[pango/serialization-improvements: 6/19] Allow serializing context information

[Matthias Clasen <matthiasc src gnome org>]

commit b9ed027ed762f5ee384defcf4cfa5bc6c9279968
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Nov 21 23:19:27 2021 -0500

    Allow serializing context information
    
    Optionally include context information in the
    serialization and restore it. This will be useful
    for transporting for giving tests complete data
    that affects their output.
    
    Some tests included.

 pango/pango-layout.h  |   5 ++
 pango/serializer.c    | 139 ++++++++++++++++++++++++++++++++++++++++++++++----
 tests/testserialize.c |  45 ++++++++++++++++
 3 files changed, 179 insertions(+), 10 deletions(-)
---
diff --git a/pango/pango-layout.h b/pango/pango-layout.h
index e9b4710c..3c43c202 100644
--- a/pango/pango-layout.h
+++ b/pango/pango-layout.h
@@ -354,6 +354,7 @@ GSList *         pango_layout_get_lines_readonly   (PangoLayout    *layout);
 /**
  * PangoLayoutSerializeFlags:
  * @PANGO_LAYOUT_SERIALIZE_DEFAULT: Default behavior
+ * @PANGO_LAYOUT_SERIALIZE_CONTEXT: Include context information
  *
  * Flags that influence the behavior of [method@Pango.Layout.serialize].
  *
@@ -361,6 +362,7 @@ GSList *         pango_layout_get_lines_readonly   (PangoLayout    *layout);
  */
 typedef enum {
   PANGO_LAYOUT_SERIALIZE_DEFAULT = 0,
+  PANGO_LAYOUT_SERIALIZE_CONTEXT = 1 << 0,
 } PangoLayoutSerializeFlags;
 
 PANGO_AVAILABLE_IN_1_50
@@ -402,6 +404,8 @@ GQuark          pango_layout_deserialize_error_quark (void);
 /**
  * PangoLayoutDeserializeFlags:
  * @PANGO_LAYOUT_DESERIALIZE_DEFAULT: Default behavior
+ * @PANGO_LAYOUT_DESERIALIZE_CONTEXT: Apply context information
+ *   from the serialization to the `PangoContext`
  *
  * Flags that influence the behavior of [method@Pango.Layout.deserialize].
  *
@@ -409,6 +413,7 @@ GQuark          pango_layout_deserialize_error_quark (void);
  */
 typedef enum {
   PANGO_LAYOUT_DESERIALIZE_DEFAULT = 0,
+  PANGO_LAYOUT_DESERIALIZE_CONTEXT = 1 << 0,
 } PangoLayoutDeserializeFlags;
 
 PANGO_AVAILABLE_IN_1_50
diff --git a/pango/serializer.c b/pango/serializer.c
index b9c24422..ca92eb21 100644
--- a/pango/serializer.c
+++ b/pango/serializer.c
@@ -23,6 +23,7 @@
 
 #include <pango/pango-layout.h>
 #include <pango/pango-layout-private.h>
+#include <pango/pango-context-private.h>
 #include <pango/pango-enum-types.h>
 
 #include <json-glib/json-glib.h>
@@ -211,8 +212,43 @@ add_tab_array (JsonBuilder   *builder,
   json_builder_end_object (builder);
 }
 
+static void
+add_context (JsonBuilder  *builder,
+             PangoContext *context)
+{
+  json_builder_begin_object (builder);
+
+  /* Note: since we don't create the context when deserializing,
+   * we don't strip out default values here to ensure that the
+   * context gets updated as expected.
+   */
+
+  if (context->set_language)
+    {
+      json_builder_set_member_name (builder, "language");
+      json_builder_add_string_value (builder, pango_language_to_string (context->set_language));
+    }
+
+  json_builder_set_member_name (builder, "base-gravity");
+  add_enum_value (builder, PANGO_TYPE_GRAVITY, context->base_gravity, FALSE);
+
+  json_builder_set_member_name (builder, "gravity-hint");
+  add_enum_value (builder, PANGO_TYPE_GRAVITY_HINT, context->gravity_hint, FALSE);
+
+  json_builder_set_member_name (builder, "direction");
+  add_enum_value (builder, PANGO_TYPE_DIRECTION, context->base_dir, FALSE);
+
+  json_builder_set_member_name (builder, "round-glyph-positions");
+  json_builder_add_boolean_value (builder, context->round_glyph_positions);
+
+  /* FIXME transform */
+
+  json_builder_end_object (builder);
+}
+
 static JsonNode *
-layout_to_json (PangoLayout *layout)
+layout_to_json (PangoLayout               *layout,
+                PangoLayoutSerializeFlags  flags)
 {
   JsonBuilder *builder;
   JsonNode *root;
@@ -221,6 +257,12 @@ layout_to_json (PangoLayout *layout)
 
   json_builder_begin_object (builder);
 
+  if (flags & PANGO_LAYOUT_SERIALIZE_CONTEXT)
+    {
+      json_builder_set_member_name (builder, "context");
+      add_context (builder, layout->context);
+    }
+
   json_builder_set_member_name (builder, "text");
   json_builder_add_string_value (builder, layout->text);
 
