[woff2] Reconstruct transformed `glyf' table.

Reconstruct `glyf' table if it is transformed in the uncompressed
table stream.  Also add necessary structures, macros and functions.

* include/freetype/internal/wofftypes.h (WOFF2_InfoRec,
WOFF2_SubstreamRec, WOFF2_PointRec): New structures.
(WOFF2_TableRec): s/OrigLength/dst_length/.

* src/sfnt/sfwoff2.c (READ_255USHORT, READ_BASE128): Use
`FT_SET_ERROR' to set implicit `error' variable.

(WRITE_SHORT): New macro.

(N_CONTOUR_STREAM, N_POINTS_STREAM, FLAG_STREAM, GLYPH_STREAM,
COMPOSITE_STREAM, BBOX_STREAM, INSTRUCTION_STREAM): New macros to
refer to substreams of the transformed `glyf' tables.

(Read255UShort, ReadBase128): Return errors set by `FT_READ_XXX'
macros.

(with_sign, safe_int_addition): New functions to add sign to values
based on a flag and perform safe addition respectively.

(triplet_decode): Decode variable-length (flag, xCoordinate,
yCoordinate) triplet for a simple glyph.   See

  https://www.w3.org/TR/WOFF2/#triplet_decoding

(store_points, compute_bbox, composteGlyph_size, reconstruct_glyf):
New functions.

(reconstruct_font): Call `reconstruct_glyf'.

* src/sfnt/sfwoff2.h: Add required constants.

* src/sfnt/woff2tags.h: Move out constants to `sfwoff2.h'.

1 files changed, 83 insertions, 1 deletions

diff --git a/include/freetype/internal/wofftypes.h b/include/freetype/internal/wofftypes.h
index 205e64d7d..2035a251d 100644
--- a/include/freetype/internal/wofftypes.h
+++ b/include/freetype/internal/wofftypes.h
@@ -185,6 +185,34 @@ FT_BEGIN_HEADER
   /**************************************************************************
    *
    * @struct:
+   *   WOFF2_InfoRec
+   *
+   * @description:
+   *   Metadata for WOFF2 font that may be required for reconstruction of
+   *   sfnt tables.
+   *
+   * @fields:
+   *   num_glyphs ::
+   *     Number of glyphs in the font.
+   *
+   *   num_hmetrics ::
+   *     `numberOfHMetrics' field in the `hhea' table.
+   *
+   *   x_mins ::
+   *     `xMin' values of glyph bounding box.
+   */
+  typedef struct  WOFF2_InfoRec_
+  {
+    FT_UShort  num_glyphs;
+    FT_UShort  num_hmetrics;
+    FT_Short*  x_mins;
+
+  } WOFF2_InfoRec, *WOFF2_Info;
+
+
+  /**************************************************************************
+   *
+   * @struct:
    *   WOFF2_TableRec
    *
    * @description:
@@ -199,7 +227,7 @@ FT_BEGIN_HEADER
   {
     FT_Byte   FlagByte;           /* table type and flags      */
     FT_ULong  Tag;                /* table file offset         */
-    FT_ULong  OrigLength;         /* uncompressed table length */
+    FT_ULong  dst_length;         /* uncompressed table length */
     FT_ULong  TransformLength;    /* transformed length        */
 
     FT_ULong  flags;              /* calculated flags          */
@@ -211,6 +239,60 @@ FT_BEGIN_HEADER
   } WOFF2_TableRec, *WOFF2_Table;
 
 
+  /**************************************************************************
+   *
+   * @struct:
+   *   WOFF2_SubstreamRec
+   *
+   * @description:
+   *   This structure stores information about a substream in the transformed
+   *   `glyf' table in a WOFF2 stream.
+   *
+   * @fields:
+   *   start ::
+   *     Beginning of the substream relative to uncompressed table stream.
+   *
+   *   offset ::
+   *     Offset of the substream relative to uncompressed table stream.
+   *
+   *   size ::
+   *     Size of the substream.
+   */
+  typedef struct  WOFF2_SubstreamRec_
+  {
+    FT_ULong  start;
+    FT_ULong  offset;
+    FT_ULong  size;
+  } WOFF2_SubstreamRec, *WOFF2_Substream;
+
+
+  /**************************************************************************
+   *
+   * @struct:
+   *   WOFF2_PointRec
+   *
+   * @description:
+   *   This structure stores information about a point in the transformed
+   *   `glyf' table in a WOFF2 stream.
+   *
+   * @fields:
+   *   x ::
+   *     x-coordinate.
+   *
+   *   y ::
+   *     y-coordinate.
+   *
+   *   on_curve ::
+   *     on-curve.
+   */
+  typedef struct  WOFF2_PointRec_
+  {
+    FT_Int   x;
+    FT_Int   y;
+    FT_Bool  on_curve;
+  } WOFF2_PointRec, *WOFF2_Point;
+
+
 FT_END_HEADER
 
 #endif /* WOFFTYPES_H_ */