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LibGfx: Use a struct for reading WOFF2 transformed GLYF table

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Sam Atkins 2023-10-22 13:36:28 +01:00 • committed by Andreas Kling
parent 8e96902c75
commit 9642a0f43a
1 changed files with 69 additions and 49 deletions
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118
Userland/Libraries/LibGfx/Font/WOFF2/Font.cpp
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@ -104,22 +104,12 @@ static ErrorOr<u32> read_uint_base_128(SeekableStream& stream)
return Error::from_string_literal("UIntBase128 type is larger than 5 bytes");
}
static u16 be_u16(u8 const* ptr)
{
return (((u16)ptr[0]) << 8) | ((u16)ptr[1]);
}
static void be_u16(u8* ptr, u16 value)
{
ptr[0] = (value >> 8) & 0xff;
ptr[1] = value & 0xff;
}
static u32 be_u32(u8 const* ptr)
{
return (((u32)ptr[0]) << 24) | (((u32)ptr[1]) << 16) | (((u32)ptr[2]) << 8) | ((u32)ptr[3]);
}
static void be_u32(u8* ptr, u32 value)
{
ptr[0] = (value >> 24) & 0xff;
@ -489,7 +479,50 @@ static ErrorOr<Vector<FontPoint>> retrieve_points_of_simple_glyph(FixedMemoryStr
return points;
}
static constexpr size_t TRANSFORMED_GLYF_TABLE_HEADER_SIZE_IN_BYTES = 36;
// https://www.w3.org/TR/WOFF2/#glyf_table_format
struct [[gnu::packed]] TransformedGlyfTable {
BigEndian<u16> reserved; // = 0x0000
BigEndian<u16> option_flags; // Bit 0: if set, indicates the presence of the overlapSimpleBitmap[] bit array.
// Bits 1-15: Reserved.
BigEndian<u16> num_glyphs; // Number of glyphs
BigEndian<u16> index_format; // Offset format for loca table, should be consistent with indexToLocFormat of the
// original head table (see [OFF] specification)
BigEndian<u32> n_contour_stream_size; // Size of nContour stream in bytes
BigEndian<u32> n_points_stream_size; // Size of nPoints stream in bytes
BigEndian<u32> flag_stream_size; // Size of flag stream in bytes
BigEndian<u32> glyph_stream_size; // Size of glyph stream in bytes (a stream of variable-length encoded values, see
// description below)
BigEndian<u32> composite_stream_size; // Size of composite stream in bytes (a stream of variable-length encoded values,
// see description below)
BigEndian<u32> bbox_stream_size; // Size of bbox data in bytes representing combined length of bboxBitmap
// (a packed bit array) and bboxStream (a stream of Int16 values)
BigEndian<u32> instruction_stream_size; // Size of instruction stream (a stream of UInt8 values)
// Other fields are variable-length, and so are not represented in this struct:
// Int16 nContourStream[] Stream of Int16 values representing number of contours for each glyph record
// 255UInt16 nPointsStream[] Stream of values representing number of outline points for each contour in glyph records
// UInt8 flagStream[] Stream of UInt8 values representing flag values for each outline point.
// Vary glyphStream[] Stream of bytes representing point coordinate values using variable length encoding
// format (defined in subclause 5.2)
// Vary compositeStream[] Stream of bytes representing component flag values and associated composite glyph data
// UInt8 bboxBitmap[] Bitmap (a numGlyphs-long bit array) indicating explicit bounding boxes
// Int16 bboxStream[] Stream of Int16 values representing glyph bounding box data
// UInt8 instructionStream[] Stream of UInt8 values representing a set of instructions for each corresponding glyph
// UInt8 overlapSimpleBitmap[] A numGlyphs-long bit array that provides values for the overlap flag [bit 6] for each
// simple glyph. (Flag values for composite glyphs are already encoded as part of the
// compositeStream[]).
