Add layout serialization api

Add api to serialize PangoLayout, for the benefit
of testing and debugging. Currently, this uses
json, but that is an implementation detail.

Some tests included.

6 files changed, 1133 insertions, 3 deletions

diff --git a/meson.build b/meson.build
index 37bcf6cb..4acb0654 100644
--- a/meson.build
+++ b/meson.build
@@ -232,6 +232,7 @@ harfbuzz_req_version = '>= 2.6.0'
 fontconfig_req_version = '>= 2.13.0'
 xft_req_version = '>= 2.0.0'
 cairo_req_version = '>= 1.12.10'
+json_glib_version = '>= 1.6.0'
 
 # libm
 mathlib_dep = cc.find_library('m', required: false)
@@ -251,6 +252,9 @@ fribidi_dep = dependency('fribidi', version: fribidi_req_version,
                          default_options: ['docs=false'])
 pango_deps += fribidi_dep
 
+json_glib_dep = dependency('json-glib-1.0', version: json_glib_version)
+pango_deps += json_glib_dep
+
 thai_dep = dependency('libthai', version: libthai_req_version, required: get_option('libthai'))
 if thai_dep.found()
   pango_conf.set('HAVE_LIBTHAI', 1)
diff --git a/pango/meson.build b/pango/meson.build
index 084de229..7c7bb280 100644
--- a/pango/meson.build
+++ b/pango/meson.build
@@ -27,6 +27,7 @@ pango_sources = [
   'pango-utils.c',
   'reorder-items.c',
   'shape.c',
+  'serializer.c',
 ]
 
 pango_headers = [
diff --git a/pango/pango-attributes.c b/pango/pango-attributes.c
index 13468963..cfaf9b17 100644
--- a/pango/pango-attributes.c
+++ b/pango/pango-attributes.c
@@ -2802,7 +2802,7 @@ pango_attr_list_from_string (const char *text)
 
       p = endp + strspn (endp, " ");
 
-      endp = (char *)strpbrk (p, " ");
+      endp = (char *)p + strcspn (p, " ");
       attr_type = get_attr_type_by_nick (p, endp - p);
 
       p = endp + strspn (endp, " ");
@@ -2929,8 +2929,7 @@ pango_attr_list_from_string (const char *text)
           break;
 
         case PANGO_ATTR_SHAPE:
-          endp = (char *)strpbrk (p, ",\n");
-          p = endp  + strspn (endp, " ");
+          endp = (char *)p + strcspn (p, ",\n");
           continue; /* FIXME */
 
         case PANGO_ATTR_SCALE:
diff --git a/pango/pango-layout.h b/pango/pango-layout.h
index e28f9295..502f5e29 100644
--- a/pango/pango-layout.h
+++ b/pango/pango-layout.h
@@ -351,6 +351,31 @@ GSList *         pango_layout_get_lines            (PangoLayout    *layout);
 PANGO_AVAILABLE_IN_1_16
 GSList *         pango_layout_get_lines_readonly   (PangoLayout    *layout);
 
+#define PANGO_LAYOUT_SERIALIZE_ERROR (pango_layout_serialize_error_quark ())
+
+typedef enum {
+  PANGO_LAYOUT_SERIALIZE_INVALID,
+  PANGO_LAYOUT_SERIALIZE_INVALID_SYNTAX,
+  PANGO_LAYOUT_SERIALIZE_INVALID_VALUE,
+  PANGO_LAYOUT_SERIALIZE_MISSING_VALUE,
+} PangoLayoutSerializeError;
+
+PANGO_AVAILABLE_IN_1_50
+GQuark          pango_layout_serialize_error_quark (void);
+
+PANGO_AVAILABLE_IN_1_50
+GBytes *        pango_layout_serialize             (PangoLayout    *layout);
+
+PANGO_AVAILABLE_IN_1_50
+PangoLayout *   pango_layout_deserialize           (PangoContext   *context,
+                                                    GBytes         *bytes,
+                                                    GError        **error);
+
+PANGO_AVAILABLE_IN_1_50
+gboolean        pango_layout_write_to_file          (PangoLayout   *layout,
+                                                     const char    *filename,
+                                                     GError       **error);
+
 
 #define PANGO_TYPE_LAYOUT_LINE (pango_layout_line_get_type ())
 
