[pango/simple-fontmap: 1/6] Add PangoHbFont and PangoSimpleFontMap

[Matthias Clasen <matthiasc src gnome org>]

commit 171f52897114c63bbd690dbe25384a5a439a4452
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Aug 27 22:08:14 2021 -0400

    Add PangoHbFont and PangoSimpleFontMap
    
    This is an attempt to make a font backend that does
    not depend on platform specifics and can be used in
    tests.
    
    We add PangoHbFont and PangoHbFace to wrap hb_font_t
    and hb_face_t, and a very basic fontmap implementation.

 pango/meson.build            |   3 +
 pango/pango-hbface-private.h |  23 +++
 pango/pango-hbface.c         | 143 +++++++++++++++
 pango/pango-hbface.h         |  36 ++++
 pango/pango-hbfont-private.h |  15 ++
 pango/pango-hbfont.c         | 416 +++++++++++++++++++++++++++++++++++++++++++
 pango/pango-hbfont.h         |  41 +++++
 pango/pango-simplefontmap.c  | 332 ++++++++++++++++++++++++++++++++++
 pango/pango-simplefontmap.h  |  46 +++++
 pango/pango.h                |   1 +
 10 files changed, 1056 insertions(+)
---
diff --git a/pango/meson.build b/pango/meson.build
index 084de229..482372cb 100644
--- a/pango/meson.build
+++ b/pango/meson.build
@@ -27,6 +27,9 @@ pango_sources = [
   'pango-utils.c',
   'reorder-items.c',
   'shape.c',
+  'pango-hbfont.c',
+  'pango-hbface.c',
+  'pango-simplefontmap.c',
 ]
 
 pango_headers = [
diff --git a/pango/pango-hbface-private.h b/pango/pango-hbface-private.h
new file mode 100644
index 00000000..e6f378cc
--- /dev/null
+++ b/pango/pango-hbface-private.h
@@ -0,0 +1,23 @@
+#pragma once
+
+#include "pango-hbface.h"
+#include "pango-fontmap.h"
+#include <hb.h>
+
+struct _PangoHbFace
+{
+  PangoFontFace parent_instance;
+
+  hb_blob_t *blob;
+  unsigned int index;
+  hb_face_t *face;
+  PangoFontDescription *description;
+  char *name;
+  const char *family;
+
+  PangoFontMap *map;
+};
+
+void
+pango_hb_face_set_font_map (PangoHbFace  *self,
+                            PangoFontMap *map);
diff --git a/pango/pango-hbface.c b/pango/pango-hbface.c
new file mode 100644
index 00000000..5f9306b1
--- /dev/null
+++ b/pango/pango-hbface.c
@@ -0,0 +1,143 @@
+/* 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>
+
+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_blob_destroy (self->blob);
+  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_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);
+
+  if (self->map)
+    return pango_font_map_get_family (self->map, self->family);
+
+  return NULL;
+}
+
+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 = NULL;
+  face_class->get_family = pango_hb_face_get_family;
+}
+
+static char *
+get_name_from_hb_face (hb_face_t       *face,
+                       hb_ot_name_id_t  name_id)
+{
+  char buf[256];
+  unsigned int len = sizeof (buf);
+  hb_language_t language;
+
+  language = hb_language_from_string ("en", -1);
+
+  hb_ot_name_get_utf8 (face, name_id, language, &len, buf);
+
+  return g_strdup (buf);
+}
+
+PangoHbFace *
+pango_hb_face_new (const char   *file,
+                   unsigned int  index)
+{
+  PangoHbFace *self;
+  char *name;
+
+  self = g_object_new (PANGO_TYPE_HB_FACE, NULL);
+
+  self->blob = hb_blob_create_from_file (file);
+  self->index = index;
+  self->face = hb_face_create (self->blob, index);
