Add pango_attr_list_to/from_string

Add an api to serialize PangoAttrList.

This will be useful in testing and debugging.

pango/pango-attributes.c

@@ -2524,6 +2524,549 @@ pango_attr_list_filter (PangoAttrList       *list,
   return new;
 }
 
+/* {{{ PangoAttrList serialization */
+
+/* We serialize attribute lists to strings. The format
+ * is a comma-separated list of the attributes in the order
+ * in which they are in the list, with each attribute having
+ * this format:
+ *
+ * START END NICK VALUE
+ *
+ * Values that can contain a comma, such as font descriptions
+ * are quoted with "".
+ */
+
+static const char *
+get_attr_type_nick (PangoAttrType attr_type)
+{
+  GEnumClass *enum_class;
+  GEnumValue *enum_value;
+
+  enum_class = g_type_class_ref (pango_attr_type_get_type ());
+  enum_value = g_enum_get_value (enum_class, attr_type);
+  g_type_class_unref (enum_class);
+
+  return enum_value->value_nick;
+}
+
+static GType
+get_attr_value_type (PangoAttrType type)
+{
+  switch ((int)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
+append_enum_value (GString *str,
+                   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);
+  g_type_class_unref (enum_class);
+
+  if (enum_value)
+    g_string_append_printf (str, " %s", enum_value->value_nick);
+  else
+    g_string_append_printf (str, " %d", value);
+}
+
+static void
+attr_print (GString        *str,
+            PangoAttribute *attr)
+{
+  PangoAttrString *string;
+  PangoAttrLanguage *lang;
+  PangoAttrInt *integer;
+  PangoAttrFloat *flt;
+  PangoAttrFontDesc *font;
+  PangoAttrColor *color;
+  PangoAttrShape *shape;
+  PangoAttrSize *size;
+  PangoAttrFontFeatures *features;
+
+  g_string_append_printf (str, "%u %u ", attr->start_index, attr->end_index);
+
+  g_string_append (str, get_attr_type_nick (attr->klass->type));
+
+  if (attr->klass->type == PANGO_ATTR_WEIGHT ||
+      attr->klass->type == PANGO_ATTR_STYLE ||
+      attr->klass->type == PANGO_ATTR_STRETCH ||
+      attr->klass->type == PANGO_ATTR_VARIANT ||
+      attr->klass->type == PANGO_ATTR_GRAVITY ||
+      attr->klass->type == PANGO_ATTR_GRAVITY_HINT ||
+      attr->klass->type == PANGO_ATTR_UNDERLINE ||
+      attr->klass->type == PANGO_ATTR_OVERLINE ||
+      attr->klass->type == PANGO_ATTR_BASELINE_SHIFT ||
+      attr->klass->type == PANGO_ATTR_FONT_SCALE ||
+      attr->klass->type == PANGO_ATTR_TEXT_TRANSFORM)
+    append_enum_value (str, get_attr_value_type (attr->klass->type), ((PangoAttrInt *)attr)->value);
+  else if (attr->klass->type == PANGO_ATTR_STRIKETHROUGH ||
+           attr->klass->type == PANGO_ATTR_ALLOW_BREAKS ||
+           attr->klass->type == PANGO_ATTR_INSERT_HYPHENS ||
+           attr->klass->type == PANGO_ATTR_FALLBACK)
+    g_string_append (str, ((PangoAttrInt *)attr)->value ? " true" : " false");
+  else if ((string = pango_attribute_as_string (attr)) != NULL)
+    g_string_append_printf (str, " %s", string->value);
+  else if ((lang = pango_attribute_as_language (attr)) != NULL)
+    g_string_append_printf (str, " %s", pango_language_to_string (lang->value));
+  else if ((integer = pango_attribute_as_int (attr)) != NULL)
+    g_string_append_printf (str, " %d", integer->value);
+  else if ((flt = pango_attribute_as_float (attr)) != NULL)
+    {
+      char buf[20];
+      g_ascii_formatd (buf, 20, " %f", flt->value);
+      g_string_append_printf (str, " %s", buf);
+    }
+  else if ((font = pango_attribute_as_font_desc (attr)) != NULL)
+    {
+      char *s = pango_font_description_to_string (font->desc);
+      g_string_append_printf (str, " \"%s\"", s);
+      g_free (s);
+    }
+  else if ((color = pango_attribute_as_color (attr)) != NULL)
+    {
+      char *s = pango_color_to_string (&color->color);
+      g_string_append_printf (str, " %s", s);
+      g_free (s);
+    }
+  else if ((shape = pango_attribute_as_shape (attr)) != NULL)
+    g_string_append (str, "shape"); /* FIXME */