@@ -663,16 +705,79 @@ fail:
   return NULL;
 }
 
+static gboolean
+apply_json_to_context (JsonReader    *reader,
+                       PangoContext  *context,
+                       GError       **error)
+{
+  if (json_reader_read_member (reader, "language"))
+    {
+      const char *value;
+      PangoLanguage *language;
+
+      value = json_reader_get_string_value (reader);
+      language = pango_language_from_string (value);
+      pango_context_set_language (context, language);
+    }
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "base-gravity"))
+    {
+      PangoGravity gravity = get_enum_value (PANGO_TYPE_GRAVITY,
+                                             json_reader_get_string_value (reader),
+                                             FALSE,
+                                             error);
+      if (gravity == -1)
+        return FALSE;
+
+      pango_context_set_base_gravity (context, gravity);
+    }
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "gravity-hint"))
+    {
+      PangoGravityHint gravity_hint = get_enum_value (PANGO_TYPE_GRAVITY_HINT,
+                                                      json_reader_get_string_value (reader),
+                                                      FALSE,
+                                                      error);
+      if (gravity_hint == -1)
+        return FALSE;
+
+      pango_context_set_gravity_hint (context, gravity_hint);
+    }
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "base-dir"))
+    {
+      PangoDirection direction = get_enum_value (PANGO_TYPE_DIRECTION,
+                                                 json_reader_get_string_value (reader),
+                                                 FALSE,
+                                                 error);
+      if (direction == -1)
+        return FALSE;
+
+      pango_context_set_base_dir (context, direction);
+    }
+  json_reader_end_member (reader);
+
+  if (json_reader_read_member (reader, "round-glyph-positions"))
+    {
+      pango_context_set_round_glyph_positions (context, json_reader_get_boolean_value (reader));
+    }
+  json_reader_end_member (reader);
+
+  return TRUE;
+}
+
 static PangoLayout *
-json_to_layout (PangoContext *context,
-                JsonNode     *node,
-                GError      **error)
+json_to_layout (PangoContext                 *context,
+                JsonNode                     *node,
+                PangoLayoutDeserializeFlags   flags,
+                GError                      **error)
 {
   JsonReader *reader;
   PangoLayout *layout;
 
-  layout = pango_layout_new (context);
-
   reader = json_reader_new (node);
   if (!json_reader_is_object (reader))
     {
@@ -683,6 +788,18 @@ json_to_layout (PangoContext *context,
       goto fail;
     }
 
+  if (flags & PANGO_LAYOUT_DESERIALIZE_CONTEXT)
+    {
+      if (json_reader_read_member (reader, "context"))
+        {
+          if (!apply_json_to_context (reader, context, error))
+            goto fail;
+        }
+      json_reader_end_member (reader);
+    }
+
+  layout = pango_layout_new (context);
+
   if (json_reader_read_member (reader, "text"))
     pango_layout_set_text (layout, json_reader_get_string_value (reader), -1);
   json_reader_end_member (reader);
@@ -711,7 +828,8 @@ json_to_layout (PangoContext *context,
           g_set_error (error,
                        PANGO_LAYOUT_DESERIALIZE_ERROR,
                        PANGO_LAYOUT_DESERIALIZE_INVALID_VALUE,
-                       "Could not parse \"font\" value: %s",
+                       "Could not parse \"%s\" value: %s",
+                       "font",
                        json_reader_get_string_value (reader));
           goto fail;
         }
@@ -820,7 +938,8 @@ json_to_layout (PangoContext *context,
 
 fail:
   g_object_unref (reader);
-  g_object_unref (layout);
+  if (layout)
+    g_object_unref (layout);
   return NULL;
 }
 
@@ -856,7 +975,7 @@ pango_layout_serialize (PangoLayout               *layout,
 
   g_return_val_if_fail (PANGO_IS_LAYOUT (layout), NULL);
 
-  node = layout_to_json (layout);
+  node = layout_to_json (layout, flags);
 
   generator = json_generator_new ();
   json_generator_set_pretty (generator, TRUE);
@@ -952,7 +1071,7 @@ pango_layout_deserialize (PangoContext                 *context,
     }
 
   node = json_parser_get_root (parser);
-  layout = json_to_layout (context, node, error);
+  layout = json_to_layout (context, node, flags, error);
 
   g_object_unref (parser);
 
diff --git a/tests/testserialize.c b/tests/testserialize.c
index d04ec7cf..43248777 100644
--- a/tests/testserialize.c
+++ b/tests/testserialize.c
@@ -242,6 +242,42 @@ test_serialize_layout_valid (void)
   g_object_unref (context);
 }
 
+static void
+test_serialize_layout_context (void)
+{
+  const char *test =
+    "{\n"
+    "  \"text\" : \"Some fun with layouts!\",\n"
+    "  \"context\" : {\n"
+    "    \"base-gravity\" : \"east\",\n"
+    "    \"language\" : \"de-de\",\n"
+    "    \"round-glyph-positions\" : \"false\"\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 (test, -1);
+
+  layout = pango_layout_deserialize (context, bytes, PANGO_LAYOUT_DESERIALIZE_CONTEXT, &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_cmpint (pango_context_get_base_gravity (context), ==, PANGO_GRAVITY_EAST);
+  g_assert_true (pango_context_get_language (context) == pango_language_from_string ("de-de"));
+  g_assert_false (pango_context_get_round_glyph_positions (context));
+
+  g_object_unref (layout);
+  g_bytes_unref (bytes);
+  g_object_unref (context);
+}
+
 static void
 test_serialize_layout_invalid (void)
 {
@@ -285,6 +321,14 @@ test_serialize_layout_invalid (void)
       "  \"alignment\" : \"nonsense\"\n"
       "}",
       PANGO_LAYOUT_DESERIALIZE_INVALID_VALUE
+    },
+    {
+      "{\n"
+      "  \"attributes\" : {\n"
+      "    \"name\" : \"This is wrong\"\n"
+      "  }\n"
+      "}",
+      PANGO_LAYOUT_DESERIALIZE_INVALID_SYNTAX
     }
   };
 
@@ -317,6 +361,7 @@ main (int argc, char *argv[])
   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/context", test_serialize_layout_context);
   g_test_add_func ("/serialize/layout/invalid", test_serialize_layout_invalid);
 
   return g_test_run ();