+
+  name = get_name_from_hb_face (self->face, HB_OT_NAME_ID_FULL_NAME);
+  self->description = pango_font_description_from_string (name);
+  g_free (name);
+
+  self->family = pango_font_description_get_family (self->description);
+
+  self->name = get_name_from_hb_face (self->face, HB_OT_NAME_ID_TYPOGRAPHIC_SUBFAMILY);
+  if (!self->name)
+    self->name = get_name_from_hb_face (self->face, HB_OT_NAME_ID_FONT_SUBFAMILY);
+
+  return self;
+}
+
+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);
+}
diff --git a/pango/pango-hbface.h b/pango/pango-hbface.h
new file mode 100644
index 00000000..96efb6a2
--- /dev/null
+++ b/pango/pango-hbface.h
@@ -0,0 +1,36 @@
+/* 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 ())
+G_DECLARE_FINAL_TYPE (PangoHbFace, pango_hb_face, PANGO, HB_FACE, PangoFontFace)
+
+PANGO_AVAILABLE_IN_1_50
+PangoHbFace *pango_hb_face_new (const char   *file,
+                                unsigned int  index);
+
+G_END_DECLS
diff --git a/pango/pango-hbfont-private.h b/pango/pango-hbfont-private.h
new file mode 100644
index 00000000..3e1c98d1
--- /dev/null
+++ b/pango/pango-hbfont-private.h
@@ -0,0 +1,15 @@
+#pragma once
+
+#include "pango-hbfont.h"
+#include "pango-hbface.h"
+#include <hb.h>
+
+struct _PangoHbFont
+{
+  PangoFont parent_instance;
+
+  PangoHbFace *face;
+  PangoFontDescription *description;
+  PangoGravity gravity;
+  double dpi;
+};
diff --git a/pango/pango-hbfont.c b/pango/pango-hbfont.c
new file mode 100644
index 00000000..74895845
--- /dev/null
+++ b/pango/pango-hbfont.c
@@ -0,0 +1,416 @@
+/* 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-hbfont-private.h"
+
+#include "pango-font-private.h"
+#include "pango-coverage-private.h"
+#include "pango-hbface-private.h"
+#include "pango-impl-utils.h"
+
+#include <hb-ot.h>
+
+struct _PangoHbFontClass
+{
+  PangoFontClass parent_class;
+};
+
+G_DEFINE_TYPE (PangoHbFont, pango_hb_font, PANGO_TYPE_FONT)
+
+static void
+pango_hb_font_init (PangoHbFont *self)
+{
+  self->gravity = PANGO_GRAVITY_SOUTH;
+  self->dpi = 96.;
+}
+
+static void
+pango_hb_font_finalize (GObject *object)
+{
+  PangoHbFont *self = PANGO_HB_FONT (object);
+
+  g_object_unref (self->face);
+  pango_font_description_free (self->description);
+
+  G_OBJECT_CLASS (pango_hb_font_parent_class)->finalize (object);
+}
+
+static PangoFontDescription *
+pango_hb_font_describe (PangoFont *font)
+{
+  PangoHbFont *self = PANGO_HB_FONT (font);
+
+  return pango_font_description_copy (self->description);
+}
+
+/* {{{ PangoHbCoverage */
+
+typedef struct
+{
+  PangoCoverage parent_instance;
+  hb_font_t *hb_font;
+} PangoHbCoverage;
+
+typedef struct
+{
+  PangoCoverageClass parent_class;
+} PangoHbCoverageClass;
+
+GType pango_hb_coverage_get_type (void) G_GNUC_CONST;
+
+G_DEFINE_TYPE (PangoHbCoverage, pango_hb_coverage, PANGO_TYPE_COVERAGE)
+
+static void
+pango_hb_coverage_init (PangoHbCoverage *self)
+{
+}
+
+static PangoCoverageLevel
+pango_hb_coverage_get (PangoCoverage *coverage,
+                       int            index)
+{
+  PangoHbCoverage *self = (PangoHbCoverage*)coverage;
+  hb_codepoint_t glyph;
+
+  return hb_font_get_nominal_glyph (self->hb_font, index, &glyph)
+         ? PANGO_COVERAGE_EXACT
+         : PANGO_COVERAGE_NONE;
+}
+
+static void
