ref: a960be9e5e9846e1e4e8d2254e0b405fbf84346b
parent: d2c3bbcd8ec175a750d76f0bf50162ea9e3aaf85
author: Ben Wagner <bungeman@chromium.org>
date: Fri Mar 18 13:41:01 EDT 2022
[woff2] Support overlap flag for simple glyphs. In the woff2 spec it has been proposed to allow the OVERLAP_SIMPLE flag to be retained through the woff2 format [0]. [0] https://www.w3.org/TR/WOFF2/#glyf_table_format * src/sfnt/sfwoff2.h (GLYF_OVERLAP_SIMPLE): add glyf flag. * src/sfnt/sfwoff2.c (reconstruct_glyf): parse optionFlags and overlapSimpleBitmap[]. (store_points): set OVERLAP_SIMPLE on first point's flag if the overlap bit is set.
--- a/src/sfnt/sfwoff2.c
+++ b/src/sfnt/sfwoff2.c
@@ -84,7 +84,9 @@
#define BBOX_STREAM 5
#define INSTRUCTION_STREAM 6
+#define HAVE_OVERLAP_SIMPLE_BITMAP 0x1
+
static void
stream_close( FT_Stream stream )
{@@ -522,6 +524,7 @@
const WOFF2_Point points,
FT_UShort n_contours,
FT_UShort instruction_len,
+ FT_Bool have_overlap,
FT_Byte* dst,
FT_ULong dst_size,
FT_ULong* glyph_size )
@@ -549,6 +552,9 @@
FT_Int dy = point.y - last_y;
+ if ( i == 0 && have_overlap )
+ flag |= GLYF_OVERLAP_SIMPLE;
+
if ( dx == 0 )
flag |= GLYF_THIS_X_IS_SAME;
else if ( dx > -256 && dx < 256 )
@@ -833,6 +839,7 @@
FT_UInt num_substreams = 7;
+ FT_UShort option_flags;
FT_UShort num_glyphs;
FT_UShort index_format;
FT_ULong expected_loca_length;
@@ -839,9 +846,11 @@
FT_UInt offset;
FT_UInt i;
FT_ULong points_size;
- FT_ULong bitmap_length;
FT_ULong glyph_buf_size;
FT_ULong bbox_bitmap_offset;
+ FT_ULong bbox_bitmap_length;
+ FT_ULong overlap_bitmap_offset = 0;
+ FT_ULong overlap_bitmap_length = 0;
const FT_ULong glyf_start = *out_offset;
FT_ULong dest_offset = *out_offset;
@@ -857,15 +866,17 @@
if ( FT_NEW_ARRAY( substreams, num_substreams ) )
goto Fail;
- if ( FT_STREAM_SKIP( 4 ) )
+ if ( FT_STREAM_SKIP( 2 ) )
goto Fail;
+ if ( FT_READ_USHORT( option_flags ) )
+ goto Fail;
if ( FT_READ_USHORT( num_glyphs ) )
goto Fail;
if ( FT_READ_USHORT( index_format ) )
goto Fail;
- FT_TRACE4(( "num_glyphs = %u; index_format = %u\n",
- num_glyphs, index_format ));
+ FT_TRACE4(( "option_flags = %u; num_glyphs = %u; index_format = %u\n",
+ option_flags, num_glyphs, index_format ));
info->num_glyphs = num_glyphs;
@@ -878,7 +889,7 @@
if ( info->loca_table->dst_length != expected_loca_length )
goto Fail;
- offset = ( 2 + num_substreams ) * 4;
+ offset = 2 + 2 + 2 + 2 + ( num_substreams * 4 );
if ( offset > info->glyf_table->TransformLength )
goto Fail;
@@ -901,6 +912,20 @@
offset += substream_size;
}
+ if ( option_flags & HAVE_OVERLAP_SIMPLE_BITMAP )
+ {+ /* Size of overlapBitmap = floor((numGlyphs + 7) / 8) */
+ overlap_bitmap_length = ( num_glyphs + 7U ) >> 3;
+ if ( overlap_bitmap_length > info->glyf_table->TransformLength - offset )
+ goto Fail;
+
+ overlap_bitmap_offset = pos + offset;
+
+ FT_TRACE5(( " Overlap bitmap: offset = %lu; size = %lu;\n",
+ overlap_bitmap_offset, overlap_bitmap_length ));
+ offset += overlap_bitmap_length;
+ }
+
if ( FT_NEW_ARRAY( loca_values, num_glyphs + 1 ) )
goto Fail;
@@ -908,8 +933,9 @@
bbox_bitmap_offset = substreams[BBOX_STREAM].offset;
/* Size of bboxBitmap = 4 * floor((numGlyphs + 31) / 32) */
- bitmap_length = ( ( num_glyphs + 31U ) >> 5 ) << 2;
- substreams[BBOX_STREAM].offset += bitmap_length;
+ bbox_bitmap_length = ( ( num_glyphs + 31U ) >> 5 ) << 2;
+ /* bboxStreamSize is the combined size of bboxBitmap and bboxStream. */
+ substreams[BBOX_STREAM].offset += bbox_bitmap_length;
glyph_buf_size = WOFF2_DEFAULT_GLYPH_BUF;
if ( FT_NEW_ARRAY( glyph_buf, glyph_buf_size ) )
@@ -1025,8 +1051,11 @@
FT_ULong flag_size;
FT_ULong triplet_size;
FT_ULong triplet_bytes_used;
- FT_Byte* flags_buf = NULL;
- FT_Byte* triplet_buf = NULL;
+ FT_Bool have_overlap = FALSE;
+ FT_Byte overlap_bitmap;
+ FT_ULong overlap_offset;
+ FT_Byte* flags_buf = NULL;
+ FT_Byte* triplet_buf = NULL;
FT_UShort instruction_size;
FT_ULong size_needed;
FT_Int end_point;
@@ -1035,6 +1064,17 @@
FT_Byte* pointer = NULL;
+ /* Set `have_overlap`. */
+ if ( overlap_bitmap_offset )
+ {+ overlap_offset = overlap_bitmap_offset + ( i >> 3 );
+ if ( FT_STREAM_SEEK( overlap_offset ) ||
+ FT_READ_BYTE( overlap_bitmap ) )
+ goto Fail;
+ if ( overlap_bitmap & ( 0x80 >> ( i & 7 ) ) )
+ have_overlap = TRUE;
+ }
+
if ( FT_NEW_ARRAY( n_points_arr, n_contours ) )
goto Fail;
@@ -1155,6 +1195,7 @@
points,
n_contours,
instruction_size,
+ have_overlap,
glyph_buf,
glyph_buf_size,
&glyph_size ) )
--- a/src/sfnt/sfwoff2.h
+++ b/src/sfnt/sfwoff2.h
@@ -56,6 +56,7 @@
#define GLYF_REPEAT 1 << 3
#define GLYF_THIS_X_IS_SAME 1 << 4
#define GLYF_THIS_Y_IS_SAME 1 << 5
+#define GLYF_OVERLAP_SIMPLE 1 << 6
/* Other constants */
#define CONTOUR_OFFSET_END_POINT 10