diff --git a/pango/serializer.c b/pango/serializer.c
new file mode 100644
index 00000000..576e6cf6
--- /dev/null
+++ b/pango/serializer.c
@@ -0,0 +1,935 @@
+/* Pango
+ * serializer.c: Code to serialize various Pango objects
+ *
+ * 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 <pango/pango-layout.h>
+#include <pango/pango-layout-private.h>
+#include <pango/pango-enum-types.h>
+
+#include <json-glib/json-glib.h>
+
+/* {{{ Error handling */
+
+G_DEFINE_QUARK(pango-layout-serialize-error-quark, pango_layout_serialize_error)
+
+/* }}} */
+/* {{{ Serialization */
+
+static GType
+get_enum_type (PangoAttrType attr_type)
+{
+  switch ((int)attr_type)
+    {
+    case PANGO_ATTR_STYLE: return PANGO_TYPE_STYLE;
+    case PANGO_ATTR_WEIGHT: return PANGO_TYPE_WEIGHT;
+    case PANGO_ATTR_VARIANT: return PANGO_TYPE_VARIANT;
+    case PANGO_ATTR_STRETCH: return PANGO_TYPE_STRETCH;
+    case PANGO_ATTR_GRAVITY: return PANGO_TYPE_GRAVITY;
+    case PANGO_ATTR_GRAVITY_HINT: return PANGO_TYPE_GRAVITY_HINT;
+    case PANGO_ATTR_UNDERLINE: return PANGO_TYPE_UNDERLINE;
+    case PANGO_ATTR_OVERLINE: return PANGO_TYPE_OVERLINE;
+    case PANGO_ATTR_BASELINE_SHIFT: return PANGO_TYPE_BASELINE_SHIFT;
+    case PANGO_ATTR_FONT_SCALE: return PANGO_TYPE_FONT_SCALE;
+    case PANGO_ATTR_TEXT_TRANSFORM: return PANGO_TYPE_TEXT_TRANSFORM;
+    default: return G_TYPE_INVALID;
+    }
+}
+
+static void
+add_enum_value (JsonBuilder   *builder,
+                GType          type,
+                int            value,
+                gboolean       allow_extra)
+{
+  GEnumClass *enum_class;
+  GEnumValue *enum_value;
+
+  enum_class = g_type_class_ref (type);
+  enum_value = g_enum_get_value (enum_class, value);
+
+  if (enum_value)
+    json_builder_add_string_value (builder, enum_value->value_nick);
+  else if (allow_extra)
+    {
+      char buf[128];
+      g_snprintf (buf, 128, "%d", value);
+      json_builder_add_string_value (builder, buf);
+    }
+  else
+    json_builder_add_string_value (builder, "ERROR");
+
+}
+
+static void
+add_attribute (JsonBuilder    *builder,
+               PangoAttribute *attr)
+{
+  char *str;
+
+  json_builder_begin_object (builder);
+
+  if (attr->start_index != PANGO_ATTR_INDEX_FROM_TEXT_BEGINNING)
+    {
+      json_builder_set_member_name (builder, "start");
+      json_builder_add_int_value (builder, (int)attr->start_index);
+    }
+  if (attr->end_index != PANGO_ATTR_INDEX_TO_TEXT_END)
+    {
+      json_builder_set_member_name (builder, "end");
+      json_builder_add_int_value (builder, (int)attr->end_index);
+    }
+  json_builder_set_member_name (builder, "type");
+  add_enum_value (builder, PANGO_TYPE_ATTR_TYPE, attr->klass->type, FALSE);
+
+  json_builder_set_member_name (builder, "value");
+  switch (attr->klass->type)
+    {
+    default:
+    case PANGO_ATTR_INVALID:
+      g_assert_not_reached ();
+    case PANGO_ATTR_LANGUAGE:
+      json_builder_add_string_value (builder, pango_language_to_string (((PangoAttrLanguage*)attr)->value));
+      break;
+    case PANGO_ATTR_FAMILY:
+    case PANGO_ATTR_FONT_FEATURES:
+      json_builder_add_string_value (builder, ((PangoAttrString*)attr)->value);
+      break;
+    case PANGO_ATTR_STYLE:
+    case PANGO_ATTR_VARIANT:
+    case PANGO_ATTR_STRETCH:
+    case PANGO_ATTR_UNDERLINE:
+    case PANGO_ATTR_OVERLINE:
+    case PANGO_ATTR_GRAVITY:
+    case PANGO_ATTR_GRAVITY_HINT:
+    case PANGO_ATTR_TEXT_TRANSFORM:
+    case PANGO_ATTR_FONT_SCALE:
+      add_enum_value (builder, get_enum_type (attr->klass->type), ((PangoAttrInt*)attr)->value, FALSE);
+      break;
+    case PANGO_ATTR_WEIGHT:
+    case PANGO_ATTR_BASELINE_SHIFT:
+      add_enum_value (builder, get_enum_type (attr->klass->type), ((PangoAttrInt*)attr)->value, TRUE);
+      break;
+    case PANGO_ATTR_SIZE:
+    case PANGO_ATTR_RISE:
+    case PANGO_ATTR_LETTER_SPACING:
+    case PANGO_ATTR_ABSOLUTE_SIZE:
+    case PANGO_ATTR_FOREGROUND_ALPHA:
+    case PANGO_ATTR_BACKGROUND_ALPHA:
+    case PANGO_ATTR_SHOW:
+    case PANGO_ATTR_WORD:
+    case PANGO_ATTR_SENTENCE:
+    case PANGO_ATTR_ABSOLUTE_LINE_HEIGHT:
+      json_builder_add_int_value (builder, ((PangoAttrInt*)attr)->value);
+      break;
+    case PANGO_ATTR_FONT_DESC:
+      str = pango_font_description_to_string (((PangoAttrFontDesc*)attr)->desc);
+      json_builder_add_string_value (builder, str);
+      g_free (str);
+      break;
+    case PANGO_ATTR_FOREGROUND:
+    case PANGO_ATTR_BACKGROUND:
+    case PANGO_ATTR_UNDERLINE_COLOR:
+    case PANGO_ATTR_OVERLINE_COLOR:
+    case PANGO_ATTR_STRIKETHROUGH_COLOR:
+      str = pango_color_to_string (&((PangoAttrColor*)attr)->color);
+      json_builder_add_string_value (builder, str);
+      g_free (str);
+      break;
+    case PANGO_ATTR_STRIKETHROUGH:
+    case PANGO_ATTR_FALLBACK:
+    case PANGO_ATTR_ALLOW_BREAKS:
+    case PANGO_ATTR_INSERT_HYPHENS:
+      json_builder_add_boolean_value (builder, ((PangoAttrInt*)attr)->value != 0);
+      break;
+    case PANGO_ATTR_SHAPE:
+      json_builder_add_string_value (builder, "shape");
+      break;
+    case PANGO_ATTR_SCALE:
+    case PANGO_ATTR_LINE_HEIGHT:
+      json_builder_add_double_value (builder, ((PangoAttrFloat*)attr)->value);
+    }
+
+  json_builder_end_object (builder);
+}
+
+static void
+add_attr_list (JsonBuilder   *builder,
+               PangoAttrList *attrs)
+{
+  GSList *attributes, *l;
+
+  json_builder_begin_array (builder);
+
+  attributes = pango_attr_list_get_attributes (attrs);
+  for (l = attributes; l; l = l->next)
+    {
+      PangoAttribute *attr = l->data;
+      add_attribute (builder, attr);
+    }
+  g_slist_free_full (attributes, (GDestroyNotify) pango_attribute_destroy);
+
+  json_builder_end_array (builder);
+}
+
+static void
+add_tab_array (JsonBuilder   *builder,
+               PangoTabArray *tabs)
+{
+  json_builder_begin_object (builder);
+
+  json_builder_set_member_name (builder, "positions-in-pixels");
+  json_builder_add_boolean_value (builder, pango_tab_array_get_positions_in_pixels (tabs));
+  json_builder_set_member_name (builder, "positions");
+  json_builder_begin_array (builder);
+  for (int i = 0; i < pango_tab_array_get_size (tabs); i++)
+    {
+      int pos;
+      pango_tab_array_get_tab (tabs, i, NULL, &pos);
+      json_builder_add_int_value (builder, pos);
+    }
+  json_builder_end_array (builder);
+
+  json_builder_end_object (builder);
+}
+
+static JsonNode *
+layout_to_json (PangoLayout *layout)
+{
+  JsonBuilder *builder;
+  JsonNode *root;
+
+  builder = json_builder_new_immutable ();
+
+  json_builder_begin_object (builder);
+
+  json_builder_set_member_name (builder, "text");
+  json_builder_add_string_value (builder, layout->text);
+
+  if (layout->attrs)
+    {
+      json_builder_set_member_name (builder, "attributes");
+      add_attr_list (builder, layout->attrs);
+    }
+
+  if (layout->font_desc)
+    {
+      char *str = pango_font_description_to_string (layout->font_desc);
+      json_builder_set_member_name (builder, "font");
+      json_builder_add_string_value (builder, str);
+      g_free (str);
+    }
+
+  if (layout->tabs)
+    {
+      json_builder_set_member_name (builder, "tabs");
+      add_tab_array (builder, layout->tabs);
+    }
+
+  if (layout->justify)
+    {
+      json_builder_set_member_name (builder, "justify");
+      json_builder_add_boolean_value (builder, TRUE);
+    }
+
+  if (layout->justify_last_line)
+    {
+      json_builder_set_member_name (builder, "justify-last-line");
+      json_builder_add_boolean_value (builder, TRUE);
+    }
+
+  if (layout->single_paragraph)
+    {
+      json_builder_set_member_name (builder, "single-paragraph");
+      json_builder_add_boolean_value (builder, TRUE);
+    }
+
+  if (!layout->auto_dir)
+    {
+      json_builder_set_member_name (builder, "auto-dir");
+      json_builder_add_boolean_value (builder, FALSE);
+    }
+
+  if (layout->alignment != PANGO_ALIGN_LEFT)
+    {
+      json_builder_set_member_name (builder, "alignment");
+      add_enum_value (builder, PANGO_TYPE_ALIGNMENT, layout->alignment, FALSE);
+    }
+
+  if (layout->wrap != PANGO_WRAP_WORD)
+    {
+      json_builder_set_member_name (builder, "wrap");
+      add_enum_value (builder, PANGO_TYPE_WRAP_MODE, layout->wrap, FALSE);
+    }
+
+  if (layout->ellipsize != PANGO_ELLIPSIZE_NONE)
+    {
+      json_builder_set_member_name (builder, "ellipsize");
+      add_enum_value (builder, PANGO_TYPE_ELLIPSIZE_MODE, layout->ellipsize, FALSE);
+    }
+
+  if (layout->width != -1)
+    {
+      json_builder_set_member_name (builder, "width");
+      json_builder_add_int_value (builder, layout->width);
+    }
+
+  if (layout->height != -1)
+    {
+      json_builder_set_member_name (builder, "height");
+      json_builder_add_int_value (builder, layout->height);
+    }
+
+  if (layout->indent != 0)
+    {
+      json_builder_set_member_name (builder, "indent");
+      json_builder_add_int_value (builder, layout->indent);
+    }
+
+  if (layout->spacing != 0)
+    {
+      json_builder_set_member_name (builder, "spacing");
+      json_builder_add_int_value (builder, layout->spacing);
+    }
+
+  if (layout->line_spacing != 0.)
+    {
+      json_builder_set_member_name (builder, "line-spacing");
+      json_builder_add_double_value (builder, layout->line_spacing);
+    }
+
+  json_builder_end_object (builder);
+
+  root = json_builder_get_root (builder);
+  g_object_unref (builder);
+
+  return root;
+}
+
+/* }}} */
+/* {{{ Deserialization */
+
+static int
+get_enum_value (GType       type,
+                const char *str,
+                gboolean    allow_extra)
+{
+  GEnumClass *enum_class;
+  GEnumValue *enum_value;
+
+  enum_class = g_type_class_ref (type);