+pango_hb_coverage_set (PangoCoverage      *coverage,
+                       int                 index,
+                       PangoCoverageLevel  level)
+{
+}
+
+static PangoCoverage *
+pango_hb_coverage_copy (PangoCoverage *coverage)
+{
+  PangoHbCoverage *self = (PangoHbCoverage*)coverage;
+  PangoHbCoverage *copy;
+
+  copy = g_object_new (pango_hb_coverage_get_type (), NULL);
+  copy->hb_font = hb_font_reference (self->hb_font);
+
+  return (PangoCoverage *)copy;
+}
+
+static void
+pango_hb_coverage_finalize (GObject *object)
+{
+  PangoHbCoverage *self = (PangoHbCoverage*)object;
+
+  hb_font_destroy (self->hb_font);
+
+  G_OBJECT_CLASS (pango_hb_coverage_parent_class)->finalize (object);
+}
+
+static void
+pango_hb_coverage_class_init (PangoHbCoverageClass *class)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (class);
+  PangoCoverageClass *coverage_class = PANGO_COVERAGE_CLASS (class);
+
+  object_class->finalize = pango_hb_coverage_finalize;
+
+  coverage_class->get = pango_hb_coverage_get;
+  coverage_class->set = pango_hb_coverage_set;
+  coverage_class->copy = pango_hb_coverage_copy;
+}
+
+/* }}} */
+
+static PangoCoverage *
+pango_hb_font_get_coverage (PangoFont     *font,
+                            PangoLanguage *language G_GNUC_UNUSED)
+{
+  hb_font_t *hb_font = pango_font_get_hb_font (font);
+  PangoHbCoverage *coverage;
+
+  coverage = g_object_new (pango_hb_coverage_get_type (), NULL);
+  coverage->hb_font = hb_font_reference (hb_font);
+
+  return (PangoCoverage *)coverage;
+}
+
+static int
+get_average_char_width (hb_font_t  *font,
+                        const char *text)
+{
+  int width = 0;
+
+  for (const char *p = text; *p; p = g_utf8_next_char (p))
+    {
+      gunichar wc;
+      hb_codepoint_t glyph;
+      hb_glyph_extents_t extents;
+
+      wc = g_utf8_get_char (p);
+      if (hb_font_get_nominal_glyph (font, wc, &glyph) &&
+          hb_font_get_glyph_extents (font, glyph, &extents))
+        {
+          width += extents.x_bearing + extents.width;
+        }
+    }
+
+  return width / pango_utf8_strwidth (text);
+}
+
+static int
+get_max_char_width (hb_font_t  *font,
+                    const char *text)
+{
+  int width = 0;
+
+  for (const char *p = text; *p; p = g_utf8_next_char (p))
+    {
+      gunichar wc;
+      hb_codepoint_t glyph;
+      hb_glyph_extents_t extents;
+
+      wc = g_utf8_get_char (p);
+      if (hb_font_get_nominal_glyph (font, wc, &glyph) &&
+          hb_font_get_glyph_extents (font, glyph, &extents))
+        {
+          width = MAX (width, extents.x_bearing + extents.width);
+        }
+    }
+
+  return width;
+}
+
+static void
+pango_hb_font_get_glyph_extents (PangoFont      *font,
+                                 PangoGlyph      glyph,
+                                 PangoRectangle *ink_rect,
+                                 PangoRectangle *logical_rect)
+{
+  hb_font_t *hb_font = pango_font_get_hb_font (font);
+  hb_glyph_extents_t extents;
+
+  /* FIXME handle unknown glyphs and visible ignorables */
+  hb_font_get_glyph_extents (hb_font, glyph, &extents);
+
+  if (ink_rect)
+    {
+      ink_rect->x = extents.x_bearing;
+      ink_rect->width = extents.width;
+      ink_rect->y = - extents.y_bearing;
+      ink_rect->height = - extents.height;
+    }