+  else if ((size = pango_attribute_as_size (attr)) != NULL)
+    g_string_append_printf (str, " %d", size->size);
+  else if ((features = pango_attribute_as_font_features (attr)) != NULL)
+    g_string_append_printf (str, " \"%s\"", features->features);
+  else
+    g_assert_not_reached ();
+}
+
+/**
+ * pango_attr_list_to_string:
+ * @list: a `PangoAttrList`
+ *
+ * Serializes a `PangoAttrList` to a string.
+ *
+ * No guarantees are made about the format of the string,
+ * it may change between Pango versions.
+ *
+ * The intended use of this function is testing and
+ * debugging. The format is not meant as a permanent
+ * storage format.
+ *
+ * Returns: (transfer full): a newly allocated string
+ * Since: 1.50
+ */
+char *
+pango_attr_list_to_string (PangoAttrList *list)
+{
+  GString *s;
+
+  s = g_string_new ("");
+
+  if (list->attributes)
+    for (int i = 0; i < list->attributes->len; i++)
+      {
+        PangoAttribute *attr = g_ptr_array_index (list->attributes, i);
+
+        if (i > 0)
+          g_string_append (s, "\n");
+        attr_print (s, attr);
+      }
+
+  return g_string_free (s, FALSE);
+}
+
+static PangoAttrType
+get_attr_type_by_nick (const char *nick,
+                       int         len)
+{
+  GEnumClass *enum_class;
+
+  enum_class = g_type_class_ref (pango_attr_type_get_type ());
+  for (GEnumValue *ev = enum_class->values; ev->value_name; ev++)
+    {
+      if (ev->value_nick && strncmp (ev->value_nick, nick, len) == 0)
+        {
+          g_type_class_unref (enum_class);
+          return (PangoAttrType) ev->value;
+        }
+    }
+
+  g_type_class_unref (enum_class);
+  return PANGO_ATTR_INVALID;
+}
+
+static int
+get_attr_value (PangoAttrType  type,
+                const char    *str,
+                int            len)
+{
+  GEnumClass *enum_class;
+  char *endp;
+  int value;
+
+  enum_class = g_type_class_ref (get_attr_value_type (type));
+  for (GEnumValue *ev = enum_class->values; ev->value_name; ev++)
+    {
+      if (ev->value_nick && strncmp (ev->value_nick, str, len) == 0)
+        {
+          g_type_class_unref (enum_class);
+          return ev->value;
+        }
+    }
+  g_type_class_unref (enum_class);
+
+  value = g_ascii_strtoll (str, &endp, 10);
+  if (endp - str == len)
+    return value;
+
+  return -1;
+}
+
+static gboolean
+is_valid_end_char (char c)
+{
+  return c == ',' || c == '\n' || c == '\0';
+}
+
+/**
+ * pango_attr_list_from_string:
+ * @text: a string
+ *
+ * Deserializes a `PangoAttrList` from a string.
+ *
+ * This is the counterpart to [func@Pango.AttrList.to_string].
+ * See that functions for details about the format.
+ *
+ * Returns: (transfer full) (nullable): a new `PangoAttrList`
+ * Since: 1.50
+ */
+PangoAttrList *
+pango_attr_list_from_string (const char *text)
+{
+  PangoAttrList *list;
+  const char *p;
+
+  g_return_val_if_fail (text != NULL, NULL);
+
+  list = pango_attr_list_new ();
+
+  if (*text == '\0')
+    return list;
+
+  list->attributes = g_ptr_array_new ();
+
+  p = text + strspn (text, " \t\n");
+  while (*p)
+    {
+      char *endp;
+      gint64 start_index;
+      gint64 end_index;
+      char *str;
+      PangoAttrType attr_type;
+      PangoAttribute *attr;
+      PangoLanguage *lang;
+      gint64 integer;
+      PangoFontDescription *desc;
+      PangoColor color;
+      double num;
+
+      start_index = g_ascii_strtoll (p, &endp, 10);
+      if (*endp != ' ')
+        goto fail;
+
+      p = endp + strspn (endp, " ");
+      if (!*p)
+        goto fail;
+
+      end_index = g_ascii_strtoll (p, &endp, 10);
+      if (*endp != ' ')
+        goto fail;
+
+      p = endp + strspn (endp, " ");
+
+      endp = (char *)strpbrk (p, " ");
+      attr_type = get_attr_type_by_nick (p, endp - p);
+
+      p = endp + strspn (endp, " ");
+      if (*p == '\0')
+        goto fail;
+
+#define INT_ATTR(name,type) \
+          integer = g_ascii_strtoll (p, &endp, 10); \
+          if (!is_valid_end_char (*endp)) goto fail; \