+  enum_value = g_enum_get_value_by_nick (enum_class, str);
+
+  if (enum_value)
+    return enum_value->value;
+
+  if (allow_extra)
+    {
+      gint64 value;
+      char *endp;
+
+      value = g_ascii_strtoll (str, &endp, 10);
+      if (*endp == '\0')
+        return value;
+    }
+
+  return -1;
+}
+
+static PangoAttribute *
+json_to_attribute (JsonReader  *reader,
+                   GError     **error)
+{
+  PangoAttribute *attr = NULL;
+  PangoAttrType type = PANGO_ATTR_INVALID;
+  guint start = PANGO_ATTR_INDEX_FROM_TEXT_BEGINNING;
+  guint end = PANGO_ATTR_INDEX_TO_TEXT_END;
+  PangoFontDescription *desc;
+  PangoColor color;
+
+  if (!json_reader_is_object (reader))
+    {
+      g_set_error (error,
+                   PANGO_LAYOUT_SERIALIZE_ERROR, PANGO_LAYOUT_SERIALIZE_INVALID_SYNTAX,
+                   "Attribute must be a Json object");
+      return NULL;
+    }
+
+  if (json_reader_read_member (reader, "start"))
+    start = json_reader_get_int_value (reader);
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "end"))
+    end = json_reader_get_int_value (reader);
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "type"))
+    {
+      type = get_enum_value (PANGO_TYPE_ATTR_TYPE, json_reader_get_string_value (reader), FALSE);
+      if (type == -1 || type == PANGO_ATTR_INVALID)
+        {
+          g_set_error (error,
+                       PANGO_LAYOUT_SERIALIZE_ERROR, PANGO_LAYOUT_SERIALIZE_INVALID_VALUE,
+                       "Attribute \"type\" invalid: %s",
+                       json_reader_get_string_value (reader));
+          return NULL;
+        }
+      json_reader_end_member (reader);
+    }
+  else
+    {
+      g_set_error (error,
+                   PANGO_LAYOUT_SERIALIZE_ERROR, PANGO_LAYOUT_SERIALIZE_MISSING_VALUE,
+                   "Attribute \"type\" missing");
+      json_reader_end_member (reader);
+      return NULL;
+    }
+
+  if (!json_reader_read_member (reader, "value"))
+    {
+      g_set_error (error,
+                   PANGO_LAYOUT_SERIALIZE_ERROR, PANGO_LAYOUT_SERIALIZE_MISSING_VALUE,
+                   "Attribute \"value\" missing");
+      json_reader_end_member (reader);
+      return NULL;
+    }
+
+  switch (type)
+    {
+    default:
+    case PANGO_ATTR_INVALID:
+      g_assert_not_reached ();
+
+    case PANGO_ATTR_LANGUAGE:
+      attr = pango_attr_language_new (pango_language_from_string (json_reader_get_string_value (reader)));
+      break;
+    case PANGO_ATTR_FAMILY:
+      attr = pango_attr_family_new (json_reader_get_string_value (reader));
+      break;
+    case PANGO_ATTR_STYLE:
+      attr = pango_attr_style_new (get_enum_value (PANGO_TYPE_STYLE, json_reader_get_string_value (reader), FALSE));
+      break;
+    case PANGO_ATTR_WEIGHT:
+      attr = pango_attr_weight_new (get_enum_value (PANGO_TYPE_WEIGHT, json_reader_get_string_value (reader), TRUE));
+      break;
+    case PANGO_ATTR_VARIANT:
+      attr = pango_attr_variant_new (get_enum_value (PANGO_TYPE_VARIANT, json_reader_get_string_value (reader), FALSE));
+      break;
+    case PANGO_ATTR_STRETCH:
+      attr = pango_attr_stretch_new (get_enum_value (PANGO_TYPE_STRETCH, json_reader_get_string_value (reader), FALSE));
+      break;
+    case PANGO_ATTR_SIZE:
+      attr = pango_attr_size_new (json_reader_get_int_value (reader));
+      break;
+    case PANGO_ATTR_FONT_DESC:
+      desc = pango_font_description_from_string (json_reader_get_string_value (reader));
+      attr = pango_attr_font_desc_new (desc);
+      pango_font_description_free (desc);
+      break;
+    case PANGO_ATTR_FOREGROUND:
+      pango_color_parse (&color, json_reader_get_string_value (reader));
+      attr = pango_attr_foreground_new (color.red, color.green, color.blue);
+      break;
+    case PANGO_ATTR_BACKGROUND:
+      pango_color_parse (&color, json_reader_get_string_value (reader));
+      attr = pango_attr_background_new (color.red, color.green, color.blue);
+      break;
+    case PANGO_ATTR_UNDERLINE:
+      attr = pango_attr_underline_new (get_enum_value (PANGO_TYPE_UNDERLINE, json_reader_get_string_value (reader), FALSE));
+      break;
+    case PANGO_ATTR_STRIKETHROUGH:
+      attr = pango_attr_strikethrough_new (json_reader_get_boolean_value (reader));
+      break;
+    case PANGO_ATTR_RISE:
+      attr = pango_attr_rise_new (json_reader_get_int_value (reader));
+      break;
+    case PANGO_ATTR_SHAPE:
+      /* FIXME */
+      attr = pango_attr_shape_new (&(PangoRectangle) { 0, 0, 0, 0}, &(PangoRectangle) { 0, 0, 0, 0});
+      break;
+    case PANGO_ATTR_SCALE:
+      attr = pango_attr_scale_new (json_reader_get_double_value (reader));
+      break;
+    case PANGO_ATTR_FALLBACK:
+      attr = pango_attr_fallback_new (json_reader_get_boolean_value (reader));
+      break;
+    case PANGO_ATTR_LETTER_SPACING:
+      attr = pango_attr_letter_spacing_new (json_reader_get_int_value (reader));