+
+  if (logical_rect)
+    {
+      hb_font_extents_t font_extents;
+      hb_position_t x, y;
+      hb_direction_t direction;
+
+      direction = PANGO_GRAVITY_IS_VERTICAL (PANGO_HB_FONT (font)->gravity)
+                  ? HB_DIRECTION_TTB : HB_DIRECTION_LTR;
+
+      hb_font_get_extents_for_direction (hb_font, direction, &font_extents);
+      hb_font_get_glyph_advance_for_direction (hb_font, glyph, direction, &x, &y);
+
+      logical_rect->x = 0;
+      logical_rect->width = x;
+      logical_rect->y = - font_extents.ascender;
+      logical_rect->height = font_extents.ascender - font_extents.descender;
+    }
+}
+
+static PangoFontMetrics *
+pango_hb_font_get_metrics (PangoFont     *font,
+                           PangoLanguage *language)
+{
+  hb_font_t *hb_font = pango_font_get_hb_font (font);
+  PangoFontMetrics *metrics;
+  hb_font_extents_t extents;
+  hb_position_t position;
+
+  metrics = pango_font_metrics_new ();
+
+  hb_font_get_extents_for_direction (hb_font, HB_DIRECTION_LTR, &extents);
+
+  metrics->descent = - extents.descender;
+  metrics->ascent = extents.ascender;
+  metrics->height = extents.ascender - extents.descender + extents.line_gap;
+
+  metrics->underline_thickness = PANGO_SCALE;
+  metrics->underline_position = - PANGO_SCALE;
+  metrics->strikethrough_thickness = PANGO_SCALE;
+  metrics->strikethrough_position = metrics->ascent / 2;
+
+  if (hb_ot_metrics_get_position (hb_font, HB_OT_METRICS_TAG_UNDERLINE_SIZE, &position))
+    metrics->underline_thickness = position;
+
+  if (hb_ot_metrics_get_position (hb_font, HB_OT_METRICS_TAG_UNDERLINE_OFFSET, &position))
+    metrics->underline_position = position;
+
+  if (hb_ot_metrics_get_position (hb_font, HB_OT_METRICS_TAG_STRIKEOUT_SIZE, &position))
+    metrics->strikethrough_thickness = position;
+
+  if (hb_ot_metrics_get_position (hb_font, HB_OT_METRICS_TAG_STRIKEOUT_OFFSET, &position))
+    metrics->strikethrough_position = position;
+
+  metrics->approximate_char_width = get_average_char_width (hb_font, pango_language_get_sample_string 
(language));
+  metrics->approximate_digit_width = get_max_char_width (hb_font, "0123456789");
+
+  return metrics;
+}
+
+static void
+parse_variations (const char            *variations,
+                  hb_ot_var_axis_info_t *axes,
+                  int                    n_axes,
+                  float                 *coords)
+{
+  const char *p;
+  const char *end;
+  hb_variation_t var;
+  int i;
+
+  p = variations;
+  while (p && *p)
+    {
+      end = strchr (p, ',');
+      if (hb_variation_from_string (p, end ? end - p: -1, &var))
+        {
+          for (i = 0; i < n_axes; i++)
+            {
+              if (axes[i].tag == var.tag)
+                {
+                  coords[axes[i].axis_index] = var.value;
+                  break;
+                }
+            }
+        }
+
+      p = end ? end + 1 : NULL;
+    }
+}
+
+static hb_font_t *
+pango_hb_font_create_hb_font (PangoFont *font)
+{
+  PangoHbFont *self = PANGO_HB_FONT (font);
+  hb_face_t *hb_face = self->face->face;
+  hb_font_t *hb_font;
+  int size;
+  unsigned int n_axes;
+  hb_ot_var_axis_info_t axes[32];
+  float coords[32];
+  const char *variations;
+
+  hb_font = hb_font_create (hb_face);
+
+  // TODO Matrix ?