};
static_assert(AssertSize<TransformedGlyfTable, 36>());
}
template<>
class AK::Traits<WOFF2::TransformedGlyfTable> : public GenericTraits<WOFF2::TransformedGlyfTable> {
public:
static constexpr bool is_trivially_serializable() { return true; }
};
namespace WOFF2 {
enum class LocaElementSize {
TwoBytes,
@ -512,31 +545,18 @@ enum SimpleGlyphFlags : u8 {
static ErrorOr<GlyfAndLocaTableBuffers> create_glyf_and_loca_tables_from_transformed_glyf_table(FixedMemoryStream& table_stream)
{
u8 header_buffer[TRANSFORMED_GLYF_TABLE_HEADER_SIZE_IN_BYTES];
TRY(table_stream.read_until_filled(header_buffer));
auto header = ReadonlyBytes { header_buffer };
auto header = TRY(table_stream.read_value<TransformedGlyfTable>());
// Skip: reserved, optionFlags
u16 num_glyphs = be_u16(header.offset(4));
u16 index_format = be_u16(header.offset(6));
auto loca_element_size = index_format == 0 ? LocaElementSize::TwoBytes : LocaElementSize::FourBytes;
u32 number_of_contours_stream_size = be_u32(header.offset(8));
u32 number_of_points_stream_size = be_u32(header.offset(12));
u32 flag_stream_size = be_u32(header.offset(16));
u32 glyph_stream_size = be_u32(header.offset(20));
u32 composite_stream_size = be_u32(header.offset(24));
u32 bounding_box_stream_size = be_u32(header.offset(28));
u32 instruction_stream_size = be_u32(header.offset(32));
auto loca_element_size = header.index_format == 0 ? LocaElementSize::TwoBytes : LocaElementSize::FourBytes;
size_t table_size = TRY(table_stream.size());
u64 total_size_of_streams = number_of_contours_stream_size;
total_size_of_streams += number_of_points_stream_size;
total_size_of_streams += flag_stream_size;
total_size_of_streams += glyph_stream_size;
total_size_of_streams += composite_stream_size;
total_size_of_streams += bounding_box_stream_size;
total_size_of_streams += instruction_stream_size;
u64 total_size_of_streams = header.n_contour_stream_size;
total_size_of_streams += header.n_points_stream_size;
total_size_of_streams += header.flag_stream_size;
total_size_of_streams += header.glyph_stream_size;
total_size_of_streams += header.composite_stream_size;
total_size_of_streams += header.bbox_stream_size;
total_size_of_streams += header.instruction_stream_size;
if (table_size < total_size_of_streams)
return Error::from_string_literal("Not enough data to read in streams of transformed glyf table");
@ -544,42 +564,42 @@ static ErrorOr<GlyfAndLocaTableBuffers> create_glyf_and_loca_tables_from_transfo
auto all_tables_buffer = TRY(ByteBuffer::create_zeroed(total_size_of_streams));
u64 all_tables_buffer_offset = 0;
auto number_of_contours_stream_buffer = TRY(table_stream.read_some(all_tables_buffer.span().slice(all_tables_buffer_offset, number_of_contours_stream_size)));
auto number_of_contours_stream_buffer = TRY(table_stream.read_some(all_tables_buffer.span().slice(all_tables_buffer_offset, header.n_contour_stream_size)));
auto number_of_contours_stream = FixedMemoryStream(number_of_contours_stream_buffer);
all_tables_buffer_offset += number_of_contours_stream_size;
all_tables_buffer_offset += header.n_contour_stream_size;
auto number_of_points_stream_buffer = TRY(table_stream.read_some(all_tables_buffer.span().slice(all_tables_buffer_offset, number_of_points_stream_size)));
auto number_of_points_stream_buffer = TRY(table_stream.read_some(all_tables_buffer.span().slice(all_tables_buffer_offset, header.n_points_stream_size)));
auto number_of_points_stream = FixedMemoryStream(number_of_points_stream_buffer);
all_tables_buffer_offset += number_of_points_stream_size;
