Part of Bug 325714 – Pango should respect $LANGUAGE

2007-05-14  Behdad Esfahbod  <behdad@gnome.org>

        Part of Bug 325714 – Pango should respect $LANGUAGE

        * pango/pango-ot.h:
        * pango/pango-ot-ruleset.c (pango_ot_ruleset_get_for),
        (pango_ot_ruleset_description_hash),
        (pango_ot_ruleset_description_equal),
        (pango_ot_ruleset_description_copy),
        (pango_ot_ruleset_description_free):
        Add new engine API:

                PangoOTRulesetDescription
                pango_ot_ruleset_get_for()
                pango_ot_ruleset_description_hash()
                pango_ot_ruleset_description_equal()
                pango_ot_ruleset_description_copy()
                pango_ot_ruleset_description_free()

        The main addition is pango_ot_ruleset_get_for() that
        takes a ruleset description, ie. script/language and list
        of GSUB/GPOS features to apply, and returns a ruleset.
        It manages all the work to cache rulesets, so modules
        don't have to do that anymore.  Given that modules do not
        deal with just one ruleset anymore (because we want to
        respect language, and allow user-selected features), this
        makes their life way easier.

        * docs/pango-sections.txt:
        * docs/tmpl/opentype.sgml:
        Update.


svn path=/trunk/; revision=2290

1 files changed, 236 insertions, 10 deletions

diff --git a/pango/pango-ot-ruleset.c b/pango/pango-ot-ruleset.c
index 8efdcff9..7296fa90 100644
--- a/pango/pango-ot-ruleset.c
+++ b/pango/pango-ot-ruleset.c
@@ -95,6 +95,83 @@ pango_ot_ruleset_finalize (GObject *object)
 }
 
 /**
+ * pango_ot_ruleset_get_for:
+ * @info: a #PangoOTInfo.
+ * @desc: a #PangoOTRulesetDescription.
+ *
+ * Returns a ruleset for the given OpenType info and ruleset
+ * description.  The returned ruleset should not be modified.
+ *
+ * The static feature map members of @desc should be alive as
+ * long as @info is.
+ *
+ * Return value: the #PangoOTRuleset for @desc. This object will have
+ * the same lifetime as @info.
+ *
+ * Since: 1.18
+ **/
+const PangoOTRuleset *
+pango_ot_ruleset_get_for (PangoOTInfo                     *info,
+			  const PangoOTRulesetDescription *desc)
+{
+  PangoOTRuleset *ruleset;
+  static GQuark rulesets_quark = 0;
+  GHashTable *rulesets;
+
+  g_return_val_if_fail (info != NULL, NULL);
+  g_return_val_if_fail (desc != NULL, NULL);
+
+  if (!rulesets_quark)
+    rulesets_quark = g_quark_from_string ("pango-info-rulesets");
+
+  rulesets = g_object_get_qdata (G_OBJECT (info), rulesets_quark);
+
+  if (!rulesets)
+    {
+      rulesets = g_hash_table_new_full ((GHashFunc)  pango_ot_ruleset_description_hash,
+					(GEqualFunc) pango_ot_ruleset_description_equal,
+					(GDestroyNotify) pango_ot_ruleset_description_free,
+					(GDestroyNotify) g_object_unref);
+
+      g_object_set_qdata_full (G_OBJECT (info), rulesets_quark, rulesets, (GDestroyNotify) g_hash_table_destroy);
+    }
+
+  ruleset = g_hash_table_lookup (rulesets, desc);
+
+  if (!ruleset)
+    {
+      ruleset = pango_ot_ruleset_new_for (info,
+					  desc->script,
+					  desc->language);
+
+      if (desc->n_static_gsub_features)
+	pango_ot_ruleset_maybe_add_features (ruleset, PANGO_OT_TABLE_GSUB,
+					     desc->static_gsub_features,
+					     desc->n_static_gsub_features);
+      if (desc->n_static_gpos_features)
+	pango_ot_ruleset_maybe_add_features (ruleset, PANGO_OT_TABLE_GPOS,
+					     desc->static_gpos_features,
+					     desc->n_static_gpos_features);
+
+      if (desc->n_other_features)
+        {
+	  pango_ot_ruleset_maybe_add_features (ruleset, PANGO_OT_TABLE_GSUB,
+					       desc->other_features,
+					       desc->n_other_features);
+	  pango_ot_ruleset_maybe_add_features (ruleset, PANGO_OT_TABLE_GPOS,
+					       desc->other_features,
+					       desc->n_other_features);
+	}
+
+      g_hash_table_insert (rulesets,
+			   pango_ot_ruleset_description_copy (desc),
+			   ruleset);
+    }
+
+  return ruleset;
+}
+
+/**
  * pango_ot_ruleset_new:
  * @info: a #PangoOTInfo.
  *
@@ -108,7 +185,7 @@ pango_ot_ruleset_new (PangoOTInfo *info)
 {
   PangoOTRuleset *ruleset;
 