+      break;
+    case PANGO_ATTR_UNDERLINE_COLOR:
+      pango_color_parse (&color, json_reader_get_string_value (reader));
+      attr = pango_attr_underline_color_new (color.red, color.green, color.blue);
+      break;
+    case PANGO_ATTR_STRIKETHROUGH_COLOR:
+      pango_color_parse (&color, json_reader_get_string_value (reader));
+      attr = pango_attr_strikethrough_color_new (color.red, color.green, color.blue);
+      break;
+    case PANGO_ATTR_ABSOLUTE_SIZE:
+      attr = pango_attr_size_new_absolute (json_reader_get_int_value (reader));
+      break;
+    case PANGO_ATTR_GRAVITY:
+      attr = pango_attr_gravity_new (get_enum_value (PANGO_TYPE_GRAVITY, json_reader_get_string_value (reader), FALSE));
+      break;
+    case PANGO_ATTR_GRAVITY_HINT:
+      attr = pango_attr_gravity_hint_new (get_enum_value (PANGO_TYPE_GRAVITY_HINT, json_reader_get_string_value (reader), FALSE));
+      break;
+    case PANGO_ATTR_FONT_FEATURES:
+      attr = pango_attr_font_features_new (json_reader_get_string_value (reader));
+      break;
+    case PANGO_ATTR_FOREGROUND_ALPHA:
+      attr = pango_attr_foreground_alpha_new (json_reader_get_int_value (reader));
+      break;
+    case PANGO_ATTR_BACKGROUND_ALPHA:
+      attr = pango_attr_background_alpha_new (json_reader_get_int_value (reader));
+      break;
+    case PANGO_ATTR_ALLOW_BREAKS:
+      attr = pango_attr_allow_breaks_new (json_reader_get_boolean_value (reader));
+      break;
+    case PANGO_ATTR_SHOW:
+      attr = pango_attr_show_new (json_reader_get_int_value (reader));
+      break;
+    case PANGO_ATTR_INSERT_HYPHENS:
+      attr = pango_attr_insert_hyphens_new (json_reader_get_boolean_value (reader));
+      break;
+    case PANGO_ATTR_OVERLINE:
+      attr = pango_attr_overline_new (get_enum_value (PANGO_TYPE_OVERLINE, json_reader_get_string_value (reader), FALSE));
+      break;
+    case PANGO_ATTR_OVERLINE_COLOR:
+      pango_color_parse (&color, json_reader_get_string_value (reader));
+      attr = pango_attr_overline_color_new (color.red, color.green, color.blue);
+      break;
+    case PANGO_ATTR_LINE_HEIGHT:
+      attr = pango_attr_line_height_new (json_reader_get_double_value (reader));
+      break;
+    case PANGO_ATTR_ABSOLUTE_LINE_HEIGHT:
+      attr = pango_attr_line_height_new_absolute (json_reader_get_int_value (reader));
+      break;
+    case PANGO_ATTR_TEXT_TRANSFORM:
+      attr = pango_attr_text_transform_new (get_enum_value (PANGO_TYPE_TEXT_TRANSFORM, json_reader_get_string_value (reader), FALSE));
+      break;
+    case PANGO_ATTR_WORD:
+      attr = pango_attr_word_new ();
+      break;
+    case PANGO_ATTR_SENTENCE:
+      attr = pango_attr_sentence_new ();
+      break;
+    case PANGO_ATTR_BASELINE_SHIFT:
+      attr = pango_attr_baseline_shift_new (get_enum_value (PANGO_TYPE_BASELINE_SHIFT, json_reader_get_string_value (reader), TRUE));
+      break;
+    case PANGO_ATTR_FONT_SCALE:
+      attr = pango_attr_font_scale_new (get_enum_value (PANGO_TYPE_BASELINE_SHIFT, json_reader_get_string_value (reader), FALSE));
+      break;
+    }
+
+  attr->start_index = start;
+  attr->end_index = end;
+
+  json_reader_end_member (reader);
+
+  return attr;
+}
+
+static PangoAttrList *
+json_to_attr_list (JsonReader  *reader,
+                   GError     **error)
+{
+  PangoAttrList *attributes;
+
+  if (!json_reader_is_array (reader))
+    {
+      g_set_error (error,
+                   PANGO_LAYOUT_SERIALIZE_ERROR, PANGO_LAYOUT_SERIALIZE_INVALID_SYNTAX,
+                   "\"attributes\" must be a Json array");
+      goto fail;
+    }
+
+  attributes = pango_attr_list_new ();
+
+  for (int i = 0; i < json_reader_count_elements (reader); i++)
+    {
+      PangoAttribute *attr;
+      json_reader_read_element (reader, i);
+      attr = json_to_attribute (reader, error);
+      if (!attr)
+        goto fail;
+      pango_attr_list_insert (attributes, attr);
+      json_reader_end_element (reader);
+    }
+
+  return attributes;
+
+fail:
+  if (attributes)
+    pango_attr_list_unref (attributes);
+  return NULL;
+}
+
+static PangoTabArray *
+json_to_tab_array (JsonReader  *reader,
+                   GError     **error)
+{
+  PangoTabArray *tabs;
+  gboolean positions_in_pixels = FALSE;
+
+  if (json_reader_read_member (reader, "positions-in-pixels"))
+    positions_in_pixels = json_reader_get_boolean_value (reader);
+  json_reader_end_member (reader);
+
+  tabs = pango_tab_array_new (0, positions_in_pixels);
+
+  if (json_reader_read_member (reader, "positions"))
+    {
+      if (!json_reader_is_array (reader))
+        {
+          g_set_error (error,
+                       PANGO_LAYOUT_SERIALIZE_ERROR,
+                       PANGO_LAYOUT_SERIALIZE_INVALID_SYNTAX,
+                       "Tab \"positions\"  must be a Json array");
+          goto fail;
+        }
+