+          attr = pango_attr_##name##_new ((type)integer);
+
+#define BOOLEAN_ATTR(name,type) \
+          if (strncmp (p, "true", strlen ("true")) == 0) \
+            { \
+              integer = 1; \
+              endp = (char *)(p + strlen ("true")); \
+            } \
+          else if (strncmp (p, "false", strlen ("false")) == 0) \
+            { \
+              integer = 0; \
+              endp = (char *)(p + strlen ("false")); \
+            } \
+          else \
+            integer = g_ascii_strtoll (p, &endp, 10); \
+          if (!is_valid_end_char (*endp)) goto fail; \
+          attr = pango_attr_##name##_new ((type)integer);
+
+#define ENUM_ATTR(name, type, min, max) \
+          endp = (char *)p + strcspn (p, ",\n"); \
+          integer = get_attr_value (attr_type, p, endp - p); \
+          attr = pango_attr_##name##_new ((type) CLAMP (integer, min, max));
+
+#define FLOAT_ATTR(name) \
+          num = g_ascii_strtod (p, &endp); \
+          if (!is_valid_end_char (*endp)) goto fail; \
+          attr = pango_attr_##name##_new ((float)num);
+
+#define COLOR_ATTR(name) \
+          endp = (char *)p + strcspn (p, ",\n"); \
+          if (!is_valid_end_char (*endp)) goto fail; \
+          str = g_strndup (p, endp - p); \
+          if (!pango_color_parse (&color, str)) \
+            { \
+              g_free (str); \
+              goto fail; \
+            } \
+          attr = pango_attr_##name##_new (color.red, color.green, color.blue); \
+          g_free (str);
+
+      switch (attr_type)
+        {
+        case PANGO_ATTR_INVALID:
+          pango_attr_list_unref (list);
+          return NULL;
+
+        case PANGO_ATTR_LANGUAGE:
+          endp = (char *)p + strcspn (p, ",\n");
+          if (!is_valid_end_char (*endp)) goto fail;
+          str = g_strndup (p, endp - p);
+          lang = pango_language_from_string (str);
+          attr = pango_attr_language_new (lang);
+          g_free (str);
+          break;
+
+        case PANGO_ATTR_FAMILY:
+          endp = (char *)p + strcspn (p, ",\n");
+          if (!is_valid_end_char (*endp)) goto fail;
+          str = g_strndup (p, endp - p);
+          attr = pango_attr_family_new (str);
+          g_free (str);
+          break;
+
+        case PANGO_ATTR_STYLE:
+          ENUM_ATTR(style, PangoStyle, PANGO_STYLE_NORMAL, PANGO_STYLE_ITALIC);
+          break;
+
+        case PANGO_ATTR_WEIGHT:
+          ENUM_ATTR(weight, PangoWeight, PANGO_WEIGHT_THIN, PANGO_WEIGHT_ULTRAHEAVY);
+          break;
+
+        case PANGO_ATTR_VARIANT:
+          ENUM_ATTR(variant, PangoVariant, PANGO_VARIANT_NORMAL, PANGO_VARIANT_TITLE_CAPS);
+          break;
+
+        case PANGO_ATTR_STRETCH:
+          ENUM_ATTR(stretch, PangoStretch, PANGO_STRETCH_ULTRA_CONDENSED, PANGO_STRETCH_ULTRA_EXPANDED);
+          break;
+
+        case PANGO_ATTR_SIZE:
+          INT_ATTR(size, int);
+          break;
+
+        case PANGO_ATTR_FONT_DESC:
+          p++;
+          endp = strchr (p, '"');
+          if (!endp) goto fail;
+          str = g_strndup (p, endp - p);
+          desc = pango_font_description_from_string (str);
+          attr = pango_attr_font_desc_new (desc);
+          pango_font_description_free (desc);
+          g_free (str);
+          endp++;
+          if (!is_valid_end_char (*endp)) goto fail;
+          break;
+
+        case PANGO_ATTR_FOREGROUND:
+          COLOR_ATTR(foreground);
+          break;
+
+        case PANGO_ATTR_BACKGROUND:
+          COLOR_ATTR(background);
+          break;
+
+        case PANGO_ATTR_UNDERLINE:
+          ENUM_ATTR(underline, PangoUnderline, PANGO_UNDERLINE_NONE, PANGO_UNDERLINE_ERROR_LINE);
+          break;
+
+        case PANGO_ATTR_STRIKETHROUGH:
+          BOOLEAN_ATTR(strikethrough, gboolean);
+          break;
+
+        case PANGO_ATTR_RISE:
+          INT_ATTR(rise, int);
+          break;
+
+        case PANGO_ATTR_SHAPE:
+          endp = (char *)strpbrk (p, ",\n");
+          p = endp  + strspn (endp, " ");
+          continue; /* FIXME */
+
+        case PANGO_ATTR_SCALE:
+          FLOAT_ATTR(scale);
+          break;
+
+        case PANGO_ATTR_FALLBACK:
+          BOOLEAN_ATTR(fallback, gboolean);
+          break;
+
+        case PANGO_ATTR_LETTER_SPACING:
+          INT_ATTR(letter_spacing, int);
+          break;
+
+        case PANGO_ATTR_UNDERLINE_COLOR:
+          COLOR_ATTR(underline_color);
+          break;
+
+        case PANGO_ATTR_STRIKETHROUGH_COLOR:
+          COLOR_ATTR(strikethrough_color);
+          break;
+
+        case PANGO_ATTR_ABSOLUTE_SIZE:
+          integer = g_ascii_strtoll (p, &endp, 10);
+          if (!is_valid_end_char (*endp)) goto fail;
+          attr = pango_attr_size_new_absolute (integer);
+          break;
+
+        case PANGO_ATTR_GRAVITY:
+          ENUM_ATTR(gravity, PangoGravity, PANGO_GRAVITY_SOUTH, PANGO_GRAVITY_WEST);
+          break;
+
+        case PANGO_ATTR_FONT_FEATURES:
+          p++;
+          endp = strchr (p, '"');
+          if (!endp) goto fail;
+          str = g_strndup (p, endp - p);
+          attr = pango_attr_font_features_new (str);
+          g_free (str);
+          endp++;
+          if (!is_valid_end_char (*endp)) goto fail;
+          break;
+
+        case PANGO_ATTR_GRAVITY_HINT:
+          ENUM_ATTR(gravity_hint, PangoGravityHint, PANGO_GRAVITY_HINT_NATURAL, PANGO_GRAVITY_HINT_LINE);
+          break;
+
+        case PANGO_ATTR_FOREGROUND_ALPHA:
+          INT_ATTR(foreground_alpha, int);
+          break;
+
+        case PANGO_ATTR_BACKGROUND_ALPHA:
+          INT_ATTR(background_alpha, int);
+          break;
+
+        case PANGO_ATTR_ALLOW_BREAKS:
+          BOOLEAN_ATTR(allow_breaks, gboolean);
+          break;
+
+        case PANGO_ATTR_SHOW:
+          INT_ATTR(show, PangoShowFlags);
+          break;
+
+        case PANGO_ATTR_INSERT_HYPHENS:
+          BOOLEAN_ATTR(insert_hyphens, gboolean);
+          break;
+
+        case PANGO_ATTR_OVERLINE:
+          ENUM_ATTR(overline, PangoOverline, PANGO_OVERLINE_NONE, PANGO_OVERLINE_SINGLE);
+          break;
+
+        case PANGO_ATTR_OVERLINE_COLOR:
+          COLOR_ATTR(overline_color);
+          break;
+
+        case PANGO_ATTR_LINE_HEIGHT:
+          FLOAT_ATTR(line_height);
+          break;
+
+        case PANGO_ATTR_ABSOLUTE_LINE_HEIGHT:
+          integer = g_ascii_strtoll (p, &endp, 10);
+          if (!is_valid_end_char (*endp)) goto fail;
+          attr = pango_attr_line_height_new_absolute (integer);
+          break;
+
+        case PANGO_ATTR_TEXT_TRANSFORM:
+          ENUM_ATTR(text_transform, PangoTextTransform, PANGO_TEXT_TRANSFORM_NONE, PANGO_TEXT_TRANSFORM_CAPITALIZE);
+          break;
+
+        case PANGO_ATTR_WORD:
+          integer = g_ascii_strtoll (p, &endp, 10);
+          if (!is_valid_end_char (*endp)) goto fail;
+          attr = pango_attr_word_new ();
+          break;
+
+        case PANGO_ATTR_SENTENCE:
+          integer = g_ascii_strtoll (p, &endp, 10);
+          if (!is_valid_end_char (*endp)) goto fail;
+          attr = pango_attr_sentence_new ();
+          break;
+
+        case PANGO_ATTR_BASELINE_SHIFT:
+          ENUM_ATTR(baseline_shift, PangoBaselineShift, 0, G_MAXINT);
+          break;
+
+        case PANGO_ATTR_FONT_SCALE:
+          ENUM_ATTR(font_scale, PangoFontScale, PANGO_FONT_SCALE_NONE, PANGO_FONT_SCALE_SMALL_CAPS);
+          break;
+
+        default:
+          g_assert_not_reached ();
+        }
+
+      attr->start_index = (guint)start_index;
+      attr->end_index = (guint)end_index;
+      g_ptr_array_add (list->attributes, attr);
+
+      p = endp;
+      if (*p)
+        {
+          if (*p == ',')
+            p++;
+          p += strspn (p, " \n");
+        }
+    }
+
+  goto success;
+
+fail:
+  pango_attr_list_unref (list);
+  list = NULL;
+
+success:
+  return list;
+}
+
 /* }}} */
 /* {{{ Attribute Iterator */
 

