-hbface.c b/pango/pango-hbface.c
new file mode 100644
index 00000000..cf7b5f13
--- /dev/null
+++ b/pango/pango-hbface.c
@@ -0,0 +1,460 @@
+/* Pango
+ *
+ * Copyright (C) 2021 Matthias Clasen
+ *
+ * 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 "pango-hbface-private.h"
+
+#include <hb-ot.h>
+
+/* {{{ PangoFontFace implementation */
+
+struct _PangoHbFaceClass
+{
+  PangoFontFaceClass parent_class;
+};
+
+G_DEFINE_TYPE (PangoHbFace, pango_hb_face, PANGO_TYPE_FONT_FACE)
+
+static void
+pango_hb_face_init (PangoHbFace *self)
+{
+}
+
+static void
+pango_hb_face_finalize (GObject *object)
+{
+  PangoHbFace *self = PANGO_HB_FACE (object);
+
+  hb_face_destroy (self->face);
+  pango_font_description_free (self->description);
+  if (self->map)
+    g_object_remove_weak_pointer (G_OBJECT (self->map), (gpointer *)&self->map);
+  g_free (self->name);
+  g_free (self->languages);
+
+  G_OBJECT_CLASS (pango_hb_face_parent_class)->finalize (object);
+}
+
+static const char *
+pango_hb_face_get_face_name (PangoFontFace *face)
+{
+  PangoHbFace *self = PANGO_HB_FACE (face);
+
+  return self->name;
+}
+
+static PangoFontDescription *
+pango_hb_face_describe (PangoFontFace *face)
+{
+  PangoHbFace *self = PANGO_HB_FACE (face);
+
+  return pango_font_description_copy (self->description);
+}
+
+static PangoFontFamily *
+pango_hb_face_get_family (PangoFontFace *face)
+{
+  PangoHbFace *self = PANGO_HB_FACE (face);
+
+  return self->family;
+}
+
+static gboolean
+pango_hb_face_is_synthesized (PangoFontFace *face)
+{
+  PangoHbFace *self = PANGO_HB_FACE (face);
+
+  return self->synthetic;
+}
+
+static void
+pango_hb_face_class_init (PangoHbFaceClass *class)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (class);
+  PangoFontFaceClass *face_class = PANGO_FONT_FACE_CLASS (class);
+
+  object_class->finalize = pango_hb_face_finalize;
+
+  face_class->get_face_name = pango_hb_face_get_face_name;
+  face_class->describe = pango_hb_face_describe;
+  face_class->list_sizes = NULL;
+  face_class->is_synthesized = pango_hb_face_is_synthesized;
+  face_class->get_family = pango_hb_face_get_family;
+}
+
+/* }}} */
+/* {{{ Utilities */
+
+static char *
+strip_family_name (const char *fullname)
+{
+  PangoFontDescription *desc;
+  char *name;
+
+  desc = pango_font_description_from_string (fullname);
+
+  pango_font_description_unset_fields (desc, PANGO_FONT_MASK_FAMILY);
+
+  name = pango_font_description_to_string (desc);
+  if (strcmp (name, "Normal") == 0)
+    {
+      g_free (name);
+      name = g_strdup ("Regular");
+    }
+
+  pango_font_description_free (desc);
+
+  return name;
+}
+
+static char *
+get_name_from_hb_face (hb_face_t       *face,
+                       hb_ot_name_id_t  name_id,
+                       hb_ot_name_id_t  fallback_id)
+{
+  char buf[256];
+  unsigned int len;
+  hb_language_t language;
+
+  language = hb_language_from_string ("en", -1);
+
+  len = sizeof (buf);
+  if (hb_ot_name_get_utf8 (face, name_id, language, &len, buf) > 0)
+    return g_strdup (buf);
+
+  if (fallback_id != HB_OT_NAME_ID_INVALID)
+    {
+      len = sizeof (buf);