+      pango_tab_array_resize (tabs, json_reader_count_elements (reader));
+      for (int i = 0; i < json_reader_count_elements (reader); i++)
+        {
+          int pos;
+          json_reader_read_element (reader, i);
+          pos = json_reader_get_int_value (reader);
+          pango_tab_array_set_tab (tabs, i, PANGO_TAB_LEFT, pos);
+          json_reader_end_element (reader);
+        }
+    }
+  json_reader_end_member (reader);
+
+  return tabs;
+
+fail:
+  if (tabs)
+    pango_tab_array_free (tabs);
+  return NULL;
+}
+
+static PangoLayout *
+json_to_layout (PangoContext *context,
+                JsonNode     *node,
+                GError      **error)
+{
+  JsonReader *reader;
+  PangoLayout *layout;
+
+  layout = pango_layout_new (context);
+
+  reader = json_reader_new (node);
+  if (!json_reader_is_object (reader))
+    {
+      g_set_error (error,
+                   PANGO_LAYOUT_SERIALIZE_ERROR,
+                   PANGO_LAYOUT_SERIALIZE_INVALID_SYNTAX,
+                   "Layout must be a Json object");
+      goto fail;
+    }
+
+  if (json_reader_read_member (reader, "text"))
+    pango_layout_set_text (layout, json_reader_get_string_value (reader), -1);
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "attributes"))
+    {
+      PangoAttrList *attributes;
+
+      attributes = json_to_attr_list (reader, error);
+
+      if (!attributes)
+        goto fail;
+
+      pango_layout_set_attributes (layout, attributes);
+      pango_attr_list_unref (attributes);
+    }
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "font"))
+    {
+      PangoFontDescription *desc;
+
+      desc = pango_font_description_from_string ( json_reader_get_string_value (reader));
+      if (!desc)
+        {
+          g_set_error (error,
+                       PANGO_LAYOUT_SERIALIZE_ERROR,
+                       PANGO_LAYOUT_SERIALIZE_INVALID_VALUE,
+                       "Could not parse \"font\" value: %s",
+                       json_reader_get_string_value (reader));
+          goto fail;
+        }
+      pango_layout_set_font_description (layout, desc);
+      pango_font_description_free (desc);
+    }
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "tabs"))
+    {
+      PangoTabArray *tabs;
+
+      tabs = json_to_tab_array (reader, error);
+
+      if (!tabs)
+        goto fail;
+
+      pango_layout_set_tabs (layout, tabs);
+      pango_tab_array_free (tabs);
+    }
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "justify"))
+    pango_layout_set_justify (layout, json_reader_get_boolean_value (reader));
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "justify-last-line"))
+    pango_layout_set_justify_last_line (layout, json_reader_get_boolean_value (reader));
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "single-paragraph"))
+    pango_layout_set_single_paragraph_mode (layout, json_reader_get_boolean_value (reader));
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "auto-dir"))
+    pango_layout_set_auto_dir (layout, json_reader_get_boolean_value (reader));
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "alignment"))
+    {
+      PangoAlignment align = get_enum_value (PANGO_TYPE_ALIGNMENT,
+                                             json_reader_get_string_value (reader),
+                                             FALSE);
+      if (align == -1)
+        {
+          g_set_error (error,
+                       PANGO_LAYOUT_SERIALIZE_ERROR,
+                       PANGO_LAYOUT_SERIALIZE_INVALID_VALUE,
+                       "Could not parse \"alignment\" value: %s",
+                       json_reader_get_string_value (reader));
+          goto fail;
+        }
+
+      pango_layout_set_alignment (layout, align);
+    }
+
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "wrap"))
+    {
+      PangoWrapMode wrap = get_enum_value (PANGO_TYPE_WRAP_MODE,
+                                           json_reader_get_string_value (reader),
+                                           FALSE);
+
+      if (wrap == -1)
+        {
+          g_set_error (error,
+                       PANGO_LAYOUT_SERIALIZE_ERROR,
+                       PANGO_LAYOUT_SERIALIZE_INVALID_VALUE,
+                       "Could not parse \"wrap\" value: %s",
+                       json_reader_get_string_value (reader));
+          goto fail;
+        }
+
+      pango_layout_set_wrap (layout, wrap);
+    }
+
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "ellipsize"))
+    {
+      PangoEllipsizeMode ellipsize = get_enum_value (PANGO_TYPE_ELLIPSIZE_MODE,
+                                                     json_reader_get_string_value (reader),
+                                                     FALSE);
+
+      if (ellipsize == -1)
+        {
+          g_set_error (error,
+                       PANGO_LAYOUT_SERIALIZE_ERROR,
+                       PANGO_LAYOUT_SERIALIZE_INVALID_VALUE,