+
+  /* Size */
+  size = pango_font_description_get_size (self->description);
+  hb_font_set_scale (hb_font,
+                     size * (self->dpi / 72.),
+                     size * (self->dpi / 72.));
+
+  /* Variations */
+  n_axes = G_N_ELEMENTS (axes);
+  hb_ot_var_get_axis_infos (hb_face, 0, &n_axes, axes);
+  if (n_axes > 0)
+    {
+      for (int i = 0; i < n_axes; i++)
+        coords[axes[i].axis_index] = axes[i].default_value;
+
+      variations = pango_font_description_get_variations (self->description);
+      parse_variations (variations, axes, n_axes, coords);
+
+      hb_font_set_var_coords_design (hb_font, coords, n_axes);
+    }
+
+  return hb_font;
+}
+
+static PangoLanguage **
+pango_hb_font_get_languages (PangoFont *font)
+{
+  // TODO Use HB_OT_META_TAG_SUPPORTED_LANGUAGES
+  return NULL;
+}
+
+static gboolean
+pango_hb_font_has_char (PangoFont *font,
+                        gunichar   wc)
+{
+  hb_font_t *hb_font = pango_font_get_hb_font (font);
+  hb_codepoint_t glyph;
+
+  return hb_font_get_nominal_glyph (hb_font, wc, &glyph);
+}
+
+static PangoFontFace *
+pango_hb_font_get_face (PangoFont *font)
+{
+  PangoHbFont *self = PANGO_HB_FONT (font);
+
+  return PANGO_FONT_FACE (self->face);
+}
+
+static void
+pango_hb_font_class_init (PangoHbFontClass *class)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (class);
+  PangoFontClass *font_class = PANGO_FONT_CLASS (class);
+  PangoFontClassPrivate *pclass;
+
+  object_class->finalize = pango_hb_font_finalize;
+
+  font_class->describe = pango_hb_font_describe;
+  font_class->get_coverage = pango_hb_font_get_coverage;
+  font_class->get_glyph_extents = pango_hb_font_get_glyph_extents;
+  font_class->get_metrics = pango_hb_font_get_metrics;
+  font_class->create_hb_font = pango_hb_font_create_hb_font;
+
+  pclass = g_type_class_get_private ((GTypeClass *) class, PANGO_TYPE_FONT);
+
+  pclass->get_languages = pango_hb_font_get_languages;
+  pclass->has_char = pango_hb_font_has_char;
+  pclass->get_face = pango_hb_font_get_face;
+}
+
+PangoHbFont *
+pango_hb_font_new (PangoHbFace                *face,
+                   const PangoFontDescription *description,
+                   PangoGravity                gravity,
+                   double                      dpi)
+{
+  PangoHbFont *font;
+
+  font = g_object_new (PANGO_TYPE_HB_FONT, NULL);
+
+  font->face = g_object_ref (face);
+  font->description = pango_font_description_copy (description);
+  font->gravity = gravity;
+  font->dpi = dpi;
+
+  return font;
+}
+
+/* vim:set foldmethod=marker expandtab: */
diff --git a/pango/pango-hbfont.h b/pango/pango-hbfont.h
new file mode 100644
index 00000000..3d388701
--- /dev/null
+++ b/pango/pango-hbfont.h
@@ -0,0 +1,41 @@
+/* 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 <pango/pango-hbface.h>
+
+#include <hb.h>
+
+G_BEGIN_DECLS
+
+#define PANGO_TYPE_HB_FONT      (pango_hb_font_get_type ())
+
+PANGO_AVAILABLE_IN_1_50
+G_DECLARE_FINAL_TYPE (PangoHbFont, pango_hb_font, PANGO, HB_FONT, PangoFont)
+
+PANGO_AVAILABLE_IN_1_50
+PangoHbFont *           pango_hb_font_new               (PangoHbFace                 *face,
+                                                         const PangoFontDescription  *description,
+                                                         PangoGravity                 gravity,
