[aat.feat] Rework API and implementation

Fixes https://github.com/harfbuzz/harfbuzz/pull/1346

3 files changed, 102 insertions, 99 deletions

diff --git a/src/hb-aat-layout-feat-table.hh b/src/hb-aat-layout-feat-table.hh
index 98d62869..4e63ec8e 100644
--- a/src/hb-aat-layout-feat-table.hh
+++ b/src/hb-aat-layout-feat-table.hh
@@ -39,13 +39,26 @@ namespace AAT {
 
 struct SettingName
 {
+  friend struct FeatureName;
+
   int cmp (hb_aat_layout_feature_selector_t key) const
   { return (int) key - (int) setting; }
 
-  inline hb_aat_layout_feature_selector_t get_selector () const
-  { return (hb_aat_layout_feature_selector_t) (unsigned int) setting; }
+  inline hb_aat_layout_feature_selector_t get_selector (void) const
+  { return (hb_aat_layout_feature_selector_t) (unsigned) setting; }
+
+  inline void get_info (hb_aat_layout_feature_selector_info_t *s,
+			hb_aat_layout_feature_selector_t default_selector) const
+  {
+    s->name_id = nameIndex;
+
+    s->enable = (hb_aat_layout_feature_selector_t) (unsigned int) setting;
+    s->disable = default_selector == HB_AAT_LAYOUT_FEATURE_SELECTOR_INVALID ?
+		 (hb_aat_layout_feature_selector_t) (s->enable + 1) :
+		 default_selector;
 
-  inline hb_ot_name_id_t get_name_id () const { return nameIndex; }
+    s->reserved = 0;
+  }
 
   inline bool sanitize (hb_sanitize_context_t *c) const
   {
@@ -82,29 +95,34 @@ struct FeatureName
 				 * as the default. */
   };
 
-  inline unsigned int get_selectors (const feat                       *feat,
-				     hb_aat_layout_feature_selector_t *default_selector,
-				     unsigned int                      start_offset,
-				     unsigned int                     *count,
-				     hb_aat_layout_feature_selector_t *selectors) const
+  inline unsigned int get_selector_infos (unsigned int                           start_offset,
+					  unsigned int                          *selectors_count, /* IN/OUT.  May be NULL. */
+					  hb_aat_layout_feature_selector_info_t *selectors,       /* OUT.     May be NULL. */
+					  unsigned int                          *pdefault_index,  /* OUT.     May be NULL. */
+					  const void *base) const
   {
-    const UnsizedArrayOf<SettingName>& settings_table = feat+settingTableZ;
-    unsigned int settings_count = nSettings;
-    if (count && *count)
+    hb_array_t< const SettingName> settings_table = (base+settingTableZ).as_array (nSettings);
+
+    static_assert (Index::NOT_FOUND_INDEX == HB_AAT_LAYOUT_NO_SELECTOR_INDEX, "");
+
+    hb_aat_layout_feature_selector_t default_selector = HB_AAT_LAYOUT_FEATURE_SELECTOR_INVALID;
+    unsigned int default_index = Index::NOT_FOUND_INDEX;
+    if (featureFlags & Exclusive)
     {
-      unsigned int len = MIN (settings_count - start_offset, *count);
-      for (unsigned int i = 0; i < len; i++)
-        selectors[i] = settings_table[start_offset + i].get_selector ();
-      *count = len;
+      default_index = (featureFlags & NotDefault) ? featureFlags & IndexMask : 0;
+      default_selector = settings_table[default_index].get_selector ();
     }
-    if (default_selector)
+    if (pdefault_index)
+      *pdefault_index = default_index;
+
+    if (selectors_count)
     {
-      unsigned int index = (featureFlags & NotDefault) ? featureFlags & IndexMask : 0;
-      *default_selector = ((featureFlags & Exclusive) && index < settings_count)
-			  ? settings_table[index].get_selector ()
-			  : HB_AAT_LAYOUT_FEATURE_SELECTOR_INVALID;
+      hb_array_t<const SettingName> arr = settings_table.sub_array (start_offset, selectors_count);
+      unsigned int count = arr.len;
+      for (unsigned int i = 0; i < count; i++)
+        settings_table[start_offset + i].get_info (&selectors[i], default_selector);
     }
-    return settings_count;
+    return settings_table.len;
   }
 
   inline hb_aat_layout_feature_type_t get_feature_type () const
@@ -112,12 +130,6 @@ struct FeatureName
 
   inline hb_ot_name_id_t get_feature_name_id () const { return nameIndex; }
 
-  inline hb_ot_name_id_t get_feature_selector_name_id (const feat                       *feat,
-						       hb_aat_layout_feature_selector_t  key) const
-  {
-    return (feat+settingTableZ).lsearch (nSettings, key).get_name_id ();
-  }
-
   inline bool sanitize (hb_sanitize_context_t *c, const void *base) const
   {
     TRACE_SANITIZE (this);
@@ -162,32 +174,29 @@ struct feat
     return featureNameCount;
   }
 