all_tables_buffer_offset += header.n_points_stream_size;
auto flag_stream_buffer = all_tables_buffer.span().slice(all_tables_buffer_offset, flag_stream_size);
auto flag_stream_buffer = all_tables_buffer.span().slice(all_tables_buffer_offset, header.flag_stream_size);
TRY(table_stream.read_until_filled(flag_stream_buffer));
auto flag_stream = FixedMemoryStream(flag_stream_buffer);
all_tables_buffer_offset += flag_stream_size;
all_tables_buffer_offset += header.flag_stream_size;
auto glyph_stream_buffer = all_tables_buffer.span().slice(all_tables_buffer_offset, glyph_stream_size);
auto glyph_stream_buffer = all_tables_buffer.span().slice(all_tables_buffer_offset, header.glyph_stream_size);
TRY(table_stream.read_until_filled(glyph_stream_buffer));
auto glyph_stream = FixedMemoryStream(glyph_stream_buffer);
all_tables_buffer_offset += glyph_stream_size;
all_tables_buffer_offset += header.glyph_stream_size;
auto composite_stream_buffer = all_tables_buffer.span().slice(all_tables_buffer_offset, composite_stream_size);
auto composite_stream_buffer = all_tables_buffer.span().slice(all_tables_buffer_offset, header.composite_stream_size);
TRY(table_stream.read_until_filled(composite_stream_buffer));
auto composite_stream = FixedMemoryStream(composite_stream_buffer);
all_tables_buffer_offset += composite_stream_size;
all_tables_buffer_offset += header.composite_stream_size;
size_t bounding_box_bitmap_length = ((num_glyphs + 31) >> 5) << 2;
size_t bounding_box_bitmap_length = ((header.num_glyphs + 31) >> 5) << 2;
auto bounding_box_bitmap_stream_buffer = TRY(table_stream.read_some(all_tables_buffer.span().slice(all_tables_buffer_offset, bounding_box_bitmap_length)));
auto bounding_box_bitmap_memory_stream = FixedMemoryStream(bounding_box_bitmap_stream_buffer);
auto bounding_box_bitmap_bit_stream = BigEndianInputBitStream { MaybeOwned<Stream>(bounding_box_bitmap_memory_stream) };
all_tables_buffer_offset += bounding_box_bitmap_length;
if (bounding_box_stream_size < bounding_box_bitmap_length)
if (header.bbox_stream_size < bounding_box_bitmap_length)
return Error::from_string_literal("Not enough data to read bounding box stream of transformed glyf table");
auto bounding_box_stream_buffer = TRY(table_stream.read_some(all_tables_buffer.span().slice(all_tables_buffer_offset, bounding_box_stream_size - bounding_box_bitmap_length)));
auto bounding_box_stream_buffer = TRY(table_stream.read_some(all_tables_buffer.span().slice(all_tables_buffer_offset, header.bbox_stream_size - bounding_box_bitmap_length)));
auto bounding_box_stream = FixedMemoryStream(bounding_box_stream_buffer);
all_tables_buffer_offset += bounding_box_stream_size - bounding_box_bitmap_length;
all_tables_buffer_offset += header.bbox_stream_size - bounding_box_bitmap_length;
auto instruction_buffer = all_tables_buffer.span().slice(all_tables_buffer_offset, instruction_stream_size);
auto instruction_buffer = all_tables_buffer.span().slice(all_tables_buffer_offset, header.instruction_stream_size);
TRY(table_stream.read_until_filled(instruction_buffer));
auto instruction_stream = FixedMemoryStream(instruction_buffer);
@ -615,7 +635,7 @@ static ErrorOr<GlyfAndLocaTableBuffers> create_glyf_and_loca_tables_from_transfo
return {};
};
for (size_t glyph_index = 0; glyph_index < num_glyphs; ++glyph_index) {
for (size_t glyph_index = 0; glyph_index < header.num_glyphs; ++glyph_index) {
size_t starting_glyf_table_size = reconstructed_glyf_table.size();
bool has_bounding_box = TRY(bounding_box_bitmap_bit_stream.read_bit());