+      if (hb_ot_name_get_utf8 (face, fallback_id, language, &len, buf) > 0)
+        return g_strdup (buf);
+    }
+
+  return NULL;
+}
+
+static PangoHbFace *
+pango_hb_face_new_from_blob (hb_blob_t    *blob,
+                             unsigned int  index)
+{
+  PangoHbFace *self;
+  char *family_name;
+  char *fullname;
+
+  self = g_object_new (PANGO_TYPE_HB_FACE, NULL);
+
+  self->face = hb_face_create (blob, index);
+
+  family_name = get_name_from_hb_face (self->face,
+                                       HB_OT_NAME_ID_TYPOGRAPHIC_FAMILY,
+                                       HB_OT_NAME_ID_FONT_FAMILY);
+
+  self->name = get_name_from_hb_face (self->face,
+                                      HB_OT_NAME_ID_TYPOGRAPHIC_SUBFAMILY,
+                                      HB_OT_NAME_ID_FONT_SUBFAMILY);
+
+  fullname = g_strconcat (family_name, " ", self->name, NULL);
+  self->description = pango_font_description_from_string (fullname);
+  g_free (fullname);
+  g_free (family_name);
+
+  self->matrix = (PangoMatrix) PANGO_MATRIX_INIT;
+  self->x_scale = self->y_scale = 1.;
+
+  return self;
+}
+
+/* }}} */
+/* {{{ Private API */
+
+/*< private >
+ * pango_hb_face_set_font_map:
+ * @self: a `PangoHbFace`
+ * @map: a `PangoFontMap`
+ *
+ * Sets the font map of a `PangoHbFace`.
+ *
+ * This should only be called by fontmap implementations.
+ */
+void
+pango_hb_face_set_font_map (PangoHbFace  *self,
+                            PangoFontMap *map)
+{
+  self->map = map;
+  g_object_add_weak_pointer (G_OBJECT (map), (gpointer *)&self->map);
+}
+
+/*< private >
+ * pango_hb_face_set_family:
+ * @self: a `PangoHbFace`
+ * @family: a `PangoFontFamily`
+ *
+ * Sets the font family of a `PangoHbFace`.
+ *
+ * This should only be called by fontmap implementations.
+ */
+void
+pango_hb_face_set_family (PangoHbFace     *self,
+                          PangoFontFamily *family)
+{
+  g_return_if_fail (self->family == NULL);
+  self->family = family;
+}
+
+typedef struct {
+  guint16 major;
+  guint16 minor;
+  gint32 italicAngle;
+  gint16 underlinePosition;
+  gint16 underlineThickness;
+  guint8 isFixedPitch[4];
+} PostTable;
+
+/*< private >
+ * pango_hb_face_is_monospace:
+ * @face: a `PangoHbFace`
+ *
+ * Returns whether @face should be considered monospace.
+ *
+ * Returns: `TRUE` if @face is monospace
+ */
+gboolean
+pango_hb_face_is_monospace (PangoHbFace *face)
+{
+  hb_blob_t *post_blob;
+  guint8 *raw_post;
+  unsigned int post_len;
+  gboolean res = FALSE;
+
+  post_blob = hb_face_reference_table (face->face, HB_TAG ('p', 'o', 's', 't'));
+  raw_post = (guint8 *) hb_blob_get_data (post_blob, &post_len);
+
+  if (post_len >= sizeof (PostTable))
+    {
+      PostTable *post = (PostTable *)raw_post;
+
+      res = post->isFixedPitch[0] != 0 ||
+            post->isFixedPitch[1] != 0 ||
+            post->isFixedPitch[2] != 0 ||
+            post->isFixedPitch[3] != 0;
+    }
+
+  hb_blob_destroy (post_blob);
+
+  return res;
+}
+
+/*< private >
+ * pango_hb_face_is_variable:
+ * @face: a `PangoHbFace`
+ *
+ * Returns whether @face should be considered a variable font.