-  g_return_val_if_fail (info != NULL, NULL);
+  g_return_val_if_fail (PANGO_IS_OT_INFO (info), NULL);
 
   ruleset = g_object_new (PANGO_TYPE_OT_RULESET, NULL);
 
@@ -178,10 +255,14 @@ pango_ot_ruleset_new_for (PangoOTInfo       *info,
 			  PangoScript        script,
 			  PangoLanguage     *language)
 {
-  PangoOTRuleset *ruleset = pango_ot_ruleset_new (info);
+  PangoOTRuleset *ruleset;
   PangoOTTag script_tag, language_tag;
   PangoOTTableType table_type;
 
+  g_return_val_if_fail (PANGO_IS_OT_INFO (info), NULL);
+
+  ruleset = pango_ot_ruleset_new (info);
+
   script_tag   = pango_ot_tag_from_script (script);
   language_tag = pango_ot_tag_from_language (language);
 
@@ -226,7 +307,7 @@ pango_ot_ruleset_add_feature (PangoOTRuleset   *ruleset,
   PangoOTRule tmp_rule;
 
   g_return_if_fail (PANGO_IS_OT_RULESET (ruleset));
-  g_return_if_fail (PANGO_IS_OT_INFO (ruleset->info));
+  g_return_if_fail (ruleset->info != NULL);
 
   if (feature_index == PANGO_OT_NO_FEATURE)
     return;
@@ -269,7 +350,7 @@ pango_ot_ruleset_maybe_add_feature (PangoOTRuleset          *ruleset,
   guint feature_index;
 
   g_return_val_if_fail (PANGO_IS_OT_RULESET (ruleset), FALSE);
-  g_return_val_if_fail (PANGO_IS_OT_INFO (ruleset->info), FALSE);
+  g_return_val_if_fail (ruleset->info != NULL, FALSE);
 
   pango_ot_info_find_feature (ruleset->info, table_type,
 			      feature_tag,
@@ -304,16 +385,16 @@ pango_ot_ruleset_maybe_add_feature (PangoOTRuleset          *ruleset,
  *
  * Since: 1.18
  **/
-int
+guint
 pango_ot_ruleset_maybe_add_features (PangoOTRuleset          *ruleset,
 				     PangoOTTableType         table_type,
 				     const PangoOTFeatureMap *features,
-				     int                      n_features)
+				     guint                    n_features)
 {
-  int i, n_found_features = 0;
+  guint i, n_found_features = 0;
 
   g_return_val_if_fail (PANGO_IS_OT_RULESET (ruleset), 0);
-  g_return_val_if_fail (PANGO_IS_OT_INFO (ruleset->info), 0);
+  g_return_val_if_fail (ruleset->info != NULL, 0);
 
   for (i = 0; i < n_features; i++)
     {
@@ -350,7 +431,7 @@ pango_ot_ruleset_substitute  (const PangoOTRuleset *ruleset,
   HB_GSUB gsub = NULL;
 
   g_return_if_fail (PANGO_IS_OT_RULESET (ruleset));
-  g_return_if_fail (PANGO_IS_OT_INFO (ruleset->info));
+  g_return_if_fail (ruleset->info != NULL);
 
   for (i = 0; i < ruleset->rules->len; i++)
     {
@@ -394,7 +475,7 @@ pango_ot_ruleset_position (const PangoOTRuleset *ruleset,
   HB_GPOS gpos = NULL;
 
   g_return_if_fail (PANGO_IS_OT_RULESET (ruleset));
-  g_return_if_fail (PANGO_IS_OT_INFO (ruleset->info));
+  g_return_if_fail (ruleset->info != NULL);
 
   for (i = 0; i < ruleset->rules->len; i++)
     {
@@ -422,3 +503,148 @@ pango_ot_ruleset_position (const PangoOTRuleset *ruleset,
     buffer->applied_gpos = TRUE;
 }
 