-  inline const FeatureName& get_feature (hb_aat_layout_feature_type_t key) const
+  inline const FeatureName& get_feature (hb_aat_layout_feature_type_t feature_type) const
   {
-    return namesZ.bsearch (featureNameCount, key);
+    return namesZ.bsearch (featureNameCount, feature_type);
   }
 
   inline hb_ot_name_id_t get_feature_name_id (hb_aat_layout_feature_type_t feature) const
   { return get_feature (feature).get_feature_name_id (); }
 
-  inline hb_ot_name_id_t get_feature_selector_name_id (hb_aat_layout_feature_type_t    feature,
-						      hb_aat_layout_feature_selector_t selector) const
-  { return get_feature (feature).get_feature_selector_name_id (this, selector); }
-
-  inline unsigned int get_selectors (hb_aat_layout_feature_type_t     key,
-				    hb_aat_layout_feature_selector_t *default_selector,
-				    unsigned int                      start_offset,
-				    unsigned int                     *count,
-				    hb_aat_layout_feature_selector_t *selectors) const
+  inline unsigned int get_selector_infos (hb_aat_layout_feature_type_t           feature_type,
+					  unsigned int                           start_offset,
+					  unsigned int                          *selectors_count, /* IN/OUT.  May be NULL. */
+					  hb_aat_layout_feature_selector_info_t *selectors,       /* OUT.     May be NULL. */
+					  unsigned int                          *default_index    /* OUT.     May be NULL. */) const
   {
-    return get_feature (key).get_selectors (this, default_selector, start_offset,
-					    count, selectors);
+    return get_feature (feature_type).get_selector_infos (start_offset, selectors_count, selectors,
+							  default_index, this);
   }
 
   inline bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
     return_trace (likely (c->check_struct (this) &&
+			  version.major == 1 &&
 			  namesZ.sanitize (c, featureNameCount, this)));
   }
 
diff --git a/src/hb-aat-layout.cc b/src/hb-aat-layout.cc
index 75545adb..727da42a 100644
--- a/src/hb-aat-layout.cc
+++ b/src/hb-aat-layout.cc
@@ -39,6 +39,16 @@
 #include "hb-aat-ltag-table.hh"
 
 
+/**
+ * SECTION:hb-aat-layout
+ * @title: hb-aat-layout
+ * @short_description: Apple Advanced Typography Layout
+ * @include: hb-aat.h
+ *
+ * Functions for querying OpenType Layout features in the font face.
+ **/
+
+
 /* Table data courtesy of Apple.  Converted from mnemonics to integers
  * when moving to this file. */
 static const hb_aat_feature_mapping_t feature_mappings[] =
@@ -303,26 +313,26 @@ _hb_aat_language_get (hb_face_t *face,
  * hb_aat_layout_get_feature_types:
  * @face: a face object
  * @start_offset: iteration's start offset
- * @count:    (inout): buffer size as input, filled size as output
- * @features: (out): features buffer
+ * @feature_count:(inout) (allow-none): buffer size as input, filled size as output
+ * @features: (out caller-allocates) (array length=feature_count): features buffer
  *
- * Return value: Number of all available features
+ * Return value: Number of all available feature types.
  *
  * Since: REPLACEME
  */
 unsigned int
 hb_aat_layout_get_feature_types (hb_face_t                    *face,
 				 unsigned int                  start_offset,
-				 unsigned int                 *count,   /* IN/OUT.  May be NULL. */
-				 hb_aat_layout_feature_type_t *features /* OUT.     May be NULL. */)
+				 unsigned int                 *feature_count, /* IN/OUT.  May be NULL. */
+				 hb_aat_layout_feature_type_t *features       /* OUT.     May be NULL. */)
 {
-  return face->table.feat->get_feature_types (start_offset, count, features);
+  return face->table.feat->get_feature_types (start_offset, feature_count, features);
 }
 
 /**
  * hb_aat_layout_feature_type_get_name_id:
  * @face: a face object
- * @feature: feature id
+ * @feature_type: feature id
  *
  * Return value: Name ID index
  *
@@ -330,55 +340,33 @@ hb_aat_layout_get_feature_types (hb_face_t                    *face,
  */
 hb_ot_name_id_t
 hb_aat_layout_feature_type_get_name_id (hb_face_t                    *face,
-					hb_aat_layout_feature_type_t  feature)
-{ return face->table.feat->get_feature_name_id (feature); }
+					hb_aat_layout_feature_type_t  feature_type)
+{ return face->table.feat->get_feature_name_id (feature_type); }
 