+ *
+ * Returns: `TRUE` if @face is variable
+ */
+gboolean
+pango_hb_face_is_variable (PangoHbFace *face)
+{
+  return hb_ot_var_get_axis_count (face->face) > 0;
+}
+
+/*< private >
+ * pango_hb_face_get_languages:
+ * @face: a `PangoHbFace`
+ *
+ * Returns the languages supported by @face.
+ *
+ * Returns: (transfer one) (nullable): a NULL-terminated
+ *   array of `PangoLanguage *`
+ */
+PangoLanguage **
+pango_hb_face_get_languages (PangoHbFace *face)
+{
+  return face->languages;
+}
+
+/*< private >
+ * pango_hb_face_set_languages:
+ * @face: a `PangoHbFace`
+ * @languages: (array length=n_languages): the languages supported by @face
+ * @n_languages: the number of languages
+ *
+ * Sets the languages that are supported by @face.
+ *
+ * This should only be called by fontmap implementations.
+ */
+void
+pango_hb_face_set_languages (PangoHbFace          *face,
+                             const PangoLanguage **languages,
+                             gsize                 n_languages)
+{
+  // It would be nicer if HB_OT_META_TAG_SUPPORTED_LANGUAGES was useful
+  g_free (face->languages);
+  face->languages = g_new (PangoLanguage *, n_languages + 1);
+  memcpy (face->languages, languages, n_languages * sizeof (PangoLanguage *));
+  face->languages[n_languages] = NULL;
+}
+
+ /* }}} */
+/* {{{ Public API */
+
+/**
+ * pango_hb_face_new_from_bytes:
+ * @bytes: a `GBytes` containing font data
+ * @index: face index
+ *
+ * Creates a new `PangoHbFace` from font data in memory.
+ *
+ * Returns: a newly created `PangoHbFace`
+ */
+PangoHbFace *
+pango_hb_face_new_from_bytes (GBytes       *bytes,
+                              unsigned int  index)
+{
+  hb_blob_t *blob;
+  PangoHbFace *face;
+
+  blob = hb_blob_create (g_bytes_get_data (bytes, NULL),
+                         g_bytes_get_size (bytes),
+                         HB_MEMORY_MODE_READONLY,
+                         g_bytes_ref (bytes),
+                         (hb_destroy_func_t) g_bytes_unref);
+
+  face = pango_hb_face_new_from_blob (blob, index);
+
+  hb_blob_destroy (blob);
+
+  return face;
+}
+
+/**
+ * pango_hb_face_new_from_file:
+ * @file: font filename
+ * @index: face index
+ *
+ * Creates a new `PangoHbFace` from a font file.
+ *
+ * Returns: a newly created `PangoHbFace`
+ */
+PangoHbFace *
+pango_hb_face_new_from_file (const char   *file,
+                             unsigned int  index)
+{
+  hb_blob_t *blob;
+  PangoHbFace *face;
+
+  blob = hb_blob_create_from_file (file);
+
+  face = pango_hb_face_new_from_blob (blob, index);
+
+  hb_blob_destroy (blob);
+
+  return face;
+}
+
+/**
+ * pango_hb_face_new_transformed:
+ * @face: a `PangoHbFace`
+ * @name: the name for the transformed face
+ * @transform: the transform to apply
+ *
+ * Creates a new `PangoHbFace` that applies the
+ * given @transform to the glyphs in @face.
+ *
+ * Note that the @name should not include the family
+ * name. For example, when using this to create a
+ * synthetic Italic, the name should just be "Italic".