+                                                         double                       dpi);
+
+G_END_DECLS
diff --git a/pango/pango-simplefontmap.c b/pango/pango-simplefontmap.c
new file mode 100644
index 00000000..4dc0a885
--- /dev/null
+++ b/pango/pango-simplefontmap.c
@@ -0,0 +1,332 @@
+/* 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 "pango-simplefontmap.h"
+#include "pango-hbface-private.h"
+#include "pango-hbfont-private.h"
+#include "pango-context.h"
+#include "pango-impl-utils.h"
+
+struct _PangoSimpleFontMap
+{
+  PangoFontMap parent_instance;
+
+  GPtrArray *families;
+  GPtrArray *faces;
+
+  double dpi;
+};
+
+struct _PangoSimpleFontMapClass
+{
+  PangoFontMapClass parent_class;
+};
+
+G_DEFINE_TYPE (PangoSimpleFontMap, pango_simple_font_map, PANGO_TYPE_FONT_MAP)
+
+static void
+pango_simple_font_map_init (PangoSimpleFontMap *self)
+{
+  self->families = g_ptr_array_new_with_free_func (g_object_unref);
+  self->faces = g_ptr_array_new_with_free_func (g_object_unref);
+
+  self->dpi = 96.;
+}
+
+static void
+pango_simple_font_map_finalize (GObject *object)
+{
+  PangoSimpleFontMap *self = PANGO_SIMPLE_FONT_MAP (object);
+
+  g_ptr_array_free (self->families, TRUE);
+  g_ptr_array_free (self->faces, TRUE);
+
+  G_OBJECT_CLASS (pango_simple_font_map_parent_class)->finalize (object);
+}
+
+/* {{{ PangoSimpleFamily */
+
+#define PANGO_TYPE_SIMPLE_FAMILY      (pango_simple_family_get_type ())
+G_DECLARE_FINAL_TYPE (PangoSimpleFamily, pango_simple_family, PANGO, SIMPLE_FAMILY, PangoFontFamily)
+
+struct _PangoSimpleFamily
+{
+  PangoFontFamily parent_instance;
+
+  PangoSimpleFontMap *map;
+  char *name;
+};
+
+struct _PangoSimpleFamilyClass
+{
+  PangoFontFamilyClass parent_class;
+};
+
+G_DEFINE_TYPE (PangoSimpleFamily, pango_simple_family, PANGO_TYPE_FONT_FAMILY)
+
+static void
+pango_simple_family_init (PangoSimpleFamily *self)
+{
+}
+
+static void
+pango_simple_family_finalize (GObject *object)
+{
+  PangoSimpleFamily *self = PANGO_SIMPLE_FAMILY (object);
+
+  g_free (self->name);
+  if (self->map)
+    g_object_remove_weak_pointer (G_OBJECT (self->map), (gpointer *)&self->map);
+
+  G_OBJECT_CLASS (pango_simple_family_parent_class)->finalize (object);
+}
+
+static const char *
+pango_simple_family_get_name (PangoFontFamily *family)
+{
+  PangoSimpleFamily *self = PANGO_SIMPLE_FAMILY (family);
+
+  return self->name;
+}
+
+static void
+pango_simple_family_list_faces (PangoFontFamily  *family,
+                                PangoFontFace  ***faces,
+                                int              *n_faces)
+{
+  PangoSimpleFamily *self = PANGO_SIMPLE_FAMILY (family);
+  GPtrArray *result;
+
+  if (!self->map)
+    {
+      if (faces)
+        *faces = NULL;
+      if (n_faces)
+        *n_faces = 0;
+      return;
+    }
+
+  result = g_ptr_array_new ();
+  for (int i = 0; i < self->map->faces->len; i++)
+    {
+      PangoHbFace *face = g_ptr_array_index (self->map->faces, i);
+
+      if (strcmp (self->name, face->family) == 0)
+        g_ptr_array_add (result, face);
+    }
+
+  if (n_faces)
+    *n_faces = result->len;
+
+  if (faces)
+    *faces = (PangoFontFace **) g_ptr_array_free (result, FALSE);
+}
+
+static PangoFontFace *
+pango_simple_family_get_face (PangoFontFamily *family,
+                               const char      *name)
+{
+  PangoSimpleFamily *self = PANGO_SIMPLE_FAMILY (family);
+
