[avar] Implement inverse map, unmap

src/hb-ot-var-avar-table.hh

@@ -49,9 +49,10 @@ struct AxisValueMap
   }
 
   public:
-  F2DOT14	fromCoord;	/* A normalized coordinate value obtained using
-				 * default normalization. */
-  F2DOT14	toCoord;	/* The modified, normalized coordinate value. */
+  F2DOT14	coords[2];
+//   F2DOT14	fromCoord;	/* A normalized coordinate value obtained using
+// 				 * default normalization. */
+//   F2DOT14	toCoord;	/* The modified, normalized coordinate value. */
 
   public:
   DEFINE_SIZE_STATIC (4);
@@ -59,12 +60,13 @@ struct AxisValueMap
 
 struct SegmentMaps : ArrayOf<AxisValueMap>
 {
-  int map (int value) const
+  int map (int value, unsigned int from_stride = 0, unsigned int to_stide = 1) const
   {
     /* The following special-cases are not part of OpenType, which requires
      * that at least -1, 0, and +1 must be mapped. But we include these as
      * part of a better error recovery scheme. */
-
+#define fromCoord coords[from_stride]
+#define toCoord coords[to_stide]
     if (len < 2)
     {
       if (!len)
@@ -91,8 +93,12 @@ struct SegmentMaps : ArrayOf<AxisValueMap>
     return arrayZ[i-1].toCoord +
 	   ((arrayZ[i].toCoord - arrayZ[i-1].toCoord) *
 	    (value - arrayZ[i-1].fromCoord) + denom/2) / denom;
+#undef toCoord
+#undef fromCoord
   }
 
+  int unmap (int value) const { return map (value, 1, 0); }
+
   public:
   DEFINE_SIZE_ARRAY (2, *this);
 };
@@ -133,6 +139,18 @@ struct avar
     }
   }
 
+  void unmap_coords (int *coords, unsigned int coords_length) const
+  {
+    unsigned int count = hb_min (coords_length, axisCount);
+
+    const SegmentMaps *map = &firstAxisSegmentMaps;
+    for (unsigned int i = 0; i < count; i++)
+    {
+      coords[i] = map->unmap (coords[i]);
+      map = &StructAfter<SegmentMaps> (*map);
+    }
+  }
+
   protected:
   FixedVersion<>version;	/* Version of the avar table
 				 * initially set to 0x00010000u */
@@ -140,7 +158,7 @@ struct avar
   HBUINT16	axisCount;	/* The number of variation axes in the font. This
 				 * must be the same number as axisCount in the
 				 * 'fvar' table. */
-  SegmentMaps   firstAxisSegmentMaps;
+  SegmentMaps	firstAxisSegmentMaps;
 
   public:
   DEFINE_SIZE_MIN (8);