pango/pango-attributes.h

@@ -707,6 +707,11 @@ PANGO_AVAILABLE_IN_1_46
 gboolean                pango_attr_list_equal           (PangoAttrList         *list,
                                                          PangoAttrList         *other_list);
 
+PANGO_AVAILABLE_IN_1_50
+char *                  pango_attr_list_to_string       (PangoAttrList         *list);
+PANGO_AVAILABLE_IN_1_50
+PangoAttrList *         pango_attr_list_from_string     (const char            *text);
+
 PANGO_AVAILABLE_IN_1_44
 GType                   pango_attr_iterator_get_type    (void) G_GNUC_CONST;
 

tests/meson.build

@@ -53,6 +53,7 @@ if cairo_dep.found()
     [ 'cxx-test', [ 'cxx-test.cpp' ], [ libpangocairo_dep, gobject_dep, harfbuzz_dep ] ],
     [ 'test-harfbuzz', [ 'test-harfbuzz.c' ], [ libpangocairo_dep, gobject_dep, harfbuzz_dep ] ],
     [ 'test-break', [ 'test-break.c', 'test-common.c', 'validate-log-attrs.c' ], [libpangocairo_dep, glib_dep, harfbuzz_dep ] ],
+    [ 'testserialize', [ 'testserialize.c' ], [ libpangocairo_dep ] ],
   ]
 
   if host_system != 'darwin'

tests/testserialize.c

+/* 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 <glib.h>
+#include <pango/pangocairo.h>
+
+static void
+test_serialize_attr_list (void)
+{
+  const char *valid[] = {
+    "5 16 style italic",
+    "0 10 foreground red, 5 15 weight bold, 0 200 font-desc \"Sans Small-Caps 10\"",
+    "0 10 foreground red\n5 15 weight bold\n0 200 font-desc \"Sans Small-Caps 10\"",
+    "  0   10   fallback  false,\n 5 15 weight semilight\n\n \n \n",
+    "0 100 font-desc \"Cantarell, Sans, Italic Ultra-Light 64\", 10 11 weight 100",
+    "0 -1 size 10",
+    "0 1 weight 700, 2 4 weight book",
+    "0 200 rise 100\n5 15 family Times\n10 11 size 10240\n11 100 fallback 0\n30 60 stretch 2\n",
+    ""
+  };
+  const char *roundtripped[] = {
+    "5 16 style italic",
+    "0 10 foreground #ffff00000000\n5 15 weight bold\n0 200 font-desc \"Sans Small-Caps 10\"",
+    "0 10 foreground #ffff00000000\n5 15 weight bold\n0 200 font-desc \"Sans Small-Caps 10\"",
+    "0 10 fallback false\n5 15 weight semilight",