+  if (!self->map)
+    return NULL;
+
+  for (int i = 0; i < self->map->faces->len; i++)
+    {
+      PangoHbFace *face = g_ptr_array_index (self->map->faces, i);
+
+      if (strcmp (self->name, face->family) == 0 &&
+          strcmp (name, face->name) == 0)
+        return PANGO_FONT_FACE (face);
+    }
+
+  return NULL;
+}
+
+static void
+pango_simple_family_class_init (PangoSimpleFamilyClass *class)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (class);
+  PangoFontFamilyClass *family_class = PANGO_FONT_FAMILY_CLASS (class);
+
+  object_class->finalize = pango_simple_family_finalize;
+
+  family_class->list_faces = pango_simple_family_list_faces;
+  family_class->get_name = pango_simple_family_get_name;
+  family_class->is_monospace = NULL;
+  family_class->is_variable = NULL;
+  family_class->get_face = pango_simple_family_get_face;
+}
+
+static PangoSimpleFamily *
+pango_simple_family_new (const char         *name,
+                         PangoSimpleFontMap *map)
+{
+  PangoSimpleFamily *self;
+
+  self = g_object_new (PANGO_TYPE_SIMPLE_FAMILY, NULL);
+
+  self->name = g_strdup (name);
+  self->map = map;
+  g_object_add_weak_pointer (G_OBJECT (map), (gpointer *)&self->map);
+
+  return self;
+}
+
+/* }}} */
+
+static PangoFont *
+pango_simple_font_map_load_font (PangoFontMap               *map,
+                                 PangoContext               *context,
+                                 const PangoFontDescription *desc)
+{
+  PangoSimpleFontMap *self = PANGO_SIMPLE_FONT_MAP (map);
+  PangoFontDescription *best = NULL;
+  PangoHbFace *face = NULL;
+  PangoHbFont *font;
+
+  for (int i = 0; i < self->faces->len; i++)
+    {
+      PangoHbFace *face2 = g_ptr_array_index (self->faces, i);
+
+      if (pango_font_description_better_match (desc, best, face2->description))
+        {
+          face = face2;
+          best = face2->description;
+        }
+    }
+  if (face == NULL)
+    face = g_ptr_array_index (self->faces, 0);
+
+  font = pango_hb_font_new (face, desc, pango_context_get_gravity (context), self->dpi);
+
+  return PANGO_FONT (font);
+}
+
+static PangoFontset *
+pango_simple_font_map_load_fontset (PangoFontMap               *map,
+                                    PangoContext               *context,
+                                    const PangoFontDescription *description,
+                                    PangoLanguage              *language)
+{
+  PangoFontsetSimple *fontset;
+
+  // TODO: Do the FcFontSort thing
+  fontset = pango_fontset_simple_new (language);
+  pango_fontset_simple_append (fontset, pango_font_map_load_font (map, context, description));
+
+  return PANGO_FONTSET (fontset);
+}
+
+static void
+pango_simple_font_map_list_families (PangoFontMap      *map,
+                                     PangoFontFamily ***families,
+                                     int               *n_families)
+{
+  PangoSimpleFontMap *self = PANGO_SIMPLE_FONT_MAP (map);
+
+  if (self->families->len == 0)
+    {
+      if (families)
+        *families = NULL;
+      if (n_families)
+        *n_families = 0;
+
+      return;
+    }
+
+  if (n_families)
+    *n_families = self->families->len;
+
+  if (families)
+    *families = g_memdup2 (self->families->pdata, self->families->len * sizeof (PangoFontFamily *));
+}
+
+static PangoFontFamily *