+                       "Could not parse \"ellipsize\" value: %s",
+                       json_reader_get_string_value (reader));
+          goto fail;
+        }
+
+      pango_layout_set_ellipsize (layout, ellipsize);
+    }
+
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "width"))
+    pango_layout_set_width (layout, json_reader_get_int_value (reader));
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "height"))
+    pango_layout_set_height (layout, json_reader_get_int_value (reader));
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "indent"))
+    pango_layout_set_indent (layout, json_reader_get_int_value (reader));
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "spacing"))
+    pango_layout_set_spacing (layout, json_reader_get_int_value (reader));
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "line-spacing"))
+    pango_layout_set_line_spacing (layout, json_reader_get_double_value (reader));
+  json_reader_end_member (reader);
+
+  g_object_unref (reader);
+
+  return layout;
+
+fail:
+  g_object_unref (reader);
+  g_object_unref (layout);
+  return NULL;
+}
+
+ /* }}} */
+ /* {{{ Public API */
+
+/**
+ * pango_layout_serialize:
+ * @layout: a `PangoLayout`
+ *
+ * Serializes the @layout for later deserialization via [method@Pango.Layout.deserialize].
+ *
+ * There are no guarantees about the format of the output accross different
+ * versions of Pango and [method@Pango.Layout.deserialize] will reject data
+ * that it cannot parse.
+ *
+ * The intended use of this function is testing, benchmarking and debugging.
+ * The format is not meant as a permanent storage format.
+ *
+ * Returns: a `GBytes` containing the serialized form of @layout
+ *
+ * Since: 1.50
+ */
+GBytes *
+pango_layout_serialize (PangoLayout *layout)
+{
+  JsonGenerator *generator;
+  JsonNode *node;
+  char *data;
+  gsize size;
+
+  node = layout_to_json (layout);
+
+  generator = json_generator_new ();
+  json_generator_set_pretty (generator, TRUE);
+  json_generator_set_indent (generator, 2);
+
+  json_generator_set_root (generator, node);
+  data = json_generator_to_data (generator, &size);
+
+  json_node_free (node);
+  g_object_unref (generator);
+
+  return g_bytes_new_take (data, size);
+}
+
+/**
+ * pango_layout_write_to_file:
+ * @layout: a `PangoLayout`
+ * @filename: (type filename): the file to save it to
+ * @error: Return location for a potential error
+ *
+ * This function is equivalent to calling [method@Pango.Layout.serialize]
+ * followed by g_file_set_contents().
+ *
+ * See those two functions for details on the arguments.
+ *
+ * It is mostly intended for use inside a debugger to quickly dump
+ * a layout to a file for later inspection.
+ *
+ * Returns: %TRUE if saving was successful
+ *
+ * Since: 1.50
+ */
+gboolean
+pango_layout_write_to_file (PangoLayout  *layout,
+                            const char   *filename,
+                            GError      **error)
+{
+  GBytes *bytes;
+  gboolean result;
+
+  g_return_val_if_fail (PANGO_IS_LAYOUT (layout), FALSE);
+  g_return_val_if_fail (filename != NULL, FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  bytes = pango_layout_serialize (layout);
+  result = g_file_set_contents (filename,
+                                g_bytes_get_data (bytes, NULL),
+                                g_bytes_get_size (bytes),
+                                error);
+  g_bytes_unref (bytes);
+
+  return result;
+
+}
+
+/**
+ * pango_layout_deserialize:
+ * @context: a `PangoContext`
+ * @bytes: the bytes containing the data
+ * @error: return location for an error
+ *
+ * Loads data previously created via [method@Pango.Layout.serialize].
+ *
+ * For a discussion of the supported format, see that function.
+ *
+ * Returns: (nullable) (transfer full): a new `PangoLayout`
+ *
+ * Since: 1.50
+ */
+PangoLayout *
+pango_layout_deserialize (PangoContext  *context,
+                          GBytes        *bytes,
+                          GError       **error)
+{
+  JsonParser *parser;
+  JsonNode *node;
+  PangoLayout *layout;
+
+  parser = json_parser_new_immutable ();
+  if (!json_parser_load_from_data (parser,
+                                   g_bytes_get_data (bytes, NULL),
+                                   g_bytes_get_size (bytes),
+                                   error))
+    {
+      g_object_unref (parser);
+      return NULL;
+    }
+
+  node = json_parser_get_root (parser);
+  layout = json_to_layout (context, node, error);
+
+  g_object_unref (parser);
+
+  return layout;
+}
+
+/* }}} */
+
+/* vim:set foldmethod=marker expandtab: */
diff --git a/tests/testserialize.c b/tests/testserialize.c
index cc6c67bc..2c1d2f53 100644
--- a/tests/testserialize.c
+++ b/tests/testserialize.c
@@ -21,6 +21,7 @@
 #include "config.h"
 #include <glib.h>
 #include <pango/pangocairo.h>
+#include <gio/gio.h>
 