+ *
+ * Returns: (transfer full): a newly created `PangoHbFace`
+ */
+PangoHbFace *
+pango_hb_face_new_transformed (PangoHbFace       *face,
+                               const char        *name,
+                               const PangoMatrix *transform)
+{
+  PangoHbFace *self;
+  const char *family_name;
+  char *fullname;
+
+  g_return_val_if_fail (PANGO_IS_HB_FACE (face), NULL);
+  g_return_val_if_fail (name && *name, NULL);
+  g_return_val_if_fail (transform != NULL, NULL);
+
+  self = g_object_new (PANGO_TYPE_HB_FACE, NULL);
+
+  self->face = hb_face_reference (face->face);
+
+  family_name = pango_font_description_get_family (face->description);
+  self->name = g_strdup (name);
+
+  fullname = g_strconcat (family_name, " ", self->name, NULL);
+  self->description = pango_font_description_from_string (fullname);
+  g_free (fullname);
+
+  self->matrix = *transform;
+  pango_matrix_get_font_scale_factors (&self->matrix, &self->x_scale, &self->y_scale);
+  pango_matrix_scale (&self->matrix, 1./self->x_scale, 1./self->y_scale);
+
+  self->synthetic = TRUE;
+
+  return self;
+}
+
+/**
+ * pango_hb_face_new_alias:
+ * @face: a `PangoHbFace`
+ * @fullname: the full name of the new face
+ *
+ * Creates a new `PangoHbFace that acts as an alias
+ * for the given @face.
+ *
+ * Note that @fullname should include the family name.
+ * For example, when using this to create a monospace
+ * italic font, @fullname should be "Monospace Italic".
+ *
+ * Returns: (transfer full): a newly created `PangoHbFace`
+ */
+PangoHbFace *
+pango_hb_face_new_alias (PangoHbFace *face,
+                         const char  *fullname)
+{
+  PangoHbFace *self;
+
+  g_return_val_if_fail (PANGO_IS_HB_FACE (face), NULL);
+  g_return_val_if_fail (fullname && *fullname, NULL);
+
+  self = g_object_new (PANGO_TYPE_HB_FACE, NULL);
+
+  self->face = hb_face_reference (face->face);
+
+  self->name = strip_family_name (fullname);
+  self->description = pango_font_description_from_string (fullname);
+
+  self->matrix = (PangoMatrix) PANGO_MATRIX_INIT;
+  self->x_scale = self->y_scale = 1.;
+
+  self->synthetic = TRUE;
+
+  return self;
+}
+
+/* }}} */
+
+/* vim:set foldmethod=marker expandtab: */
diff --git a/pango/pango-hbface.h b/pango/pango-hbface.h
new file mode 100644
index 00000000..dc06ca30
--- /dev/null
+++ b/pango/pango-hbface.h
@@ -0,0 +1,50 @@
+/* Pango
+ *
+ * Copyright (C) 2021 Matthias Clasen
+ *
+ * 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-font.h>
+
+#include <hb.h>
+
+G_BEGIN_DECLS
+
+#define PANGO_TYPE_HB_FACE      (pango_hb_face_get_type ())
+PANGO_AVAILABLE_IN_1_50
+G_DECLARE_FINAL_TYPE (PangoHbFace, pango_hb_face, PANGO, HB_FACE, PangoFontFace)
+
+PANGO_AVAILABLE_IN_1_50
+PangoHbFace *   pango_hb_face_new_from_file     (const char             *file,
+                                                 unsigned int            index);
+
+PANGO_AVAILABLE_IN_1_50
+PangoHbFace *   pango_hb_face_new_from_bytes    (GBytes                 *bytes,
+                                                 unsigned int            index);
+
+PANGO_AVAILABLE_IN_1_50
+PangoHbFace *   pango_hb_face_new_transformed   (PangoHbFace            *face,
+                                                 const char             *name,
+                                                 const PangoMatrix      *transform);
+
+PANGO_AVAILABLE_IN_1_50
+PangoHbFace *   pango_hb_face_new_alias         (PangoHbFace            *face,
+                                                 const char             *fullname);
+
+G_END_DECLS
diff --git a/pango/pango.h b/pango/pango.h
index 8dc86b13..019c12c9 100644
--- a/pango/pango.h
+++ b/pango/pango.h
@@ -38,6 +38,7 @@
 #include <pango/pango-glyph.h>
 #include <pango/pango-glyph-item.h>
 #include <pango/pango-gravity.h>
+#include <pango/pango-hbface.h>
 #include <pango/pango-item.h>
 #include <pango/pango-language.h>
 #include <pango/pango-layout.h>