+pango_simple_font_map_get_family (PangoFontMap *map,
+                                  const char   *name)
+{
+  PangoSimpleFontMap *self = PANGO_SIMPLE_FONT_MAP (map);
+
+  for (int i = 0; i < self->families->len; i++)
+    {
+      PangoSimpleFamily *family = g_ptr_array_index (self->families, i);
+
+      if (strcmp (name, family->name) == 0)
+        return PANGO_FONT_FAMILY (family);
+    }
+
+  return NULL;
+}
+
+static void
+pango_simple_font_map_class_init (PangoSimpleFontMapClass *class)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (class);
+  PangoFontMapClass *map_class = PANGO_FONT_MAP_CLASS (class);
+
+  object_class->finalize = pango_simple_font_map_finalize;
+
+  map_class->load_font = pango_simple_font_map_load_font;
+  map_class->load_fontset = pango_simple_font_map_load_fontset;
+  map_class->list_families = pango_simple_font_map_list_families;
+  map_class->get_family = pango_simple_font_map_get_family;
+  map_class->get_face = NULL;
+}
+
+PangoSimpleFontMap *
+pango_simple_font_map_new (void)
+{
+  return g_object_new (PANGO_TYPE_SIMPLE_FONT_MAP, NULL);
+}
+
+void
+pango_simple_font_map_add_file (PangoSimpleFontMap *self,
+                                const char         *file,
+                                unsigned int        index)
+{
+  PangoFontMap *map = PANGO_FONT_MAP (self);
+  PangoHbFace *face;
+
+  face = pango_hb_face_new (file, index);
+
+  pango_hb_face_set_font_map (face, map);
+
+  if (!pango_simple_font_map_get_family (map, face->family))
+    g_ptr_array_add (self->families, pango_simple_family_new (face->family, self));
+
+  g_ptr_array_add (self->faces, face);
+}
+
+void
+pango_simple_font_map_set_resolution (PangoSimpleFontMap *self,
+                                      double              dpi)
+{
+  self->dpi = dpi;
+
+  pango_font_map_changed (PANGO_FONT_MAP (self));
+}
+
+/* vim:set foldmethod=marker expandtab: */
diff --git a/pango/pango-simplefontmap.h b/pango/pango-simplefontmap.h
new file mode 100644
index 00000000..9aa67fd3
--- /dev/null
+++ b/pango/pango-simplefontmap.h
@@ -0,0 +1,46 @@
+/* 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-font.h>
+#include <pango-fontmap.h>
+#include <hb.h>
+
+G_BEGIN_DECLS
+
+#define PANGO_TYPE_SIMPLE_FONT_MAP   (pango_simple_font_map_get_type ())
+
+PANGO_AVAILABLE_IN_1_50
+G_DECLARE_FINAL_TYPE (PangoSimpleFontMap, pango_simple_font_map, PANGO, SIMPLE_FONT_MAP, PangoFontMap)
+
+PANGO_AVAILABLE_IN_1_50
+PangoSimpleFontMap *    pango_simple_font_map_new       (void);
+
+PANGO_AVAILABLE_IN_1_50
+void                    pango_simple_font_map_add_file  (PangoSimpleFontMap   *self,
+                                                         const char           *file,
+                                                         unsigned int          index);
+
+PANGO_AVAILABLE_IN_1_50
+void                    pango_simple_font_map_set_resolution (PangoSimpleFontMap *self,
+                                                              double              dpi);
+
+G_END_DECLS
diff --git a/pango/pango.h b/pango/pango.h
index 8dc86b13..cf594e55 100644
--- a/pango/pango.h
+++ b/pango/pango.h
@@ -45,6 +45,7 @@
 #include <pango/pango-markup.h>
 #include <pango/pango-renderer.h>
 #include <pango/pango-script.h>
+#include <pango/pango-simplefontmap.h>
 #include <pango/pango-tabs.h>
 #include <pango/pango-types.h>
 #include <pango/pango-utils.h>