 /**
  * hb_aat_layout_feature_type_get_selectors:
  * @face:    a face object
- * @feature: feature id
- * @default_selector: (out): if is set, the feature is exclusive
+ * @feature_type: feature id
  * @start_offset:    iteration's start offset
- * @count:  (inout): buffer size as input, filled size as output
- * @settings: (out): settings buffer
+ * @selector_count: (inout) (allow-none): buffer size as input, filled size as output
+ * @selectors: (out caller-allocates) (array length=selector_count): settings buffer
+ * @default_index: (out) (allow-none): index of default selector if any
  *
- * Per spec:
- *   For feature types that don't have exclusive settings,
- *   there will always be a pair of values. One value turns
- *   a selector on and a second value turns the selector off.
- *   The on setting must be even and the off setting must be one
- *   greater than the corresponding on setting. The off setting
- *   is therefore always odd. As a result, only the on setting
- *   should have an entry in the setting name array.
+ * If upon return, @default_index is set to #HB_AAT_LAYOUT_NO_SELECTOR_INDEX, then
+ * the feature type is non-exclusive.  Otherwise, @default_index is the index of
+ * the selector that is selected by default.
  *
- * Return value: Number of all available features
+ * Return value: Number of all available feature selectors.
  *
  * Since: REPLACEME
  */
 unsigned int
-hb_aat_layout_feature_type_get_selectors (hb_face_t                        *face,
-					  hb_aat_layout_feature_type_t      feature,
-					  hb_aat_layout_feature_selector_t *default_selector, /* OUT.     May be NULL. */
-					  unsigned int                      start_offset,
-					  unsigned int                     *count,            /* IN/OUT.  May be NULL. */
-					  hb_aat_layout_feature_selector_t *selectors         /* OUT.     May be NULL. */)
+hb_aat_layout_feature_type_get_selector_infos (hb_face_t                             *face,
+					       hb_aat_layout_feature_type_t           feature_type,
+					       unsigned int                           start_offset,
+					       unsigned int                          *selector_count, /* IN/OUT.  May be NULL. */
+					       hb_aat_layout_feature_selector_info_t *selectors,      /* OUT.     May be NULL. */
+					       unsigned int                          *default_index   /* OUT.     May be NULL. */)
 {
-  return face->table.feat->get_selectors (feature, default_selector,
-					  start_offset, count, selectors);
+  return face->table.feat->get_selector_infos (feature_type, start_offset, selector_count, selectors, default_index);
 }
-
-/**
- * hb_aat_layout_feature_selector_get_name_id:
- * @face:     a face object
- * @feature:  feature id
- * @selector: selector value
- *
- * Return value: Name ID index
- *
- * Since: REPLACEME
- */
-hb_ot_name_id_t
-hb_aat_layout_feature_selector_get_name_id (hb_face_t                        *face,
-					    hb_aat_layout_feature_type_t      feature,
-					    hb_aat_layout_feature_selector_t  selector)
-{ return face->table.feat->get_feature_selector_name_id (feature, selector); }
diff --git a/src/hb-aat-layout.h b/src/hb-aat-layout.h
index 8bd4af27..5912e012 100644
--- a/src/hb-aat-layout.h
+++ b/src/hb-aat-layout.h
@@ -430,26 +430,32 @@ typedef enum
 HB_EXTERN unsigned int
 hb_aat_layout_get_feature_types (hb_face_t                    *face,
 				 unsigned int                  start_offset,
-				 unsigned int                 *count,   /* IN/OUT.  May be NULL. */
-				 hb_aat_layout_feature_type_t *features /* OUT.     May be NULL. */);
+				 unsigned int                 *feature_count, /* IN/OUT.  May be NULL. */
+				 hb_aat_layout_feature_type_t *features       /* OUT.     May be NULL. */);
 
 HB_EXTERN hb_ot_name_id_t
 hb_aat_layout_feature_type_get_name_id (hb_face_t                    *face,
-					hb_aat_layout_feature_type_t  feature);
+					hb_aat_layout_feature_type_t  feature_type);
 
+typedef struct hb_aat_layout_feature_selector_info_t
+{
+  hb_ot_name_id_t			name_id;
+  hb_aat_layout_feature_selector_t	enable;
+  hb_aat_layout_feature_selector_t	disable;
+  /*< private >*/
+  unsigned int				reserved;
+} hb_aat_layout_feature_selector_info_t;
+
+#define HB_AAT_LAYOUT_NO_SELECTOR_INDEX		0xFFFFu
 
 HB_EXTERN unsigned int
-hb_aat_layout_feature_type_get_selectors (hb_face_t                        *face,
-					  hb_aat_layout_feature_type_t      feature,
-					  hb_aat_layout_feature_selector_t *default_selector, /* OUT.     May be NULL. */
-					  unsigned int                      start_offset,
-					  unsigned int                     *count,            /* IN/OUT.  May be NULL. */
-					  hb_aat_layout_feature_selector_t *settings          /* OUT.     May be NULL. */);
+hb_aat_layout_feature_type_get_selector_infos (hb_face_t                             *face,
+					       hb_aat_layout_feature_type_t           feature_type,
+					       unsigned int                           start_offset,
+					       unsigned int                          *selector_count, /* IN/OUT.  May be NULL. */
+					       hb_aat_layout_feature_selector_info_t *selectors,      /* OUT.     May be NULL. */
+					       unsigned int                          *default_index   /* OUT.     May be NULL. */);
 
-HB_EXTERN hb_ot_name_id_t
-hb_aat_layout_feature_selector_get_name_id (hb_face_t                        *face,
-					    hb_aat_layout_feature_type_t      feature,
-					    hb_aat_layout_feature_selector_t  selector);
 
 HB_END_DECLS