+/* ruleset descriptions */
+
+/**
+ * pango_ot_ruleset_description_hash:
+ * @desc: a ruleset description
+ *
+ * Computes a hash of a #PangoOTRulesetDescription structure suitable
+ * to be used, for example, as an argument to g_hash_table_new().
+ *
+ * Return value: the hash value.
+ *
+ * Since: 1.18
+ **/
+guint
+pango_ot_ruleset_description_hash  (const PangoOTRulesetDescription *desc)
+{
+  guint hash = 0;
+  guint i;
+
+  hash ^= desc->script;
+  hash ^= GPOINTER_TO_UINT (desc->language);
+
+  hash ^= desc->n_static_gsub_features << 8;
+  hash ^= GPOINTER_TO_UINT (desc->static_gsub_features);
+
+  hash ^= desc->n_static_gpos_features << 12;
+  hash ^= GPOINTER_TO_UINT (desc->static_gpos_features);
+
+  hash ^= desc->n_other_features << 16;
+  for (i = 0; i < desc->n_other_features; i++)
+    {
+      hash ^= * (guint32 *) desc->other_features[i].feature_name;
+      hash ^= desc->other_features[i].property_bit;
+    }
+
+  return hash;
+}
+
+/**
+ * pango_ot_ruleset_description_equal:
+ * @desc1: a ruleset description
+ * @desc2: a ruleset description
+ *
+ * Compares two ruleset descriptions for equality.
+ * Two ruleset descriptions are considered equal if the rulesets
+ * they describe are provably identical.  This means that their
+ * script, language, and all feature sets should be equal.  For static feature
+ * sets, the array addresses are compared directly, while for other
+ * features, the list of features is compared one by one.
+ * (Two ruleset descriptions may result in identical rulesets
+ * being created, but still compare %FALSE.)
+ *
+ * Return value: %TRUE if two ruleset descriptions are identical,
+ *               %FALSE otherwise.
+ *
+ * Since: 1.18
+ **/
+gboolean
+pango_ot_ruleset_description_equal (const PangoOTRulesetDescription *desc1,
+				    const PangoOTRulesetDescription *desc2)
+{
+  guint i;
+
+#undef CHECK
+#define CHECK(x) if (desc1->x != desc2->x) return FALSE;
+#define CHECK_FEATURE_NAME(x) if (*(guint32 *)desc1->x != *(guint32 *)desc2->x) return FALSE
+
+  CHECK (script);
+  CHECK (language);
+
+  CHECK (static_gsub_features);
+  CHECK (n_static_gsub_features);
+  CHECK (static_gpos_features);
+  CHECK (n_static_gpos_features);
+
+  CHECK (n_other_features);
+
+  for (i = 0; i < desc1->n_other_features; i++)
+    {
+      CHECK_FEATURE_NAME (other_features[i].feature_name);
+      CHECK (other_features[i].property_bit);
+    }
+
+#undef CHECK
+
+  return TRUE;
+}
+
+/**
+ * pango_ot_ruleset_description_copy:
+ * @desc: ruleset description to copy
+ *
+ * Creates a copy of @desc, which should be freed with
+ * pango_ot_ruleset_description_free(). Primarily used internally
+ * by pango_ot_ruleset_get_for() to cache rulesets for ruleset
+ * descriptions.
+ *
+ * Return value: the newly allocated #PangoOTRulesetDescription, which
+ *               should be freed with pango_ot_ruleset_description_free().
+ *
+ * Since: 1.18
+ **/
+PangoOTRulesetDescription *
+pango_ot_ruleset_description_copy  (const PangoOTRulesetDescription *desc)
+{
+  PangoOTRulesetDescription *copy;
+
+  g_return_val_if_fail (desc != NULL, NULL);
+
+  copy = g_slice_new (PangoOTRulesetDescription);
+
+  *copy = *desc;
+
+  if (desc->n_other_features)
+    {
+      PangoOTFeatureMap *map = g_new (PangoOTFeatureMap, desc->n_other_features);
+      memcpy (map, desc->other_features, desc->n_other_features * sizeof (PangoOTFeatureMap));
+      copy->other_features = map;
+    }
+  else
+    {
+      copy->other_features = NULL;
+    }
+
+  return copy;
+}
+
+/**
+ * pango_ot_ruleset_description_free:
+ * @desc: an allocated #PangoOTRulesetDescription
+ *
+ * Frees a ruleset description allocated by 
+ * pango_ot_ruleset_description_copy().
+ *
+ * Since: 1.18
+ **/
+void
+pango_ot_ruleset_description_free  (PangoOTRulesetDescription *desc)
+{
+  g_return_if_fail (desc != NULL);
+
+  free ((gpointer) desc->other_features);
+
+  g_slice_free (PangoOTRulesetDescription, desc);
+}