 static void
 test_serialize_attr_list (void)
@@ -122,6 +123,168 @@ test_serialize_tab_array (void)
     }
 }
 
+static void
+test_serialize_layout_minimal (void)
+{
+  const char *test =
+    "{\n"
+    "  \"text\" : \"Almost nothing\"\n"
+    "}";
+
+  PangoContext *context;
+  GBytes *bytes;
+  PangoLayout *layout;
+  GError *error = NULL;
+  GBytes *out_bytes;
+  const char *str;
+
+  context = pango_font_map_create_context (pango_cairo_font_map_get_default ());
+
+  bytes = g_bytes_new_static (test, -1);
+
+  layout = pango_layout_deserialize (context, bytes, &error);
+  g_assert_no_error (error);
+  g_assert_true (PANGO_IS_LAYOUT (layout));
+  g_assert_cmpstr (pango_layout_get_text (layout), ==, "Almost nothing");
+  g_assert_null (pango_layout_get_attributes (layout));
+  g_assert_null (pango_layout_get_tabs (layout));
+  g_assert_null (pango_layout_get_font_description (layout));
+  g_assert_cmpint (pango_layout_get_alignment (layout), ==, PANGO_ALIGN_LEFT);
+  g_assert_cmpint (pango_layout_get_width (layout), ==, -1);
+
+  out_bytes = pango_layout_serialize (layout);
+  str = g_bytes_get_data (out_bytes, NULL);
+
+  g_assert_cmpstr (str, ==, test);
+
+  g_bytes_unref (out_bytes);
+
+  g_object_unref (layout);
+  g_bytes_unref (bytes);
+  g_object_unref (context);
+}
+
+static void
+test_serialize_layout_valid (void)
+{
+  const char *test =
+    "{\n"
+    "  \"text\" : \"Some fun with layouts!\",\n"
+    "  \"attributes\" : [\n"
+    "    {\n"
+    "      \"end\" : 4,\n"
+    "      \"type\" : \"foreground\",\n"
+    "      \"value\" : \"#ffff00000000\"\n"
+    "    },\n"
+    "    {\n"
+    "      \"start\" : 5,\n"
+    "      \"end\" : 8,\n"
+    "      \"type\" : \"foreground\",\n"
+    "      \"value\" : \"#000080800000\"\n"
+    "    },\n"
+    "    {\n"
+    "      \"start\" : 14,\n"
+    "      \"type\" : \"foreground\",\n"
+    "      \"value\" : \"#ffff0000ffff\"\n"
+    "    }\n"
+    "  ],\n"
+    "  \"font\" : \"Sans Bold 32\",\n"
+    "  \"tabs\" : {\n"
+    "    \"positions-in-pixels\" : true,\n"
+    "    \"positions\" : [\n"
+    "      0,\n"
+    "      50,\n"
+    "      100\n"
+    "    ]\n"
+    "  },\n"
+    "  \"alignment\" : \"center\",\n"
+    "  \"width\" : 350000,\n"
+    "  \"line-spacing\" : 1.5\n"
+    "}";
+
+  PangoContext *context;
+  GBytes *bytes;
+  PangoLayout *layout;
+  PangoTabArray *tabs;
+  GError *error = NULL;
+  GBytes *out_bytes;
+  const char *str;
+  char *s;
+
+  context = pango_font_map_create_context (pango_cairo_font_map_get_default ());
+
+  bytes = g_bytes_new_static (test, -1);
+
+  layout = pango_layout_deserialize (context, bytes, &error);
+  g_assert_no_error (error);
+  g_assert_true (PANGO_IS_LAYOUT (layout));
+  g_assert_cmpstr (pango_layout_get_text (layout), ==, "Some fun with layouts!");
+  g_assert_nonnull (pango_layout_get_attributes (layout));
+  tabs = pango_layout_get_tabs (layout);
+  g_assert_nonnull (tabs);
+  pango_tab_array_free (tabs);
+  s = pango_font_description_to_string (pango_layout_get_font_description (layout));
+  g_assert_cmpstr (s, ==, "Sans Bold 32");
+  g_free (s);
+  g_assert_cmpint (pango_layout_get_alignment (layout), ==, PANGO_ALIGN_CENTER);
+  g_assert_cmpint (pango_layout_get_width (layout), ==, 350000);
+  g_assert_cmpfloat_with_epsilon (pango_layout_get_line_spacing (layout), 1.5, 0.0001);
+
+  out_bytes = pango_layout_serialize (layout);
+  str = g_bytes_get_data (out_bytes, NULL);
+
+  g_assert_cmpstr (str, ==, test);
+
+  g_bytes_unref (out_bytes);
+
+  g_object_unref (layout);
+  g_bytes_unref (bytes);
+  g_object_unref (context);
+}
+
+static void
+test_serialize_layout_invalid (void)
+{
+  const char *test1 =
+    "{\n"
+    "  \"attributes\" : [\n"
+    "    {\n"
+    "      \"type\" : \"caramba\"\n"
+    "    }\n"
+    "  ]\n"
+    "}";
+
+  const char *test2 =
+    "{\n"
+    "  \"attributes\" : [\n"
+    "    {\n"
+    "      \"type\" : \"weight\"\n"
+    "    }\n"
+    "  ]\n"
+    "}";
+
+  PangoContext *context;
+  GBytes *bytes;
+  PangoLayout *layout;
+  GError *error = NULL;
+
+  context = pango_font_map_create_context (pango_cairo_font_map_get_default ());
+
+  bytes = g_bytes_new_static (test1, -1);
+  layout = pango_layout_deserialize (context, bytes, &error);
+  g_assert_null (layout);
+  g_assert_error (error, PANGO_LAYOUT_SERIALIZE_ERROR, PANGO_LAYOUT_SERIALIZE_INVALID_VALUE);
+  g_bytes_unref (bytes);
+  g_clear_error (&error);
+
+  bytes = g_bytes_new_static (test2, -1);
+  layout = pango_layout_deserialize (context, bytes, &error);
+  g_assert_null (layout);
+  g_assert_error (error, PANGO_LAYOUT_SERIALIZE_ERROR, PANGO_LAYOUT_SERIALIZE_MISSING_VALUE);
+  g_bytes_unref (bytes);
+
+  g_object_unref (context);
+}
 int
 main (int argc, char *argv[])
 {
@@ -129,6 +292,9 @@ main (int argc, char *argv[])
 
   g_test_add_func ("/serialize/attr-list", test_serialize_attr_list);
   g_test_add_func ("/serialize/tab-array", test_serialize_tab_array);
+  g_test_add_func ("/serialize/layout/minimal", test_serialize_layout_minimal);
+  g_test_add_func ("/serialize/layout/valid", test_serialize_layout_valid);
+  g_test_add_func ("/serialize/layout/invalid", test_serialize_layout_invalid);
 
   return g_test_run ();
 }