Add serialization api

3 files changed, 302 insertions, 0 deletions

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-layout.h b/pango/pango-layout.h
index e28f9295..432d111f 100644
--- a/pango/pango-layout.h
+++ b/pango/pango-layout.h
@@ -351,6 +351,11 @@ GSList *         pango_layout_get_lines            (PangoLayout    *layout);
 PANGO_AVAILABLE_IN_1_16
 GSList *         pango_layout_get_lines_readonly   (PangoLayout    *layout);
 
+PANGO_AVAILABLE_IN_1_50
+GBytes *        pango_layout_serialize             (PangoLayout    *layout);
+PANGO_AVAILABLE_IN_1_50
+PangoLayout *   pango_layout_deserialize           (PangoContext   *context,
+                                                    GBytes         *bytes);
 
 #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..cb720d8d
--- /dev/null
+++ b/pango/serializer.c
@@ -0,0 +1,296 @@
+/* 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 <pango/pango-layout.h>
+#include <pango/pango-layout-private.h>
+#include <pango/pango-enum-types.h>
+
+typedef struct
+{
+  int indentation_level;
+  GString *str;
+} Printer;
+
+static void
+printer_init (Printer *self)
+{
+  self->indentation_level = 0;
+  self->str = g_string_new (NULL);
+}
+
+#define IDENT_LEVEL 2 /* Spaces per level */
+static void
+_indent (Printer *self)
+{
+  if (self->indentation_level > 0)
+    g_string_append_printf (self->str, "%*s", self->indentation_level * IDENT_LEVEL, " ");
+}
+#undef IDENT_LEVEL
+
+static void
+start_node (Printer    *self,
+            const char *node_name)
+{
+  g_string_append_printf (self->str, "%s {\n", node_name);
+  self->indentation_level ++;
+}
+
+static void
+end_node (Printer *self)
+{
+  self->indentation_level --;
+  _indent (self);
+  g_string_append (self->str, "}\n");
+}
+
+static void
+print_string (GString    *str,
+              const char *string,
+              gboolean    multiline)
+{
+  gsize len;
+
+  g_return_if_fail (str != NULL);
+  g_return_if_fail (string != NULL);
+
+  g_string_append_c (str, '"');
+
+  do {
+    len = strcspn (string, "\\\"\n\r\f");
+    g_string_append_len (str, string, len);
+    string += len;
+    switch (*string)
+      {
+      case '\0':
+        goto out;
+      case '\n':
+        if (multiline)
+          g_string_append (str, "\\A\\\n");
+        else
+          g_string_append (str, "\\A ");
+        break;
+      case '\r':
+        g_string_append (str, "\\D ");
+        break;
+      case '\f':
+        g_string_append (str, "\\C ");
+        break;
+      case '\"':
+        g_string_append (str, "\\\"");
+        break;
+      case '\\':
+        g_string_append (str, "\\\\");
+        break;
+      default:
+        g_assert_not_reached ();
+        break;
+      }
+    string++;
+  } while (*string);
+
+out:
+  g_string_append_c (str, '"');
+}
+
+static void
+append_string_param (Printer    *p,
+                     const char *param_name,
+                     const char *value)
+{
+  _indent (p);
+  g_string_append (p->str, param_name);
+  g_string_append (p->str, ": ");
+  print_string (p->str, value, TRUE);
+  g_string_append_c (p->str, ';');
+  g_string_append_c (p->str, '\n');
+}
+
+static void
+append_simple_string (Printer    *p,
+                      const char *param_name,
+                      const char *value)
+{
+  _indent (p);
+  g_string_append (p->str, param_name);
+  g_string_append (p->str, ": ");
+  g_string_append (p->str, value ? "true" : "false");
+  g_string_append_c (p->str, ';');
+  g_string_append_c (p->str, '\n');
+}
+
+static void
+append_bool_param (Printer    *p,
+                   const char *param_name,
+                   gboolean    value)
+{
+  append_simple_string (p, param_name, value ? "true" : "false");
+}
+
+static void
+append_enum_param (Printer    *p,
+                   const char *param_name,
+                   GType       type,
+                   int         value)
+{
+  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)
+    {
+      append_simple_string (p, param_name, enum_value->value_nick);
+    }
+  else
+    {
+      char *v = g_strdup_printf ("%d", value);
+      append_simple_string (p, param_name, v);
+      g_free (v);
+    }
+
+  g_type_class_unref (enum_class);
+}
+
+static void
+append_int_param (Printer    *p,
+                  const char *param_name,
+                  int         value)
+{
+  char *v = g_strdup_printf ("%d", value);
+  append_simple_string (p, param_name, v);
+  g_free (v);
+}
+
+static void
+append_float_param (Printer    *p,
+                    const char *param_name,
+                    float       value)
+{
+  char buf[G_ASCII_DTOSTR_BUF_SIZE];
+  g_ascii_formatd (buf, G_ASCII_DTOSTR_BUF_SIZE, "%g", (double)value);
+  append_simple_string (p, param_name, buf);
+}
+
+static void
+append_attributes (Printer       *p,
+                   const char    *param_name,
+                   PangoAttrList *attrs)
+{
+}
+
+static void
+append_font_description (Printer              *p,
+                         const char           *param_name,
+                         PangoFontDescription *desc)
+{
+  char *value = pango_font_description_to_string (desc);
+  append_string_param (p, param_name, value);
+  g_free (value);
+}
+
+static void
+append_tab_array (Printer       *p,
+                  const char    *param_name,
+                  PangoTabArray *tabs)
+{
+}
+
+static void
+layout_print (Printer     *p,
+              PangoLayout *layout)
+{
+  start_node (p, "PangoLayout");
+
+  append_string_param (p, "text", layout->text);
+  append_attributes (p, "attributes", layout->attrs);
+  append_font_description (p, "font", layout->font_desc);
+  append_tab_array (p, "tabs", layout->tabs);
+  append_bool_param (p, "justify", layout->justify);
+  append_bool_param (p, "justify-last-line", layout->justify_last_line);
+  append_bool_param (p, "single-paragraph", layout->single_paragraph);
+  append_bool_param (p, "autodir", layout->auto_dir);
+  append_enum_param (p, "alignment", PANGO_TYPE_ALIGNMENT, layout->alignment);
+  append_enum_param (p, "wrap", PANGO_TYPE_WRAP_MODE, layout->wrap);
+  append_enum_param (p, "ellipsize", PANGO_TYPE_ELLIPSIZE_MODE, layout->wrap);
+  append_int_param (p, "width", layout->width);
+  append_int_param (p, "height", layout->width);
+  append_int_param (p, "indent", layout->indent);
+  append_int_param (p, "spacing", layout->spacing);
+  append_float_param (p, "line_spacing", layout->line_spacing);
+
+  end_node (p);
+}
+
+/* {{{ 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)
+{
+  Printer p;
+
+  printer_init (&p);
+
+  layout_print (&p, layout);
+
+  return g_string_free_to_bytes (p.str);
+}
+
+/**
+ * pango_layout_deserialize:
+ * @context: a `PangoContext`
+ * @bytes: the bytes containing the data
+ *
+ * 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)
+{
+  return NULL;
+}
+
+/* }}} */
+
+/* vim:set foldmethod=marker expandtab: */